Role of electrocardiogram in detecting congenital heart disease:prevalence and diagnostic accuracy of pathognomonic features

Role of electrocardiogram in detecting congenital heart disease:prevalence and diagnostic accuracy of pathognomonic features | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Role of electrocardiogram in detecting congenital heart disease:prevalence and diagnostic accuracy of pathognomonic features Somrita Laha, Debasree Gangopadhyay, Mahua Roy, Pooja Sinha This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6106927/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 10 You are reading this latest preprint version Abstract Background and aims: Congenital heart diseases (CHD) account for a major portion of congenital anomalies. Certain electrocardiogram (ECG) features have been described as pathognomonic for some CHDs, over years. If ECG can be used as a screening tool, it would prompt detection of CHDs in resource-limited areas. However, comprehensive research on ECG's diagnostic accuracy is required before embarking on such a venture. Methods: This study, conducted in a tertiary care centre of Eastern India, aims to find out actual percentage prevalence of classical ECG features in different CHDs, and therefore, to assess diagnostic accuracy of the said ECG pointers (Fig. 1: graphical abstract). Results: Significant variation in ECG findings was noted across different CHDs; some like right axis deviation in TOF showed 100% prevalence and sensitivity, while others, like leftward P axis in sinus venosus ASD, were much less common. Many ECG features were highly specific, such as 100% specific Katz-Wachtel phenomenon in post-tricuspid shunts. Also, high diagnostic accuracy of ECG was demonstrated across several CHDs; 100% accuracy for tall monophasic R in V1 in severe PS, and high accuracy (> 95%) for PR prolongation and extreme axis deviations in AVSD and Ebstein’s anomaly. Overall, ECG parameters had high specificity and accuracy but varied in sensitivity, with combinations of specific and sensitive features proving effective for diagnosis in specific CHDs. Conclusions: A combination of specific ECG features, along with simple clinical tools can effectively screen for common CHDs, guiding early referral to cardiology service, especially in areas with limited access to advanced diagnostic tools like echocardiography. Health sciences/Diseases/Cardiovascular diseases/Congenital heart defects Health sciences/Cardiology Health sciences/Cardiology/Cardiovascular biology/Cardiovascular diseases/Congenital heart defects 12 lead ECG congenital heart disease accuracy of ECG prevalence of ECG Figures Figure 1 Figure 2 KEY MESSAGES What is already known about this research? There are isolated studies on ECG pattern of different congenital heart diseases. There is also description of individual ECG features as classic finding of certain CHDs in literature. What this study adds? To our knowledge, this is the first study that holistically approaches all common structural heart defects to investigate actual prevalence of abnormal ECG. This study has also included an extensive statistical analysis to provide sensitivity, specificity and accuracy of each and every abnormal ECG feature in diagnosis of CHD, which none of the previous studies have done. INTRODUCTION Congenital heart diseases (CHD) account for nearly one third of all major congenital anomalies. Not to forget, a huge number of these defects, if diagnosed in appropriate time, are repairable leading to improved quality of life. Diagnosis of CHD is a multistep process, comprising of history, clinical examination, chest roentgenogram (CXR), electrocardiogram (ECG), echocardiography, advanced imaging studies like computed tomography (CT) and magnetic resonance imaging (MRI), and invasive procedures like cardiac catheterization. ECG changes in congenital heart diseases are explained by multiple factors, like hemodynamic changes, ventricular preponderance, anatomy of conduction system etc. Taking in account these factors, some ECG findings are seen characteristically clustered in certain CHDs, described as ‘sine qua non’ of the related defects; for example, extreme left axis deviation in atrioventricular septal defect, or early transition of RS complex in tetralogy of Fallot (TOF). 1 By pointing out abnormalities in ECG, it is often feasible to put a finger at the possible diagnosis, or narrow down the differential diagnoses. However, before deducing an anatomical or morphological diagnosis from a strip of ECG, it is extremely important to know prevalence, sensitivity, specificity and diagnostic accuracy of the findings associated with a specific defect. Over the past decades, a handful of studies have explored the spectrum of ECG features in some of the CHDs. But, most of these studies have focussed on a single CHD or a group of CHDs with common hemodynamics. Furthermore, only a few diseases have grabbed the attention of researchers in past, and no study did include all CHDs holistically or looked into the diagnostic accuracy of ECG in structural heart disease. AIM AND OBJECTIVE The primary objective of the research was to study the pattern of ECG features in common CHDs, and to assess how commonly established ECG changes are found in these patients. We considered the ECG abnormalities that have been described as classical for each CHD in literature, while assessing pattern. Along with the prevalence thus stated, we sought out to note commonly recurring deviation from known pattern, if any found. We also extended the study population to controls with structurally normal heart, to find out if any of these pathognomonic ECG pointers were noted in them. Thereafter, our final objective was to deduce sensitivity, specificity and diagnostic accuracy of ECG patterns in associated CHDs. METHODS The research was planned as a cross-sectional, observational, descriptive study. Study period was 18 months (August 2021 to January 2023). Inclusion criteria Patients with isolated CHDs as described below were included in the study. 1. Hemodynamically significant ostium secundum atrial septal defects (OSASD) defined by presence of dilated right atrium and right ventricle 2. Sinus venosus atrial septal defects (ASD) 3. Atrioventricular septal defects (AVSD), including ostium primum ASD 4. Hemodynamically significant (moderate to large) post-tricuspid shunt lesions, ventricular septal defect (VSD) and patent ductus arteriosus (PDA), defined by left ventricle end-diastolic diameter of more than + 2 z scores 5. Significant left ventricular outflow tract obstructive (LVOTO) lesions: severe aortic stenosis (AS) (defined by a peak velocity across the aortic valve of ≥ 4.0 m/s or a mean gradient across the valve of ≥ 40 mm Hg) and significant coarctation of aorta (CoA) (defined by any of these: gradient across the defect of more than 20 mm Hg, left ventricular hypertrophy, upper limb hypertension according to age and sex) 6. Classic tetralogy of Fallot (TOF) 7. Congenitally corrected transposition of great arteries (CCTGA) 8. Severe pulmonary stenosis (PS), defined by peak gradient across valve more than 64 mm Hg 9. Ebstein’s anomaly 10. Double outlet right ventricle (DORV) 11. Tricuspid atresia 12. Single ventricle/ univentricular heart Exclusion criteria Any patient with more than one congenital heart defect among those described above, or any other complex structural heart disease were excluded from the study, as it would be difficult to apply classical ECG findings in simultaneous presence of multiple CHDs (for eg, OSASD and VSD). Shunt lesions with pulmonary vascular obstructive disease leading to reversal of shunt (Eisenmenger syndrome) were excluded from the study, because this group has varied ECG depending not only the underlying hemodynamics, but also primary defect. Patients attending the Pediatric Cardiology out-patient department (OPD) during the study period were included, taking in account presence of the inclusion and exclusion criteria as above. The patients were grouped according to the type of CHD, depending on final diagnosis by echocardiography. To avoid repeated inclusion of the same patient during follow up visit as a fresh case, only patients attending the OPD for the first time were included. The study assessed how many and which established ECG features were present in patients with specific CHDs. At the end, the prevalence of each ECG feature in each CHD group was calculated as a percentage of the total patients in that group, providing insight into how common specific ECG findings are in these conditions. The particular ECG findings taken in account for diseases, were also sought for in the control population, and prevalence of these expressed as percentage. Controls The patients attending pediatric cardiology OPD who were detected to have structurally normal heart (including those with a patent foramen ovale or bicuspid aortic valve with no aortic stenosis or aortic regurgitation) were taken as control (normal) population, to aid in our statistical analysis. Data was analysed using SPSS software, version 26.0. All continuous variables were expressed as mean ± SD (standard deviation) and qualitative variables as numbers and percentages. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy was calculated for each ECG parameter in each group of congenital heart disease. The study was carried out in accordance with relevant guidelines and regulations. Study protocol was approved by the institutional research committee and ethics committee. Written informed consent was taken from the patients (older than 7 years of age) or parents/guardians for voluntary participation in the study, after informing them about every detail pertaining to the study process, procedures and requirements in a language that they 18 understand fully. The consent was collected after providing appropriate answers with adequate details for all questions of the participants/ guardians. RESULTS A total of 473 patients and 278 controls, who gave consent to participate in the study, were included. Mean age of patients was 6.62 ± 1.36 years (range 7 days to 56 years). 55.6% and 54.7% of patients group and control group comprised of male, and the rest female. Figure 2 illustrates distribution of CHDs in our study population. Table 1 shows prevalence of different ECG features in each congenital heart disease, whereas Table 2 shows prevalence of the same abnormal ECG pointers in control population. Table 1 Prevalence of different established ECG features in congenital heart diseases, and comparison of the same with other available studies Congenital heart disease ECG feature of the CHD Prevalence percentage of the ECG feature in that particular group of CHD Prevalence percentage of specific ECG feature in CHD in previous study Any new feature noted in ECG than that described in literature Hemodynamically significant Ostium secundum ASD Absence of sinus arrhythmia 97.9% No available study Left axis deviation in 1 patient (non-syndromic) PR prolongation 45.3% No available study rSR’ in right precordial leads 74.7% 54% (Refaei et al, 2017) 2 Crochetage pattern in at least 1 inferior lead 53.7% 31.7% (Cohen et al, 2000) 3 Crochetage pattern in all inferior leads 17.9% 28.13% (Shen et al, 2018) 4 Sinus venosus ASD Leftward P axis (less than 30°) 11.1% 46% (Davia et al, 1973) 5 Atrioventricular septal defect (including ostium primum ASD) Left axis deviation 34.8% No available study Extreme left axis deviation 65.2% Counterclockwise depolarization 34.8% No available study PR prolongation 73.9% 50% (Jacobsen et al, 1976) 6 Hemodynamically significant (moderate to large) post tricuspid shunt (VSD, PDA) Sign of left atrial enlargement 41.7% No available study Sign of biatrial enlargement 13.6% No available study Sign of left ventricular volume overload 66.1% No available study Large equiphasic RS in midprecordial leads (Katz-Wachtel phenomenon) 86.4% 97.1% (Sarmila et al, 2019) 7 Left ventricular outflow tract obstruction (severe AS, significant CoA) Sign of left ventricular hypertrophy 41.2% 29.4% (Shah et al, 2014) 8 ECG strain 11.7% 20.6% (Shah et al, 2014) 8 Tetralogy of Fallot Right axis deviation 100% 96% (Roberts et al, 1972) 9 Tall monophasic R in V 1 with early transition to rS in V 2 100% No available study Congenitally corrected transposition of great arteries Absence of Q wave in left precordial leads 100% 100% (Victorica et al, 1973) 10 Presence of Q wave in right precordial leads 36.4% 100% (Victorica et al, 1973) 10 Upright T wave in all precordial leads 54.5% 80% (Victorica et al, 1973) 10 Any degree of atrioventricular block 63.6% 75% (Walker et al, 1958) 11 Complete heart block 27.3% 30% (Walker et al, 1958) 11 Severe pulmonary stenosis (intact ventricular septum) Tall peaked P wave 53.1% No available study Left axis deviation in 3 patients of Noonan syndrome Tall monophasic R/ qR in V 1 100% 80% (Bassingth-waighte et al, 1963) 12 Right axis deviation 90.6% No available study Wide QRS-T angle/ strain 9.4% No available study Doppler gradient similar to ECG estimated gradient 84.4% No available study Ebstein’s anomaly Tall P wave 28.6% 15% (Assenza et al, 2013) 13 Prolonged PR interval 100% 17% (Assenza et al, 2013) 13 Right bundle branch block 57.1% 49% (Assenza et al, 2013) 13 WPW preexcitation/ delta wave 28.6% No available study DORV with subaortic VSD, no PS Prolonged PR interval 50.0% 26% (Krongrad et al, 1972) 14 Left axis deviation 37.5% No available study Counterclockwise depolarization 50.0% No available study DORV, subaortic VSD, severe PS Prolonged PR interval 52.6% 26% (Krongrad et al, 1972) 31 Left axis deviation in 1 patient, normal QRS axis in 1 patient Vertical/ right QRS axis 89.5% No available study Counterclockwise depolarization 57.9% No available study DORV, subpulmonary VSD Prolonged PR interval 0% No available study Vertical/ right QRS axis 80.0% No available study Clockwise depolarization 80.0% No available study Tricuspid atresia Tall P wave 44.4% No available study Normal QRS axis in 2 patient, Right axis deviation in 1 patient Left axis deviation 83.3% No available study Counterclockwise depolariation 77.8% No available study Left ventricular hypertrophy 22.2% No available study Single ventricle physiology with morphologic left ventricle, non-inverted outlet chamber Left axis deviation 100.0% No available study Dominant R in V 1 and equidiphasic RS in midprecordial leads 100.0% No available study Single ventricle physiology with morphologic left ventricle, inverted outlet chamber QRS axis inferior and to right 80.0% No available study Single ventricle physiology with morphologic right ventricle Right axis deviation 75.0% No available study Tall stereotyped precordial R wave 75.0% No available study Single ventricle with increased pulmonary blood flow Left atrial/ biatrial enlargement (bifid P or tall bifid P) 50.0% No available study Single ventricle with decreased pulmonary blood flow Right atrial enlargement (tall P wave) 14.3% No available study ECG: electrocardiogram; CHD: congenital heart disease; ASD: atrial septal defect; VSD: ventricular septal defect; PDA: patent ductus arteriosus; AS: aortic stenosis; CoA: coarctation of aorta; WPW: Wolff-Parkinson-White; DORV: double outlet right ventricle; PS: pulmonary stenosis Table 2 Prevalence of ECG features known as hallmark of different congenital heart diseases, as noted in control (normal) population Established ECG features of common congenital heart diseases Prevalence in control population Absence of sinus arrhythmia 4.68% PR prolongation 1.80% rSR prime in right precordial leads 6.12% Crochetage pattern in any inferior lead 0.36% Leftward P axis 1.07% Left axis deviation 2.2% Counterclockwise depolarization 7.2% Sign of left atrial enlargement 1.1% Sign of biatrial enlargement 0.7% Sign of left ventricular volume overload 6.5% Large equiphasic RS in midprecordial leads 0% Sign of left ventricular hypertrophy 3.2% ECG strain (LV strain) 0.36% Right axis deviation 13.3% Tall monophasic R in V 1 with early transition to rS in V 2 0% Absence of Q wave in left precordial leads 35.3% Presence of Q wave in right precordial leads 0.7% Upright T wave in all precordial leads 0.4% Any degree of atrioventricular block 3.9% Complete heart block 0.7% Tall peaked P wave 0.7% Tall monophasic R/ qR in V 1 0% Wide QRS-T angle/ strain (RV strain) 0.4% Right bundle branch block 1.1% WPW preexcitation/ delta wave 0.7% Vertical/ right QRS axis 20.5% Clockwise depolarization 5.03% Dominant R in V 1 and equidiphasic RS in midprecordial leads 0% Tall stereotyped precordial R wave 0% ECG: electrocardiogram; LV: left ventricle; WPW: Wolff-Parkinson-White Table 3 here shows sensitivity, specificity and diagnostic accuracy of pathognomonic typical ECG features in detection of the related CHD. Table 3 Results of statistical analysis showing diagnostic role of ECG pointers in detecting a CHD Congenital heart disease ECG feature of the CHD Sensitivity Specificity Accuracy Large Ostium secundum ASD Absence of sinus arrhythmia 97.9% 95.3% 95.9% PR prolongation 45.3% 98.2% 84.7% rSR’ in right precordial leads 74.7% 93.9% 89.0% Crochetage pattern in at least 1 inferior lead 53.7% 99.6% 87.9% Crochetage pattern in all inferior leads 11.6% 100.0% 77.5% Sinus venosus ASD Leftward P axis (less than 30°) 11.1% 98.9% 96.2% Atrioventricular septal defect (including ostium primum ASD) Left axis deviation 34.8% 97.8% 97.0% Extreme left axis deviation 65.2% 100.0% 97.3% Counterclockwise depolarization 34.8% 92.8% 88.4% PR prolongation 73.9% 98.2% 96.4% Large Post tricuspid shunt (VSD, PDA) Sign of left atrial enlargement 41.8% 98.9% 83.5% Sign of biatrial enlargement 13.6% 99.3% 76.1% Sign of left ventricular volume overload (Q in V5/V6) 66.1% 93.5% 86.1% Large equiphasic RS in midprecordial leads (Katz-Wachtel phenomenon) 86.4% 100.0% 96.3% Left ventricular outflow tract obstruction (severe AS, significant CoA) Sign of left ventricular hypertrophy 41.18% 96.76% 93.56% ECG strain 11.76% 99.64% 94.58% Tetralogy of Fallot Right axis deviation 100.00% 86.69% 90.31% Tall monophasic R in V 1 with early transition to rS in V 2 100.00% 100.00% 100.00% Congenitally corrected transposition of great arteries Absence of Q wave in left precordial leads 100.00% 64.75% 66.09% Presence of Q wave in right precordial leads 36.36% 99.28% 96.89% Upright T wave in all precordial leads 54.55% 99.64% 97.92% Any degree of atrioventricular block 63.64% 97.12% 95.85% Complete heart block 27.27% 99.28% 96.54% Severe pulmonary stenosis (intact ventricular septum) Tall peaked P wave 53.12% 99.28% 94.52% Tall monophasic R/ qR in V 1 100.00% 100.00% 100.00% Right axis deviation 90.62% 91.37% 91.29% Wide QRS-T angle/ strain 9.38% 99.64% 90.32% Ebstein’s anomaly Tall P wave 28.57% 99.28% 97.54% Prolonged PR interval 100.00% 98.20% 98.25% Right bundle branch block 57.14% 98.92% 97.89% WPW preexcitation/ delta wave 28.57% 99.28% 97.54% DORV with subaortic VSD, no PS Prolonged PR interval 50.00% 98.20% 96.85% Left axis deviation 37.50% 97.84% 96.15% Counterclockwise depolarization 50.00% 92.81% 91.61% DORV, subaortic VSD, severe PS Prolonged PR interval 52.63% 98.20% 95.29% Vertical/ right QRS axis 89.47% 79.50% 80.13% Counterclockwise depolarization 57.89% 92.81% 90.57% DORV, subpulmonary VSD Prolonged PR interval 0.00% 98.20% 96.47% Vertical/ right QRS axis 80.00% 79.50% 79.51% Clockwise depolarization 80.00% 94.96% 94.70% Tricuspid atresia Tall P wave 44.44% 99.28% 95.95% Left axis deviation 83.33% 97.84% 96.96% Counterclockwise depolariation 77.78% 92.81% 91.89% Left ventricular hypertrophy 22.22% 96.76% 92.23% Single ventricle physiology with morphologic left ventricle, non-inverted outlet chamber Left axis deviation 100.00% 97.84% 97.86% Dominant R in V 1 and equidiphasic RS in midprecordial leads 100.00% 100.00% 100.00% Single ventricle physiology with morphologic left ventricle, inverted outlet chamber QRS axis inferior and to right 80.00% 79.50% 79.51% Single ventricle physiology with morphologic right ventricle Right axis deviation 75.00% 86.69% 86.52% Tall stereotyped precordial R wave 75.00% 100.00% 99.65% Single ventricle with increased pulmonary blood flow Left atrial/ biatrial enlargement (bifid P or tall bifid P) 50.00% 98.92% 98.23% Single ventricle with decreased pulmonary blood flow Right atrial enlargement (tall P wave) 14.29% 99.28% 97.19% ECG: electrocardiogram; CHD: congenital heart disease; ASD: atrial septal defect; VSD: ventricular septal defect; PDA: patent ductus arteriosus; AS: aortic stenosis; CoA: coarctation of aorta; WPW: Wolff-Parkinson-White; DORV: double outlet right ventricle; PS: pulmonary stenosis DISCUSSION Two research questions formed basis of this study: how prevalent actually are the typical ECG features in congenital heart diseases, and, can ECG be used for screening of CHD? We found diverse prevalence of the established ECG features in CHDs. There is variation in terms of ECG features in different CHDs, as well as variation in prevalence of different parameters in the same CHD. For example, both ECG features (right axis deviation, tall monophasic R in V1 with early transition to rS in V2) of tetralogy of Fallot has been noticed with 100% prevalence. On the other hand, well described ECG feature of leftward P axis in sinus venosus ASD had a prevalence of only 11.1%. While studying the prevalence of these known disease-associated ECG features in population with structurally normal heart (no congenital heart disease, and no acquired heart disease), there was commendable presence of a few of these. For example, absence of Q wave in left precordial leads, a feature of congenitally corrected transposition of great arteries (CCTGA), was found in 35.3% of normal population. On statistical analysis of the study, however, most of the ECG parameters in most of heart diseases had a good specificity and accuracy in detection. Some of the features that did not have high specificity (like right axis deviation in tetralogy of Fallot, absence of Q wave in left precordial leads in CCTGA), had excellent sensitivity, with the prospect of aiding in diagnosis. Ostium secundum ASD: Absence of sinus arrhythmia was the most consistent feature in our study. Presence of rSR’ in right precordial leads and crochetage pattern in at least 1 inferior lead was found more commonly than that described by researchers earlier. 2 , 3 Furthermore, absence of sinus arrhythmia was a highly sensitive and specific parameter to diagnose hemodynamically significant OSASD, with highest accuracy of all the ECG features. Crochetage pattern in all inferior leads was the most specific (100%) one, and though it has been noted to have a poor sensitivity (11.58%) and the lowest accuracy (77.48%) of all, the accuracy stands well. On the other hand, crochetage pattern in at least 1 lead had a high specificity (99.64%) and commendable accuracy (87.94%). Both rsR’ in right precordial leads and PR prolongation had good specificity and accuracy as well. We also found left axis deviation in 1 patient without any syndromic association; this is likely to represent acquired left anterior fascicular block. 15 Hence, absence of sinus arrhythmia along with rSR’ pattern in right precordial leads and crochetage in at least one lead can be well used for screening of hemodynamically significant OSASD by ECG, with good accuracy in detection, and a highly specific crochetage in all inferior leads will aid in ruling in the diagnosis. Sinus venosus ASD Only ECG parameter described as hallmark of sinus venosus ASD (SVASD) in literature, leftward P axis, was seen only in 11.1% of patients, compared to 46% reported by Davia et al. 5 This parameter turned out to be specific and accurate, but poorly sensitive. Therefore, absence of leftward P axis (or presence of normal P axis) cannot be used to rule out SVASD in a patient with clinical features suggestive of a pre-tricuspid shunt. On the contrary, presence of this feature will act in favour of diagnosis of SVASD. We also detected leftward P axis in a patient with secundum ASD without any related syndromic association, making use of P axis as a sole marker for type of ASD even less reliable. Atrioventricular septal defect Most consistent feature was prolonged PR interval, with a prevalence of 73.9% as compared to 50% described by Jacobsen et al. 6 As per prevalence, this was followed by extreme left axis deviation (65.2%, mostly seen in association of Down syndrome in our study group) and counterclockwise depolarization (34.8%). PR prolongation also had highest sensitivity (73.91%) of all; extreme left axis deviation was most specific (100.00%) and accurate (97.34%). Good accuracy was observed in other parameters: left axis deviation (97.02%), PR prolongation (96.35%) and counterclockwise depolarization (88.37%). All the parameters had good specificity as well. Hence constellation of these features can be effectively used to screen for presence of atrioventricular septal defect, including ostium primum ASD, with good accuracy. Presence of phenotypic features of Down syndrome should also be taken in consideration. Post-tricuspid shunt (VSD/ PDA): Most prevalent ECG feature was large equiphasic RS waves in midprecordial leads (Katz-Wachtel phenomenon), found in 86.4% patients in our study, as compared to 97.1% described by Sarmila et al. 7 Katz-Wachtel phenomenon also had the highest sensitivity (86.41%) of all, with excellent specificity (100%) and accuracy (96.33%). Sensitivity of other parameters was not so good, but all of them had high specificity; specificity of signs of LVVO, signs of left atrial enlargement and signs of biatrial enlargement being 93.53%, 98.92% and 99.28% respectively. Signs of LVVO including Q wave in V 5 /V 6 had a commendable accuracy of 86.09%, whereas that of left atrial enlargement was 83.46%. Thereafter, presence of large equiphasic RS waves in midprecordial leads can be used as a screening tool for detection of hemodynamically significant post-tricuspid shunts. Simultaneous presence of signs of LVVO including Q wave in lead V 5 /V 6 and signs of left atrial enlargement, if found, will ascertain the diagnosis more. LVOT obstruction (severe AS/ severe CoA): Shah et al reported ECG evidence of left ventricular hypertrophy (LVH) in 29.4% and LV strain pattern in 20.6% patients. 8 Though we found LVH with a greater prevalence (41.2%), prevalence of LV strain is lower in our study (11.7%). Both LVH and LV strain turned out to have low sensitivity. On the contrary they had excellent specificity, specificity of LVH being 96.76% and that of LV strain being 99.64%. Both had good accuracy; signs of LVH 93.56% accurate and LV strain 94.58% accurate. Hence, presence of LVH with or without LV strain pattern in 12 lead ECG will be helpful in narrowing down diagnosis towards significant LVOT obstruction with good accuracy. But absence of these cannot be used to rule out these heart defects. Tetralogy of Fallot (TOF): Of all the CHDs included in our study, TOF was most consistent with established ECG features, with 100% patients showing monophasic R in V1 with early transition in V2, and right axis deviation. This is also at par with the result of a previous study that described right axis deviation in 96%. 9 However right axis deviation was also noted in ECG of 13.3% patients with structurally normal heart, despite taking in account age-related changes in ECG axis during evaluation. No particular cause of this could be assigned. Both the ECG parameters were 100% sensitive in detection of TOF. While specificity of early transition was 100%, specificity of right axis deviation was lower (86.69%). Hence, in a cyanotic patient, presence of these two findings on ECG can be safely used to make a provisional diagnosis of classic tetralogy of Fallot. Congenitally corrected transposition of great arteries (CCTGA): Absence of Q wave in left precordial leads (LPL) was seen in 100% patients, but simultaneous presence of Q in right leads (RPL) was in only one-third (36.4%). One study reported both of these in 100% patients. 10 Absence of Q wave in LPL, though was 100% sensitive according to our study, had a lower specificity. On the contrary, presence of Q wave in RPL had a poor sensitivity (36.36%) but an excellent specificity (99.28%). Three other ECG parameters also had good specificity: upright T wave in all precordial leads (99.64%), complete heart block (99.28%) and any degree of atrioventricular block (97.12%). All the parameters were highly accurate except absence of Q wave in LPL. Hence absence of Q wave in LPL (sensitive) along with one or more of the other specific and accurate parameters can be used safely for detection of CCTG; a point to highlight here would be the need of combining at least one of the specific features with the sensitive parameter. Severe pulmonary stenosis (intact ventricular septum): We noted tall monophasic R/qR in V1 lead in 100% of the patients, followed closely by right axis deviation in 90.6% patients. Bassingthwaighte et al reported presence of tall monophasic R wave in V1 in 80%. 12 The 3 patients in our study who did not have right axis deviation in frontal leads had left axis deviation, and all of them had Noonan syndrome, keeping at par with known feature of the syndrome. We also found ECG estimated gradient of RVOT (voltage of R wave in lead V1 in mm multiplied by 15, expressed in mm Hg) coinciding with doppler derived gradient in 84.4% patients. After analysis, tall monophasic R/qR in V1 lead was 100% sensitive, specific and accurate in our study. While right axis deviation had commendable sensitivity (90.62%) and specificity (91.37%), tall peaked P wave and wide QRS-T angle/ strain pattern had excellent specificity but poor sensitivity. Accuracy of these three features was good (> 90%). However, the two highly sensitive and specific features, namely right axis deviation and tall monophasic R/qR in V1 are suggestive of right ventricular hypertrophy, and RVH is not exclusive to this group of CHD. Hence, simultaneous presence of any or both of the other two specific and accurate (but not very sensitive) parameters, tall peaked P wave and wide QRS-T angle/strain, along with any/both features of RVH, can be used to detect severe PS/intact ventricular septum with confidence, in an acyanotic patient. The ECG estimated gradient can also be used by physicians to anticipate RVOT gradient. Ebstein’s anomaly: 100% patients in our study had prolonged PR interval, compared to Assenza et al who found it in 17% of the patients. 13 We found this to be highly sensitive (100%), specific (98.20%) and accurate (98.25%). Other three parameters (tall P wave, right bundle branch block, WPW preexcitation/ delta wave) though had low sensitivity, had very good specificity (≥ 99%) and accuracy (> 97%). Right bundle branch block pattern and WPW pre-excitation pattern were mutually exclusive. Therefore, prolonged PR interval and tall P wave, along with either RBBB or WPW pre-excitation pattern, can be very well used as a screening tool to detect Ebstein anomaly, with additional emphasis by with clinical features like multiple heart sounds. DORV with subaortic VSD and no PS (DORV, VSD type): We found higher prevalence of prolonged PR interval (50%), in comparison to Krongrad et al (26%). 14 All 3 ECG parameters (prolonged PR interval, left axis deviation and counterclockwise depolarization) in diagnosis of DORV/subaortic VSD/no PS had good specificity and accuracy (> 90%) but poor sensitivity (< 50%). Hence, these features can be used as a screening tool to rule in DORV/VSD type, but absence of these will not help to rule out the disease. DORV with subaortic VSD and PS (DORV, TOF type): In this group too we found higher prevalence of prolonged PR interval (52.6%), in comparison to Krongrad et al (26%). 14 The parameter with highest sensitivity was vertical/right QRS axis (sensitivity 89.47%) but it had lower specificity and accuracy. On the other hand, prolonged PR interval and counterclockwise depolarization had good specificity and accuracy, with low sensitivity. Thereafter, constellation of sensitive vertical/right QRS axis and any or both of the other two specific features can be safely used to detect DORV/subaortic VSD/PS by ECG screening, in a cyanotic patient. DORV with subpulmonary VSD (DORV, TGA type, Taussig-Bing anomaly): As prolonged PR interval had zero sensitivity in this group, it cannot be used as a screening parameter. Clockwise depolarization had good specificity and accuracy (94% or more), but lower sensitivity (80%). Vertical/right QRS axis had moderate sensitivity and specificity (near 80%). Hence, in the absence of a highly sensitive ECG parameter, clockwise depolarization and vertical/QRS axis can be used together to rule in DORV/ subpulmonary VSD in a relevant clinical background (cyanosis, increased pulmonary blood flow), but absence of these cannot be safely used to rule out this. Finally, taking in account all variants of double outlet right ventricle, our study shows that PR prolongation along with subgroup-specific pattern of QRS axis and limb lead depolarization can aid in screening of this cohort of CHD, though these is lack of literature looking into prevalence pattern of these. Tricuspid atresia: Hallmark features in ECG like left axis deviation and counterclockwise depolarization were found in 83.3% and 77.8% patients respectively. Tall P wave and left ventricular hypertrophy was even less prevalent. We did not find any previous study to compare. All the ECG parameters showed excellent (90% or more) specificity and accuracy, but only moderate sensitivity. Most sensitive of these was left axis deviation (83.33%), followed by counterclockwise depolarization (77.78%). Tall P wave had highest specificity (99.28%) and left axis deviation was most accurate (96.96%). Constellation of sensitive features like left axis deviation and counterclockwise depolarization in limb leads in a patient of cyanotic congenital heart disease, along with one or more other specific features like tall P wave and LVH, if found, can be used to rule in tricuspid atresia. However, absence of only poorly sensitive tall P wave and LVH cannot be used to rule out tricuspid atresia. Single ventricle: This group of congenital heart diseases have the maximum variety of subgroups according to anatomical and hemodynamic variations, with each subgroup described to have some pathognomonic ECG findings. To our knowledge, this is the first study on prevalence of ECG patterns in this group of CHDs. When sub-grouped as anatomical variations (morphological RV vs LV or inverted vs non-inverted outlet chamber), the established ECG features had quite high prevalence; for example, left axis deviation in morphological LV with non-inverted outlet chamber (100%) and inferior/ rightward QRS axis in morphological LV with inverted outlet chamber (80%). In evaluation of single ventricle physiology with morphologic left ventricle and non-inverted outlet chamber, both left axis deviation and dominant R in V 1 and equidiphasic RS in midprecordial leads were highly sensitive and specific (≥ 97%). In evaluation of single ventricle physiology with morphologic left ventricle and inverted outlet chamber, the established ECG parameter of inferior and rightward QRS axis had moderate sensitivity and specificity (around 80%). In evaluation of single ventricle physiology with morphologic right ventricle, tall stereotyped precordial wave was 100% specific, and right axis deviation 86.69% specific. Both had lower sensitivity of 75%. However, atrial enlargement pattern according to pulmonary blood flow (left atrial enlargement in increased pulmonary blood flow or right atrial enlargement in decreased pulmonary blood flow) was seen with less prevalence, poor sensitivity, but good specificity. Hence, it will be difficult to use these features only to rule out the CHD, but if it is present in a patient with other ECG features of single ventricle, it can be used to comment on increased or decreased pulmonary blood flow. After considering all, our analysis remains: constellation of features can be safely used to comment on anatomical/ morphological type of univentricular CHD, though the same will be less applicable to screen pattern of pulmonary blood flow. If clinical features of increased or decreased pulmonary blood flow is taken in account along with chest x-ray (pulmonary oligemia vs plethora), ECG will be more helpful to raise alarm about suspicion of this group of congenital heart disease. Relatively small sample size in this group also precludes a strong comment. Formulating differential diagnoses from ECG: Further, we realise that isolated ECG features can be common to more than one heart defect, for example prolonged PR interval. How would then we know what disease the patient has by looking at ECG strip? Here, we formulate a different approach. If considered individually, or if found in the absence of conglomeration of disease-specific features, the ECG findings can still be useful to establish a list of differential diagnoses, and thereafter to narrow down the diagnosis taking help of supporting clinical findings (Table 4 ). Table 4 Differential diagnosis of abnormal ECG feature (the ones found in multiple CHDs) Differential diagnosis: prolonged PR interval Differential diagnosis: left axis deviation Differential diagnosis: right axis deviation (including vertical/right QRS axis) Differential diagnosis: left atrial enlargement Differential diagnosis: right atrial enlargement 1. Hemodynamically significant OSASD 1. Atrioventricular septal defect (including ostium primum ASD) 1. Tetralogy of Fallot 1. Hemodynamically significant (moderate to large) post tricuspid shunt (VSD, PDA) 1. Severe pulmonary stenosis (intact ventricular septum) 2. Atrioventricular septal defect (including ostium primum ASD) 2. DORV/ subaortic VSD/ no PS (DORV, VSD type) 2. Severe pulmonary stenosis/ intact ventricular septum 2. Single ventricle physiology with increased pulmonary blood flow 2. Ebstein’s anomaly 3. Ebstein’s anomaly 3. Tricuspid atresia 3. DORV/ subaortic VSD/ severe PS (DORV, TOF type) 3. Tricuspid atresia 4. Double outlet right ventricle, all anatomical variants 4. Single ventricle physiology with morphologic left ventricle and non-inverted outlet chamber 4. DORV/ subpulmonary VSD (DORV, TGA type, Taussig-Bing anomaly) 4. Single ventricle physiology with decreased pulmonary blood flow 5. Single ventricle physiology with morphologic right ventricle ECG: electrocardiogram; CHD: congenital heart disease; ASD: atrial septal defect; VSD: ventricular septal defect; PDA: patent ductus arteriosus; AS: aortic stenosis; CoA: coarctation of aorta; WPW: Wolff-Parkinson-White; DORV: double outlet right ventricle; PS: pulmonary stenosis How we arrive diagnosis from the differential is a systematic approach. PR prolongation is highly specific for the 4 diseases, with > 95% specificity and accuracy. Of these DORV/ subaortic VSD/ PS (DORV, TOF type) is cyanotic, and DORV/ subpulmonic VSD (DORV, TGA type) presents with mild cyanosis and features of increased pulmonary blood flow. Other than these two, rest of the CHDs are acyanotic. Thereafter, if PR prolongation (age-specific PR interval to be taken in account) is noticed in ECG with pertinent clinical scenario, keeping in mind the list of differential diagnoses, specific features of CHDs are to be sought for. Let us look at the list under left axis deviation. Tricuspid atresia and the variant of single ventricle with decreased pulmonary blood flow will have cyanosis. On the contrary, AVSD and DORV/VSD type and single ventricle with increased pulmonary blood flow will present with signs and symptoms of increased pulmonary blood flow. Extreme left axis is again 100% specific for AVSD. Hence, combining left axis deviation with other specific ECG features of each CHD, and clinical signs, physicians will be able put a finger on diagnosis, even in the absence of immediate echocardiography. Right axis deviation has more specificity in TOF and severe PS/ intact ventricular septum as compared to rest three. Classic TOF and DORV/subaortic VSD/ PS both are cyanotic heart diseases with similar clinical presentation. Associated ECG features of respective CHDs along with right axis deviation in a cyanotic patient therefore not only can diagnose TOF physiology but also differentiate between these two. Early transition pattern favours diagnosis of TOF, whereas counterclockwise depolarization and prolonged PR interval are in favour of DORV/VSD/PS. Persistence of counterclockwise depolarization in the form of q wave in lead I and aVL even when the QRS axis is vertical/ rightward is a distinctive feature of DORV/VSD/PS whereas q in lead I and aVL is virtually unheard of in classic TOF. Single ventricle with morphological RV and decreased pulmonary blood flow will also have cyanosis, and tall stereotyped precordial R wave is a pointer towards this. DORV/subpulmonic VSD (DORV, TGA type) will have mild cyanosis with features of increased pulmonary blood flow, and associated clockwise depolarization. An important differential of this group in severe PS/intact ventricular septum, suspicion about which wil be raised by simultaneous presence of tall P wave, monophasic R/qR pattern in V1 (with no early transition pattern), and wide QRS/T angle or strain pattern. Both the CHDs, for which bifid and wide P wave (P mitrale), suggestive of left atrial enlargement, has been found to be specific (though not so sensitive), present with features of increased pulmonary blood flow. Clinical findings of murmur would act as a first pointer towards post tricuspid shunt. Presence of other specific ECG features will help as well. For example, large equiphasic RS in midprecordial leads (Katz-Wachtel phenomenon) and sign of left ventricular volume overload, if found, helps to rule in post-tricuspid shunt. On the other hand, depending on the morphological type of single ventricle and anatomical variant, specific ECG features will aid in diagnosis. Left axis deviation and dominant R in V1 and equidiphasic RS in midprecordial leads will point towards single ventricle physiology with morphologic left ventricle, non-inverted outlet chamber. Tall stereotyped precordial R wave will point towards single ventricle physiology with morphologic right ventricle. For the CHDs with right atrial enlargement, single ventricle with decreased pulmonary blood flow patients will definitely have some degree of cyanosis, with variable presence of cyanosis in other CHDs. Other associated ECG features will aid to narrow down the diagnosis from this list. For example, severe PS/intact ventricular septum has other specific features like right axis deviation and tall monophasic R/qR in V1. Ebstein’s anomaly has specific features like PR prolongation, WPW preexcitation/ delt wave and right bundle branch block pattern (last two are mutually exclusive). To summarise, constellation of sensitive and specific features, as described in the discussion section, will aid in detection. Therefore, ECG can be used as a screening tool to prepare a list of possible differential diagnosis, as well as to raise suspicion about presence of a certain CHD. Pertinent clinical scenario, if noted, will further strengthen this screening. CONCLUSION AND LIMITATION Reflecting back on the research questions, prevalence pattern of established well-known specific electrocardiogram features in common congenital heart diseases has been assessed in this research. Varying prevalence of ECG findings in some CHDs has also been noted. Analysis of study results in terms of sensitivity, specificity and accuracy guides to the conclusion that 12 lead ECG can be used as a screening tool to raise suspicion about presence of certain common congenital heart diseases. Using constellation of features will strengthen this screening purpose more, combining sensitive and specific parameters. Therefore, it can be proposed that constellation of ECG features, along with simple screening tools like pulse oximetry and clinical findings, will aid in screening of suspected congenital heart diseases by primary care physicians and pediatricians, in the outpatient practice. This will further prompt referral to cardiology service, specifically from areas where advanced investigation tools like echocardiography may not be readily available. A faster referral and prompt diagnosis will be of utmost importance considering the burden of congenital heart disease. Limitations of the study : Limited duration of the study (18 months) and recruitment of only new patients who/ whose parents gave consent leading to limited number of patients in general, and less prevalence of some congenital heart diseases like single ventricle and sinus venosus ASD led to recruitment of a smaller number of patients with these diseases in the study. We encourage further larger multicentre studies with longer duration to establish population prevalence of ECG features, and strengthen the aim of using 12 lead ECG as a screening tool for diagnosis of congenital heart diseases. Declarations Competing interest: None. Acknowledgements: None Funding: This study has received no external funding. Disclosure of interest: None Data availability statement: The data used to support the findings of this study are included within the article. References Perloff JK, Marelli A. Perloff’s clinical recognition of congenital heart disease: Expert consult - online and print. 6th ed. London, England: W B Saunders; 2012 Refaei M, Islam S, Mackie AS, Atallah J. Correlation of electrocardiogram parameters and hemodynamic outcomes in patients with isolated secundum atrial septal defects. Ann Pediatr Cardiol. 2017;10(2):4103 0974–2069. Cohen JS, Patton DJ, Giuffre RM. The crochetage pattern in electrocardiograms of pediatric atrial septal defect patients. Can J Cardiol. 2000;16(10):1241–7. Shen L, Liu J, Li J-K, Xu M, Yuan L, Zhang G-Q, et al. The significance of crochetage on the R wave of an electrocardiogram for the early diagnosis of pediatric secundum atrial septal defect. Pediatr Cardiol. 2018;39(5):1031–5 Davia JE, Cheitlin MD, Bedynek JL. Sinus venosus atrial septal defect: Analysis of fifty cases. Am Heart J. 1973;85(2):177–85. Jacobsen JR, Gillette PC, Corbett BN, Rabinovitch M, McNamara DG. Intracardiac electrography in endocardial cushion defects. Circulation. 1976;54(4):599–603. Sarmila B, Iskandar B, Daud D. Diagnostic value of electrocardiography for ventricular septal defect. Paediatr Indones. 2019;59(2):87–91. Shah AS, Chin CW, Vassiliou V, Cowell SJ, Doris M, Kwok TC, et al. Left ventricular hypertrophy with strain and aortic stenosis. Circulation. 2014;130:1607–1616. Roberts DL, Wagner HR, Lambert EC. The electrocardiogram in tetralogy of Fallot. J Electrocardiol. 1972;5(2):155-61. Victorica BE, Miller BL, Gessner IH. Electrocardiogram and vectorcardiogram in ventricular inversion (corrected transposition. Am Heart J. 1973;86:733–744. Walker WJ, Cooley DA, Mc ND, Moser RH. Corrected transposition of the great vessels, atrioventricular heart block, and ventricular septal defect: a clinical triad. Circulation. 1958;17:249–254 Bassingthwaighte JB, Parkin TW, Dushane JW, Wood EH, Burchell HB. The electrocardiographic and hemodynamic findings in pulmonary stenosis with intact ventricular septum. Circulation. 1963;28: 893–905. Assenza GE, Valente AM, Geva T, Graham D, Pluchinotta FR, Sanders SP, et al. “QRS duration and QRS fractionation on surface electrocardiogram are markers of right ventricular dysfunction and atrialization in patients with Ebstein anomaly” [Eur Heart J 2012;34:191-200, doi:10.1093/eurheartj/ehs362]. Eur Heart J. 2013;34(8):624–624. Krongrad E, Ritter DG, Weidman WH, Dushane JW. Hemodynamic and anatomic correlation of electrocardiogram in doubleoutlet right ventricle. Circulation. 1972;46:995– 1004. Harrison DC, Morrow AG. Electrocardiographic evidence of left axis deviation in patients with defects of the atrial septum of the secundum type. N Engl J Med. 1963;269:743–745. Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6106927","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":433515699,"identity":"392d4fbb-7470-429d-a86e-37b99bcf2306","order_by":0,"name":"Somrita Laha","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA6ElEQVRIiWNgGAWjYLCCBAYGGQYJBsYHQDYPH3FaEhh4gFqYDUBa2Ii1BqSFTQLEJqhFvr077cPDH3Y8/LObn1V+zbGTYWNgfvjoBh4tBmfObp6RkJDMI3HnmNlt2W3JQIexGRvn4NMikbsZ6BdmHoYbCWa3JbcxA7XwsEnj0yI/A6ylnkf+Rvq3Yslt9YS1MNwAaznMY3Ajx4zx47bDhLWA/MKQkHacx/BGTrE047bjPGzMBPwi3967mfGHTbWc3I30jR9/bqu252dvfvgYr8OQATAQQCSxykGA8QcpqkfBKBgFo2DEAABNY0O9RRduHwAAAABJRU5ErkJggg==","orcid":"","institution":"NH-Rabindranath Tagore International Institute of Cardiac Sciences","correspondingAuthor":true,"prefix":"","firstName":"Somrita","middleName":"","lastName":"Laha","suffix":""},{"id":433515700,"identity":"bb41851e-5320-491a-944e-a70f5a922b96","order_by":1,"name":"Debasree Gangopadhyay","email":"","orcid":"","institution":"NH-Rabindranath Tagore International Institute of Cardiac Sciences","correspondingAuthor":false,"prefix":"","firstName":"Debasree","middleName":"","lastName":"Gangopadhyay","suffix":""},{"id":433515701,"identity":"f25fd733-417f-4724-bcbc-314e710fd0a6","order_by":2,"name":"Mahua Roy","email":"","orcid":"","institution":"NH-Rabindranath Tagore International Institute of Cardiac Sciences","correspondingAuthor":false,"prefix":"","firstName":"Mahua","middleName":"","lastName":"Roy","suffix":""},{"id":433515702,"identity":"40ae802f-f464-423b-a804-cc4bb1ebe138","order_by":3,"name":"Pooja Sinha","email":"","orcid":"","institution":"Rainbow Children’s Heart Institute","correspondingAuthor":false,"prefix":"","firstName":"Pooja","middleName":"","lastName":"Sinha","suffix":""}],"badges":[],"createdAt":"2025-02-25 16:23:10","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6106927/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6106927/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":79288185,"identity":"4a1e9f79-cb8c-46a3-92d1-e1dcbf0331d3","added_by":"auto","created_at":"2025-03-26 15:19:51","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":148915,"visible":true,"origin":"","legend":"\u003cp\u003eGraphical abstract\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-6106927/v1/606b577069919487551165e8.png"},{"id":79288187,"identity":"0b633963-c725-41dc-81ef-cd92ac86f777","added_by":"auto","created_at":"2025-03-26 15:19:51","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":173977,"visible":true,"origin":"","legend":"\u003cp\u003eDistribution of congenital heart diseases in study population\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-6106927/v1/c63d69b1b17dfd06a4dd0978.png"},{"id":79290721,"identity":"dfb97710-a419-4f6a-b841-1aecd8e6f0a5","added_by":"auto","created_at":"2025-03-26 15:43:52","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1984896,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6106927/v1/c618bc16-80cc-48a3-b671-37d7803424a0.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eRole of electrocardiogram in detecting congenital heart disease:prevalence and diagnostic accuracy of pathognomonic features\u003c/p\u003e","fulltext":[{"header":"KEY MESSAGES","content":"\u003cul\u003e\n \u003cli\u003eWhat is already known about this research?\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eThere are isolated studies on ECG pattern of different congenital heart diseases. There is also description of individual ECG features as classic finding of certain CHDs in literature.\u0026nbsp;\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003eWhat this study adds?\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eTo our knowledge, this is the first study that holistically approaches all common structural heart defects to investigate actual prevalence of abnormal ECG. This study has also included an extensive statistical analysis to provide sensitivity, specificity and accuracy of each and every abnormal ECG feature in diagnosis of CHD, which none of the previous studies have done.\u003c/p\u003e"},{"header":"INTRODUCTION","content":"\u003cp\u003eCongenital heart diseases (CHD) account for nearly one third of all major congenital anomalies. Not to forget, a huge number of these defects, if diagnosed in appropriate time, are repairable leading to improved quality of life. Diagnosis of CHD is a multistep process, comprising of history, clinical examination, chest roentgenogram (CXR), electrocardiogram (ECG), echocardiography, advanced imaging studies like computed tomography (CT) and magnetic resonance imaging (MRI), and invasive procedures like cardiac catheterization.\u003c/p\u003e \u003cp\u003eECG changes in congenital heart diseases are explained by multiple factors, like hemodynamic changes, ventricular preponderance, anatomy of conduction system etc. Taking in account these factors, some ECG findings are seen characteristically clustered in certain CHDs, described as \u0026lsquo;sine qua non\u0026rsquo; of the related defects; for example, extreme left axis deviation in atrioventricular septal defect, or early transition of RS complex in tetralogy of Fallot (TOF).\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e By pointing out abnormalities in ECG, it is often feasible to put a finger at the possible diagnosis, or narrow down the differential diagnoses. However, before deducing an anatomical or morphological diagnosis from a strip of ECG, it is extremely important to know prevalence, sensitivity, specificity and diagnostic accuracy of the findings associated with a specific defect.\u003c/p\u003e \u003cp\u003eOver the past decades, a handful of studies have explored the spectrum of ECG features in some of the CHDs. But, most of these studies have focussed on a single CHD or a group of CHDs with common hemodynamics. Furthermore, only a few diseases have grabbed the attention of researchers in past, and no study did include all CHDs holistically or looked into the diagnostic accuracy of ECG in structural heart disease.\u003c/p\u003e"},{"header":"AIM AND OBJECTIVE","content":"\u003cp\u003eThe primary objective of the research was to study the pattern of ECG features in common CHDs, and to assess how commonly established ECG changes are found in these patients. We considered the ECG abnormalities that have been described as classical for each CHD in literature, while assessing pattern. Along with the prevalence thus stated, we sought out to note commonly recurring deviation from known pattern, if any found. We also extended the study population to controls with structurally normal heart, to find out if any of these pathognomonic ECG pointers were noted in them. Thereafter, our final objective was to deduce sensitivity, specificity and diagnostic accuracy of ECG patterns in associated CHDs.\u003c/p\u003e "},{"header":"METHODS","content":"\u003cp\u003eThe research was planned as a cross-sectional, observational, descriptive study. Study period was 18 months (August 2021 to January 2023).\u003c/p\u003e\n\u003ch3\u003eInclusion criteria\u003c/h3\u003e\n\u003cp\u003ePatients with isolated CHDs as described below were included in the study.\u003c/p\u003e\n\u003cp\u003e\u003cspan\u003e1. Hemodynamically significant ostium secundum atrial septal defects (OSASD) defined by presence of dilated right atrium and right ventricle\u003cbr\u003e\u003c/span\u003e\u003cspan\u003e2. Sinus venosus atrial septal defects (ASD)\u003cbr\u003e\u003c/span\u003e\u003cspan\u003e3. Atrioventricular septal defects (AVSD), including ostium primum ASD\u003cbr\u003e\u003c/span\u003e\u003cspan\u003e4. Hemodynamically significant (moderate to large) post-tricuspid shunt lesions, ventricular septal defect (VSD) and patent ductus arteriosus (PDA), defined by left ventricle end-diastolic diameter of more than +\u0026thinsp;2 z scores\u003cbr\u003e\u003c/span\u003e\u003cspan\u003e5. Significant left ventricular outflow tract obstructive (LVOTO) lesions: severe aortic stenosis (AS) (defined by a peak velocity across the aortic valve of \u0026ge;\u0026thinsp;4.0 m/s or a mean gradient across the valve of \u0026ge;\u0026thinsp;40 mm Hg) and significant coarctation of aorta (CoA) (defined by any of these: gradient across the defect of more than 20 mm Hg, left ventricular hypertrophy, upper limb hypertension according to age and sex)\u003cbr\u003e\u003c/span\u003e\u003cspan\u003e6. Classic tetralogy of Fallot (TOF)\u003cbr\u003e\u003c/span\u003e\u003cspan\u003e7. Congenitally corrected transposition of great arteries (CCTGA)\u003cbr\u003e\u003c/span\u003e\u003cspan\u003e8. Severe pulmonary stenosis (PS), defined by peak gradient across valve more than 64 mm Hg\u003cbr\u003e\u003c/span\u003e\u003cspan\u003e9. Ebstein\u0026rsquo;s anomaly\u003cbr\u003e\u003c/span\u003e\u003cspan\u003e10. Double outlet right ventricle (DORV)\u003cbr\u003e\u003c/span\u003e\u003cspan\u003e11. Tricuspid atresia\u003cbr\u003e\u003c/span\u003e\u003cspan\u003e12. Single ventricle/ univentricular heart\u003cbr\u003e\u003c/span\u003e\u003c/p\u003e\n\u003cp\u003eExclusion criteria\u003c/p\u003e\n\u003cp\u003eAny patient with more than one congenital heart defect among those described above, or any other complex structural heart disease were excluded from the study, as it would be difficult to apply classical ECG findings in simultaneous presence of multiple CHDs (for eg, OSASD and VSD). Shunt lesions with pulmonary vascular obstructive disease leading to reversal of shunt (Eisenmenger syndrome) were excluded from the study, because this group has varied ECG depending not only the underlying hemodynamics, but also primary defect.\u003c/p\u003e\n\u003cp\u003ePatients attending the Pediatric Cardiology out-patient department (OPD) during the study period were included, taking in account presence of the inclusion and exclusion criteria as above. The patients were grouped according to the type of CHD, depending on final diagnosis by echocardiography. To avoid repeated inclusion of the same patient during follow up visit as a fresh case, only patients attending the OPD for the first time were included. The study assessed how many and which established ECG features were present in patients with specific CHDs. At the end, the prevalence of each ECG feature in each CHD group was calculated as a percentage of the total patients in that group, providing insight into how common specific ECG findings are in these conditions. The particular ECG findings taken in account for diseases, were also sought for in the control population, and prevalence of these expressed as percentage.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eControls\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe patients attending pediatric cardiology OPD who were detected to have structurally normal heart (including those with a patent foramen ovale or bicuspid aortic valve with no aortic stenosis or aortic regurgitation) were taken as control (normal) population, to aid in our statistical analysis.\u003c/p\u003e\n\u003cp\u003eData was analysed using SPSS software, version 26.0. All continuous variables were expressed as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD (standard deviation) and qualitative variables as numbers and percentages. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy was calculated for each ECG parameter in each group of congenital heart disease.\u003c/p\u003e\n\u003cp\u003eThe study was carried out in accordance with relevant guidelines and regulations. Study protocol was approved by the institutional research committee and ethics committee. Written informed consent was taken from the patients (older than 7 years of age) or parents/guardians for voluntary participation in the study, after informing them about every detail pertaining to the study process, procedures and requirements in a language that they 18 understand fully. The consent was collected after providing appropriate answers with adequate details for all questions of the participants/ guardians.\u003c/p\u003e"},{"header":"RESULTS","content":"\u003cp\u003eA total of 473 patients and 278 controls, who gave consent to participate in the study, were included. Mean age of patients was 6.62\u0026thinsp;\u0026plusmn;\u0026thinsp;1.36 years (range 7 days to 56 years). 55.6% and 54.7% of patients group and control group comprised of male, and the rest female. Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e illustrates distribution of CHDs in our study population.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e shows prevalence of different ECG features in each congenital heart disease, whereas Table \u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e shows prevalence of the same abnormal ECG pointers in control population.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePrevalence of different established ECG features in congenital heart diseases, and comparison of the same with other available studies\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCongenital heart disease\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eECG feature of the CHD\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePrevalence percentage of the ECG feature in that particular group of CHD\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePrevalence percentage of specific ECG feature in CHD in previous study\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAny new feature noted in ECG than that described in literature\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003eHemodynamically significant Ostium secundum ASD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAbsence of sinus arrhythmia\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e97.9%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo available study\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003eLeft axis deviation in 1 patient (non-syndromic)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePR prolongation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e45.3%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo available study\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003erSR\u0026rsquo; in right precordial leads\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e74.7%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e54% (Refaei et al, 2017)\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCrochetage pattern in at least 1 inferior lead\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e53.7%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e31.7% (Cohen et al, 2000)\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCrochetage pattern in all inferior leads\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e17.9%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e28.13% (Shen et al, 2018)\u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSinus venosus ASD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLeftward P axis (less than 30\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11.1%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e46% (Davia et al, 1973)\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003eAtrioventricular septal defect (including ostium primum ASD)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLeft axis deviation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e34.8%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo available study\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"3\" rowspan=\"4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eExtreme left axis deviation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e65.2%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCounterclockwise depolarization\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e34.8%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo available study\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePR prolongation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e73.9%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e50% (Jacobsen et al, 1976)\u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003eHemodynamically significant (moderate to large) post tricuspid shunt (VSD, PDA)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSign of left atrial enlargement\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e41.7%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo available study\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"3\" rowspan=\"4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSign of biatrial enlargement\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e13.6%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo available study\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSign of left ventricular volume overload\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e66.1%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo available study\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLarge equiphasic RS in midprecordial leads (Katz-Wachtel phenomenon)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e86.4%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e97.1% (Sarmila et al, 2019)\u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eLeft ventricular outflow tract obstruction (severe AS, significant CoA)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSign of left ventricular hypertrophy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e41.2%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e29.4% (Shah et al, 2014)\u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eECG strain\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11.7%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e20.6% (Shah et al, 2014)\u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eTetralogy of Fallot\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRight axis deviation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e100%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e96% (Roberts et al, 1972)\u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTall monophasic R in V\u003csub\u003e1\u003c/sub\u003e with early transition to rS in V\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e100%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo available study\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003eCongenitally corrected transposition of great arteries\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAbsence of Q wave in left precordial leads\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e100%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e100% (Victorica et al, 1973)\u003csup\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"4\" rowspan=\"5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePresence of Q wave in right precordial leads\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e36.4%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e100% (Victorica et al, 1973)\u003csup\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eUpright T wave in all precordial leads\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e54.5%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e80% (Victorica et al, 1973)\u003csup\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAny degree of atrioventricular block\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e63.6%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e75% (Walker et al, 1958)\u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eComplete heart block\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e27.3%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e30% (Walker et al, 1958)\u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003eSevere pulmonary stenosis (intact ventricular septum)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTall peaked P wave\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e53.1%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo available study\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003eLeft axis deviation in 3 patients of Noonan syndrome\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTall monophasic R/ qR in V\u003csub\u003e1\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e100%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e80% (Bassingth-waighte et al, 1963)\u003csup\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRight axis deviation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e90.6%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo available study\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWide QRS-T angle/ strain\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9.4%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo available study\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDoppler gradient similar to ECG estimated gradient\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e84.4%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo available study\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003eEbstein\u0026rsquo;s anomaly\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTall P wave\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e28.6%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e15% (Assenza et al, 2013)\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"3\" rowspan=\"4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eProlonged PR interval\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e100%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e17% (Assenza et al, 2013)\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRight bundle branch block\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e57.1%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e49% (Assenza et al, 2013)\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWPW preexcitation/ delta wave\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e28.6%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo available study\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eDORV with subaortic VSD, no PS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eProlonged PR interval\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e50.0%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e26% (Krongrad et al, 1972)\u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"2\" rowspan=\"3\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLeft axis deviation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e37.5%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo available study\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCounterclockwise depolarization\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e50.0%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo available study\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eDORV, subaortic VSD, severe PS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eProlonged PR interval\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e52.6%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e26% (Krongrad et al, 1972)\u003csup\u003e31\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eLeft axis deviation in 1 patient, normal QRS axis in 1 patient\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eVertical/ right QRS axis\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e89.5%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo available study\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCounterclockwise depolarization\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e57.9%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo available study\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eDORV, subpulmonary VSD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eProlonged PR interval\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo available study\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"2\" rowspan=\"3\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eVertical/ right QRS axis\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e80.0%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo available study\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eClockwise depolarization\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e80.0%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo available study\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003eTricuspid atresia\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTall P wave\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e44.4%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo available study\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003eNormal QRS axis in 2 patient, Right axis deviation in 1 patient\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLeft axis deviation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e83.3%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo available study\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCounterclockwise depolariation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e77.8%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo available study\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLeft ventricular hypertrophy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e22.2%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo available study\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eSingle ventricle physiology with morphologic left ventricle, non-inverted outlet chamber\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLeft axis deviation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e100.0%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo available study\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDominant R in V\u003csub\u003e1\u003c/sub\u003e and equidiphasic RS in midprecordial leads\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e100.0%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo available study\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSingle ventricle physiology with morphologic left ventricle, inverted outlet chamber\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eQRS axis inferior and to right\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e80.0%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo available study\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eSingle ventricle physiology with morphologic right ventricle\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRight axis deviation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e75.0%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo available study\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTall stereotyped precordial R wave\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e75.0%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo available study\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSingle ventricle with increased pulmonary blood flow\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLeft atrial/ biatrial enlargement (bifid P or tall bifid P)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e50.0%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo available study\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSingle ventricle with decreased pulmonary blood flow\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRight atrial enlargement (tall P wave)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e14.3%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo available study\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003eECG: electrocardiogram; CHD: congenital heart disease; ASD: atrial septal defect; VSD: ventricular septal defect; PDA: patent ductus arteriosus; AS: aortic stenosis; CoA: coarctation of aorta; WPW: Wolff-Parkinson-White; DORV: double outlet right ventricle; PS: pulmonary stenosis\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePrevalence of ECG features known as hallmark of different congenital heart diseases, as noted in control (normal) population\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"2\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eEstablished ECG features of common congenital heart diseases\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePrevalence in control population\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAbsence of sinus arrhythmia\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4.68%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePR prolongation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.80%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003erSR prime in right precordial leads\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6.12%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCrochetage pattern in any inferior lead\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.36%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLeftward P axis\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.07%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLeft axis deviation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.2%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCounterclockwise depolarization\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7.2%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSign of left atrial enlargement\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.1%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSign of biatrial enlargement\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.7%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSign of left ventricular volume overload\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6.5%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLarge equiphasic RS in midprecordial leads\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSign of left ventricular hypertrophy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3.2%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eECG strain (LV strain)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.36%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRight axis deviation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e13.3%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTall monophasic R in V\u003csub\u003e1\u003c/sub\u003e with early transition to rS in V\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAbsence of Q wave in left precordial leads\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e35.3%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePresence of Q wave in right precordial leads\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.7%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUpright T wave in all precordial leads\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.4%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAny degree of atrioventricular block\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3.9%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eComplete heart block\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.7%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTall peaked P wave\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.7%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTall monophasic R/ qR in V\u003csub\u003e1\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWide QRS-T angle/ strain (RV strain)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.4%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRight bundle branch block\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.1%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWPW preexcitation/ delta wave\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.7%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVertical/ right QRS axis\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e20.5%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eClockwise depolarization\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5.03%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDominant R in V\u003csub\u003e1\u003c/sub\u003e and equidiphasic RS in midprecordial leads\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTall stereotyped precordial R wave\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"2\"\u003eECG: electrocardiogram; LV: left ventricle; WPW: Wolff-Parkinson-White\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e here shows sensitivity, specificity and diagnostic accuracy of pathognomonic typical ECG features in detection of the related CHD.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eResults of statistical analysis showing diagnostic role of ECG pointers in detecting a CHD\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCongenital heart disease\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eECG feature of the CHD\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSensitivity\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSpecificity\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAccuracy\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003eLarge Ostium secundum ASD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAbsence of sinus arrhythmia\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e97.9%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e95.3%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e95.9%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePR prolongation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e45.3%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e98.2%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e84.7%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003erSR\u0026rsquo; in right precordial leads\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e74.7%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e93.9%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e89.0%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCrochetage pattern in at least 1 inferior lead\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e53.7%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e99.6%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e87.9%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCrochetage pattern in all inferior leads\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e11.6%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e100.0%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e77.5%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSinus venosus ASD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLeftward P axis (less than 30\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e11.1%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e98.9%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e96.2%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003eAtrioventricular septal defect (including ostium primum ASD)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLeft axis deviation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e34.8%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e97.8%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e97.0%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eExtreme left axis deviation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e65.2%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e100.0%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e97.3%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCounterclockwise depolarization\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e34.8%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e92.8%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e88.4%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePR prolongation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e73.9%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e98.2%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e96.4%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003eLarge Post tricuspid shunt (VSD, PDA)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSign of left atrial enlargement\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e41.8%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e98.9%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e83.5%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSign of biatrial enlargement\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e13.6%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e99.3%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e76.1%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSign of left ventricular volume overload (Q in V5/V6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e66.1%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e93.5%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e86.1%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLarge equiphasic RS in midprecordial leads (Katz-Wachtel phenomenon)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e86.4%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e100.0%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e96.3%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eLeft ventricular outflow tract obstruction (severe AS, significant CoA)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSign of left ventricular hypertrophy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e41.18%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e96.76%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e93.56%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eECG strain\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e11.76%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e99.64%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e94.58%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eTetralogy of Fallot\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRight axis deviation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e100.00%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e86.69%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e90.31%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTall monophasic R in V\u003csub\u003e1\u003c/sub\u003e with early transition to rS in V\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e100.00%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e100.00%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e100.00%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003eCongenitally corrected transposition of great arteries\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAbsence of Q wave in left precordial leads\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e100.00%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e64.75%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e66.09%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePresence of Q wave in right precordial leads\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e36.36%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e99.28%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e96.89%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eUpright T wave in all precordial leads\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e54.55%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e99.64%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e97.92%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAny degree of atrioventricular block\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e63.64%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e97.12%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e95.85%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eComplete heart block\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e27.27%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e99.28%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e96.54%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003eSevere pulmonary stenosis (intact ventricular septum)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTall peaked P wave\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e53.12%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e99.28%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e94.52%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTall monophasic R/ qR in V\u003csub\u003e1\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e100.00%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e100.00%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e100.00%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRight axis deviation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e90.62%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e91.37%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e91.29%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWide QRS-T angle/ strain\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e9.38%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e99.64%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e90.32%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003eEbstein\u0026rsquo;s anomaly\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTall P wave\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e28.57%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e99.28%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e97.54%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eProlonged PR interval\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e100.00%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e98.20%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e98.25%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRight bundle branch block\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e57.14%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e98.92%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e97.89%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWPW preexcitation/ delta wave\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e28.57%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e99.28%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e97.54%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eDORV with subaortic VSD, no PS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eProlonged PR interval\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e50.00%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e98.20%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e96.85%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLeft axis deviation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e37.50%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e97.84%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e96.15%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCounterclockwise depolarization\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e50.00%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e92.81%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e91.61%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eDORV, subaortic VSD, severe PS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eProlonged PR interval\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e52.63%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e98.20%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e95.29%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eVertical/ right QRS axis\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e89.47%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e79.50%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e80.13%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCounterclockwise depolarization\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e57.89%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e92.81%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e90.57%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eDORV, subpulmonary VSD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eProlonged PR interval\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.00%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e98.20%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e96.47%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eVertical/ right QRS axis\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e80.00%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e79.50%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e79.51%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eClockwise depolarization\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e80.00%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e94.96%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e94.70%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003eTricuspid atresia\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTall P wave\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e44.44%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e99.28%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e95.95%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLeft axis deviation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e83.33%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e97.84%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e96.96%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCounterclockwise depolariation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e77.78%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e92.81%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e91.89%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLeft ventricular hypertrophy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e22.22%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e96.76%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e92.23%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eSingle ventricle physiology with morphologic left ventricle, non-inverted outlet chamber\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLeft axis deviation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e100.00%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e97.84%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e97.86%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDominant R in V\u003csub\u003e1\u003c/sub\u003e and equidiphasic RS in midprecordial leads\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e100.00%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e100.00%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e100.00%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSingle ventricle physiology with morphologic left ventricle, inverted outlet chamber\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eQRS axis inferior and to right\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e80.00%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e79.50%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e79.51%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eSingle ventricle physiology with morphologic right ventricle\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRight axis deviation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e75.00%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e86.69%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e86.52%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTall stereotyped precordial R wave\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e75.00%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e100.00%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e99.65%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSingle ventricle with increased pulmonary blood flow\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLeft atrial/ biatrial enlargement (bifid P or tall bifid P)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e50.00%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e98.92%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e98.23%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSingle ventricle with decreased pulmonary blood flow\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRight atrial enlargement (tall P wave)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e14.29%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e99.28%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e97.19%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003eECG: electrocardiogram; CHD: congenital heart disease; ASD: atrial septal defect; VSD: ventricular septal defect; PDA: patent ductus arteriosus; AS: aortic stenosis; CoA: coarctation of aorta; WPW: Wolff-Parkinson-White; DORV: double outlet right ventricle; PS: pulmonary stenosis\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eTwo research questions formed basis of this study: how prevalent actually are the typical ECG features in congenital heart diseases, and, can ECG be used for screening of CHD?\u003c/p\u003e \u003cp\u003eWe found diverse prevalence of the established ECG features in CHDs. There is variation in terms of ECG features in different CHDs, as well as variation in prevalence of different parameters in the same CHD. For example, both ECG features (right axis deviation, tall monophasic R in V1 with early transition to rS in V2) of tetralogy of Fallot has been noticed with 100% prevalence. On the other hand, well described ECG feature of leftward P axis in sinus venosus ASD had a prevalence of only 11.1%.\u003c/p\u003e \u003cp\u003eWhile studying the prevalence of these known disease-associated ECG features in population with structurally normal heart (no congenital heart disease, and no acquired heart disease), there was commendable presence of a few of these. For example, absence of Q wave in left precordial leads, a feature of congenitally corrected transposition of great arteries (CCTGA), was found in 35.3% of normal population. On statistical analysis of the study, however, most of the ECG parameters in most of heart diseases had a good specificity and accuracy in detection.\u003c/p\u003e \u003cp\u003eSome of the features that did not have high specificity (like right axis deviation in tetralogy of Fallot, absence of Q wave in left precordial leads in CCTGA), had excellent sensitivity, with the prospect of aiding in diagnosis.\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eOstium secundum ASD:\u003c/h2\u003e \u003cp\u003eAbsence of sinus arrhythmia was the most consistent feature in our study. Presence of rSR\u0026rsquo; in right precordial leads and crochetage pattern in at least 1 inferior lead was found more commonly than that described by researchers earlier.\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e,\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e Furthermore, absence of sinus arrhythmia was a highly sensitive and specific parameter to diagnose hemodynamically significant OSASD, with highest accuracy of all the ECG features. Crochetage pattern in all inferior leads was the most specific (100%) one, and though it has been noted to have a poor sensitivity (11.58%) and the lowest accuracy (77.48%) of all, the accuracy stands well. On the other hand, crochetage pattern in at least 1 lead had a high specificity (99.64%) and commendable accuracy (87.94%). Both rsR\u0026rsquo; in right precordial leads and PR prolongation had good specificity and accuracy as well. We also found left axis deviation in 1 patient without any syndromic association; this is likely to represent acquired left anterior fascicular block.\u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eHence, absence of sinus arrhythmia along with rSR\u0026rsquo; pattern in right precordial leads and crochetage in at least one lead can be well used for screening of hemodynamically significant OSASD by ECG, with good accuracy in detection, and a highly specific crochetage in all inferior leads will aid in ruling in the diagnosis.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eSinus venosus ASD\u003c/h3\u003e\n\u003cp\u003eOnly ECG parameter described as hallmark of sinus venosus ASD (SVASD) in literature, leftward P axis, was seen only in 11.1% of patients, compared to 46% reported by Davia et al.\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e This parameter turned out to be specific and accurate, but poorly sensitive. Therefore, absence of leftward P axis (or presence of normal P axis) cannot be used to rule out SVASD in a patient with clinical features suggestive of a pre-tricuspid shunt. On the contrary, presence of this feature will act in favour of diagnosis of SVASD.\u003c/p\u003e \u003cp\u003eWe also detected leftward P axis in a patient with secundum ASD without any related syndromic association, making use of P axis as a sole marker for type of ASD even less reliable.\u003c/p\u003e\n\u003ch3\u003eAtrioventricular septal defect\u003c/h3\u003e\n\u003cp\u003eMost consistent feature was prolonged PR interval, with a prevalence of 73.9% as compared to 50% described by Jacobsen et al.\u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e As per prevalence, this was followed by extreme left axis deviation (65.2%, mostly seen in association of Down syndrome in our study group) and counterclockwise depolarization (34.8%). PR prolongation also had highest sensitivity (73.91%) of all; extreme left axis deviation was most specific (100.00%) and accurate (97.34%). Good accuracy was observed in other parameters: left axis deviation (97.02%), PR prolongation (96.35%) and counterclockwise depolarization (88.37%). All the parameters had good specificity as well.\u003c/p\u003e \u003cp\u003eHence constellation of these features can be effectively used to screen for presence of atrioventricular septal defect, including ostium primum ASD, with good accuracy. Presence of phenotypic features of Down syndrome should also be taken in consideration.\u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003ePost-tricuspid shunt (VSD/ PDA):\u003c/h2\u003e \u003cp\u003eMost prevalent ECG feature was large equiphasic RS waves in midprecordial leads (Katz-Wachtel phenomenon), found in 86.4% patients in our study, as compared to 97.1% described by Sarmila et al.\u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e Katz-Wachtel phenomenon also had the highest sensitivity (86.41%) of all, with excellent specificity (100%) and accuracy (96.33%). Sensitivity of other parameters was not so good, but all of them had high specificity; specificity of signs of LVVO, signs of left atrial enlargement and signs of biatrial enlargement being 93.53%, 98.92% and 99.28% respectively. Signs of LVVO including Q wave in V\u003csub\u003e5\u003c/sub\u003e/V\u003csub\u003e6\u003c/sub\u003e had a commendable accuracy of 86.09%, whereas that of left atrial enlargement was 83.46%.\u003c/p\u003e \u003cp\u003eThereafter, presence of large equiphasic RS waves in midprecordial leads can be used as a screening tool for detection of hemodynamically significant post-tricuspid shunts. Simultaneous presence of signs of LVVO including Q wave in lead V\u003csub\u003e5\u003c/sub\u003e/V\u003csub\u003e6\u003c/sub\u003e and signs of left atrial enlargement, if found, will ascertain the diagnosis more.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eLVOT obstruction (severe AS/ severe CoA):\u003c/h2\u003e \u003cp\u003eShah et al reported ECG evidence of left ventricular hypertrophy (LVH) in 29.4% and LV strain pattern in 20.6% patients.\u003csup\u003e8\u003c/sup\u003e Though we found LVH with a greater prevalence (41.2%), prevalence of LV strain is lower in our study (11.7%). Both LVH and LV strain turned out to have low sensitivity. On the contrary they had excellent specificity, specificity of LVH being 96.76% and that of LV strain being 99.64%. Both had good accuracy; signs of LVH 93.56% accurate and LV strain 94.58% accurate.\u003c/p\u003e \u003cp\u003eHence, presence of LVH with or without LV strain pattern in 12 lead ECG will be helpful in narrowing down diagnosis towards significant LVOT obstruction with good accuracy. But absence of these cannot be used to rule out these heart defects.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eTetralogy of Fallot (TOF):\u003c/h2\u003e \u003cp\u003eOf all the CHDs included in our study, TOF was most consistent with established ECG features, with 100% patients showing monophasic R in V1 with early transition in V2, and right axis deviation. This is also at par with the result of a previous study that described right axis deviation in 96%.\u003csup\u003e9\u003c/sup\u003e However right axis deviation was also noted in ECG of 13.3% patients with structurally normal heart, despite taking in account age-related changes in ECG axis during evaluation. No particular cause of this could be assigned. Both the ECG parameters were 100% sensitive in detection of TOF. While specificity of early transition was 100%, specificity of right axis deviation was lower (86.69%).\u003c/p\u003e \u003cp\u003eHence, in a cyanotic patient, presence of these two findings on ECG can be safely used to make a provisional diagnosis of classic tetralogy of Fallot.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eCongenitally corrected transposition of great arteries (CCTGA):\u003c/h2\u003e \u003cp\u003eAbsence of Q wave in left precordial leads (LPL) was seen in 100% patients, but simultaneous presence of Q in right leads (RPL) was in only one-third (36.4%). One study reported both of these in 100% patients.\u003csup\u003e10\u003c/sup\u003e Absence of Q wave in LPL, though was 100% sensitive according to our study, had a lower specificity. On the contrary, presence of Q wave in RPL had a poor sensitivity (36.36%) but an excellent specificity (99.28%). Three other ECG parameters also had good specificity: upright T wave in all precordial leads (99.64%), complete heart block (99.28%) and any degree of atrioventricular block (97.12%). All the parameters were highly accurate except absence of Q wave in LPL.\u003c/p\u003e \u003cp\u003eHence absence of Q wave in LPL (sensitive) along with one or more of the other specific and accurate parameters can be used safely for detection of CCTG; a point to highlight here would be the need of combining at least one of the specific features with the sensitive parameter.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003eSevere pulmonary stenosis (intact ventricular septum):\u003c/h2\u003e \u003cp\u003e We noted tall monophasic R/qR in V1 lead in 100% of the patients, followed closely by right axis deviation in 90.6% patients. Bassingthwaighte et al reported presence of tall monophasic R wave in V1 in 80%.\u003csup\u003e12\u003c/sup\u003e The 3 patients in our study who did not have right axis deviation in frontal leads had left axis deviation, and all of them had Noonan syndrome, keeping at par with known feature of the syndrome. We also found ECG estimated gradient of RVOT (voltage of R wave in lead V1 in mm multiplied by 15, expressed in mm Hg) coinciding with doppler derived gradient in 84.4% patients.\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eAfter analysis, tall monophasic R/qR in V1 lead was 100% sensitive, specific and accurate in our study. While right axis deviation had commendable sensitivity (90.62%) and specificity (91.37%), tall peaked P wave and wide QRS-T angle/ strain pattern had excellent specificity but poor sensitivity. Accuracy of these three features was good (\u0026gt;\u0026thinsp;90%).\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eHowever, the two highly sensitive and specific features, namely right axis deviation and tall monophasic R/qR in V1 are suggestive of right ventricular hypertrophy, and RVH is not exclusive to this group of CHD. Hence, simultaneous presence of any or both of the other two specific and accurate (but not very sensitive) parameters, tall peaked P wave and wide QRS-T angle/strain, along with any/both features of RVH, can be used to detect severe PS/intact ventricular septum with confidence, in an acyanotic patient. The ECG estimated gradient can also be used by physicians to anticipate RVOT gradient.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003eEbstein\u0026rsquo;s anomaly:\u003c/h2\u003e \u003cp\u003e100% patients in our study had prolonged PR interval, compared to Assenza et al who found it in 17% of the patients.\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e We found this to be highly sensitive (100%), specific (98.20%) and accurate (98.25%). Other three parameters (tall P wave, right bundle branch block, WPW preexcitation/ delta wave) though had low sensitivity, had very good specificity (\u0026ge;\u0026thinsp;99%) and accuracy (\u0026gt;\u0026thinsp;97%). Right bundle branch block pattern and WPW pre-excitation pattern were mutually exclusive.\u003c/p\u003e \u003cp\u003eTherefore, prolonged PR interval and tall P wave, along with either RBBB or WPW pre-excitation pattern, can be very well used as a screening tool to detect Ebstein anomaly, with additional emphasis by with clinical features like multiple heart sounds.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003eDORV with subaortic VSD and no PS (DORV, VSD type):\u003c/h2\u003e \u003cp\u003eWe found higher prevalence of prolonged PR interval (50%), in comparison to Krongrad et al (26%).\u003csup\u003e14\u003c/sup\u003e All 3 ECG parameters (prolonged PR interval, left axis deviation and counterclockwise depolarization) in diagnosis of DORV/subaortic VSD/no PS had good specificity and accuracy (\u0026gt;\u0026thinsp;90%) but poor sensitivity (\u0026lt;\u0026thinsp;50%).\u003c/p\u003e \u003cp\u003eHence, these features can be used as a screening tool to rule in DORV/VSD type, but absence of these will not help to rule out the disease.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec18\" class=\"Section2\"\u003e \u003ch2\u003eDORV with subaortic VSD and PS (DORV, TOF type):\u003c/h2\u003e \u003cp\u003eIn this group too we found higher prevalence of prolonged PR interval (52.6%), in comparison to Krongrad et al (26%).\u003csup\u003e14\u003c/sup\u003e The parameter with highest sensitivity was vertical/right QRS axis (sensitivity 89.47%) but it had lower specificity and accuracy. On the other hand, prolonged PR interval and counterclockwise depolarization had good specificity and accuracy, with low sensitivity.\u003c/p\u003e \u003cp\u003eThereafter, constellation of sensitive vertical/right QRS axis and any or both of the other two specific features can be safely used to detect DORV/subaortic VSD/PS by ECG screening, in a cyanotic patient.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec19\" class=\"Section2\"\u003e \u003ch2\u003eDORV with subpulmonary VSD (DORV, TGA type, Taussig-Bing anomaly):\u003c/h2\u003e \u003cp\u003eAs prolonged PR interval had zero sensitivity in this group, it cannot be used as a screening parameter. Clockwise depolarization had good specificity and accuracy (94% or more), but lower sensitivity (80%). Vertical/right QRS axis had moderate sensitivity and specificity (near 80%).\u003c/p\u003e \u003cp\u003eHence, in the absence of a highly sensitive ECG parameter, clockwise depolarization and vertical/QRS axis can be used together to rule in DORV/ subpulmonary VSD in a relevant clinical background (cyanosis, increased pulmonary blood flow), but absence of these cannot be safely used to rule out this.\u003c/p\u003e \u003cp\u003eFinally, taking in account all variants of double outlet right ventricle, our study shows that PR prolongation along with subgroup-specific pattern of QRS axis and limb lead depolarization can aid in screening of this cohort of CHD, though these is lack of literature looking into prevalence pattern of these.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec20\" class=\"Section2\"\u003e \u003ch2\u003eTricuspid atresia:\u003c/h2\u003e \u003cp\u003eHallmark features in ECG like left axis deviation and counterclockwise depolarization were found in 83.3% and 77.8% patients respectively. Tall P wave and left ventricular hypertrophy was even less prevalent. We did not find any previous study to compare. All the ECG parameters showed excellent (90% or more) specificity and accuracy, but only moderate sensitivity. Most sensitive of these was left axis deviation (83.33%), followed by counterclockwise depolarization (77.78%). Tall P wave had highest specificity (99.28%) and left axis deviation was most accurate (96.96%).\u003c/p\u003e \u003cp\u003eConstellation of sensitive features like left axis deviation and counterclockwise depolarization in limb leads in a patient of cyanotic congenital heart disease, along with one or more other specific features like tall P wave and LVH, if found, can be used to rule in tricuspid atresia. However, absence of only poorly sensitive tall P wave and LVH cannot be used to rule out tricuspid atresia.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec21\" class=\"Section2\"\u003e \u003ch2\u003eSingle ventricle:\u003c/h2\u003e \u003cp\u003eThis group of congenital heart diseases have the maximum variety of subgroups according to anatomical and hemodynamic variations, with each subgroup described to have some pathognomonic ECG findings. To our knowledge, this is the first study on prevalence of ECG patterns in this group of CHDs. When sub-grouped as anatomical variations (morphological RV vs LV or inverted vs non-inverted outlet chamber), the established ECG features had quite high prevalence; for example, left axis deviation in morphological LV with non-inverted outlet chamber (100%) and inferior/ rightward QRS axis in morphological LV with inverted outlet chamber (80%).\u003c/p\u003e \u003cp\u003eIn evaluation of single ventricle physiology with morphologic left ventricle and non-inverted outlet chamber, both left axis deviation and dominant R in V\u003csub\u003e1\u003c/sub\u003e and equidiphasic RS in midprecordial leads were highly sensitive and specific (\u0026ge;\u0026thinsp;97%). In evaluation of single ventricle physiology with morphologic left ventricle and inverted outlet chamber, the established ECG parameter of inferior and rightward QRS axis had moderate sensitivity and specificity (around 80%). In evaluation of single ventricle physiology with morphologic right ventricle, tall stereotyped precordial wave was 100% specific, and right axis deviation 86.69% specific. Both had lower sensitivity of 75%.\u003c/p\u003e \u003cp\u003eHowever, atrial enlargement pattern according to pulmonary blood flow (left atrial enlargement in increased pulmonary blood flow or right atrial enlargement in decreased pulmonary blood flow) was seen with less prevalence, poor sensitivity, but good specificity. Hence, it will be difficult to use these features only to rule out the CHD, but if it is present in a patient with other ECG features of single ventricle, it can be used to comment on increased or decreased pulmonary blood flow.\u003c/p\u003e \u003cp\u003eAfter considering all, our analysis remains: constellation of features can be safely used to comment on anatomical/ morphological type of univentricular CHD, though the same will be less applicable to screen pattern of pulmonary blood flow. If clinical features of increased or decreased pulmonary blood flow is taken in account along with chest x-ray (pulmonary oligemia vs plethora), ECG will be more helpful to raise alarm about suspicion of this group of congenital heart disease. Relatively small sample size in this group also precludes a strong comment.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec22\" class=\"Section2\"\u003e \u003ch2\u003eFormulating differential diagnoses from ECG:\u003c/h2\u003e \u003cp\u003eFurther, we realise that isolated ECG features can be common to more than one heart defect, for example prolonged PR interval. How would then we know what disease the patient has by looking at ECG strip? Here, we formulate a different approach. If considered individually, or if found in the absence of conglomeration of disease-specific features, the ECG findings can still be useful to establish a list of differential diagnoses, and thereafter to narrow down the diagnosis taking help of supporting clinical findings (Table \u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDifferential diagnosis of abnormal ECG feature (the ones found in multiple CHDs)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDifferential diagnosis: prolonged PR interval\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDifferential diagnosis: left axis deviation\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDifferential diagnosis: right axis deviation (including vertical/right QRS axis)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eDifferential diagnosis: left atrial enlargement\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eDifferential diagnosis: right atrial enlargement\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1. Hemodynamically significant OSASD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1. Atrioventricular septal defect (including ostium primum ASD)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1. Tetralogy of Fallot\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1. Hemodynamically significant (moderate to large) post tricuspid shunt (VSD, PDA)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1. Severe pulmonary stenosis (intact ventricular septum)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2. Atrioventricular septal defect (including ostium primum ASD)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2. DORV/ subaortic VSD/ no PS (DORV, VSD type)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2. Severe pulmonary stenosis/ intact ventricular septum\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2. Single ventricle physiology with increased pulmonary blood flow\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2. Ebstein\u0026rsquo;s anomaly\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3. Ebstein\u0026rsquo;s anomaly\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3. Tricuspid atresia\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3. DORV/ subaortic VSD/ severe PS (DORV, TOF type)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3. Tricuspid atresia\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4. Double outlet right ventricle, all anatomical variants\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4. Single ventricle physiology with morphologic left ventricle and non-inverted outlet chamber\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4. DORV/ subpulmonary VSD (DORV, TGA type, Taussig-Bing anomaly)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4. Single ventricle physiology with decreased pulmonary blood flow\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5. Single ventricle physiology with morphologic right ventricle\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003eECG: electrocardiogram; CHD: congenital heart disease; ASD: atrial septal defect; VSD: ventricular septal defect; PDA: patent ductus arteriosus; AS: aortic stenosis; CoA: coarctation of aorta; WPW: Wolff-Parkinson-White; DORV: double outlet right ventricle; PS: pulmonary stenosis\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eHow we arrive diagnosis from the differential is a systematic approach. PR prolongation is highly specific for the 4 diseases, with \u0026gt;\u0026thinsp;95% specificity and accuracy. Of these DORV/ subaortic VSD/ PS (DORV, TOF type) is cyanotic, and DORV/ subpulmonic VSD (DORV, TGA type) presents with mild cyanosis and features of increased pulmonary blood flow. Other than these two, rest of the CHDs are acyanotic. Thereafter, if PR prolongation (age-specific PR interval to be taken in account) is noticed in ECG with pertinent clinical scenario, keeping in mind the list of differential diagnoses, specific features of CHDs are to be sought for.\u003c/p\u003e \u003cp\u003eLet us look at the list under left axis deviation. Tricuspid atresia and the variant of single ventricle with decreased pulmonary blood flow will have cyanosis. On the contrary, AVSD and DORV/VSD type and single ventricle with increased pulmonary blood flow will present with signs and symptoms of increased pulmonary blood flow. Extreme left axis is again 100% specific for AVSD. Hence, combining left axis deviation with other specific ECG features of each CHD, and clinical signs, physicians will be able put a finger on diagnosis, even in the absence of immediate echocardiography.\u003c/p\u003e \u003cp\u003eRight axis deviation has more specificity in TOF and severe PS/ intact ventricular septum as compared to rest three. Classic TOF and DORV/subaortic VSD/ PS both are cyanotic heart diseases with similar clinical presentation. Associated ECG features of respective CHDs along with right axis deviation in a cyanotic patient therefore not only can diagnose TOF physiology but also differentiate between these two. Early transition pattern favours diagnosis of TOF, whereas counterclockwise depolarization and prolonged PR interval are in favour of DORV/VSD/PS. Persistence of counterclockwise depolarization in the form of q wave in lead I and aVL even when the QRS axis is vertical/ rightward is a distinctive feature of DORV/VSD/PS whereas q in lead I and aVL is virtually unheard of in classic TOF. Single ventricle with morphological RV and decreased pulmonary blood flow will also have cyanosis, and tall stereotyped precordial R wave is a pointer towards this. DORV/subpulmonic VSD (DORV, TGA type) will have mild cyanosis with features of increased pulmonary blood flow, and associated clockwise depolarization. An important differential of this group in severe PS/intact ventricular septum, suspicion about which wil be raised by simultaneous presence of tall P wave, monophasic R/qR pattern in V1 (with no early transition pattern), and wide QRS/T angle or strain pattern.\u003c/p\u003e \u003cp\u003eBoth the CHDs, for which bifid and wide P wave (P mitrale), suggestive of left atrial enlargement, has been found to be specific (though not so sensitive), present with features of increased pulmonary blood flow. Clinical findings of murmur would act as a first pointer towards post tricuspid shunt. Presence of other specific ECG features will help as well. For example, large equiphasic RS in midprecordial leads (Katz-Wachtel phenomenon) and sign of left ventricular volume overload, if found, helps to rule in post-tricuspid shunt. On the other hand, depending on the morphological type of single ventricle and anatomical variant, specific ECG features will aid in diagnosis. Left axis deviation and dominant R in V1 and equidiphasic RS in midprecordial leads will point towards single ventricle physiology with morphologic left ventricle, non-inverted outlet chamber. Tall stereotyped precordial R wave will point towards single ventricle physiology with morphologic right ventricle.\u003c/p\u003e \u003cp\u003eFor the CHDs with right atrial enlargement, single ventricle with decreased pulmonary blood flow patients will definitely have some degree of cyanosis, with variable presence of cyanosis in other CHDs. Other associated ECG features will aid to narrow down the diagnosis from this list. For example, severe PS/intact ventricular septum has other specific features like right axis deviation and tall monophasic R/qR in V1. Ebstein\u0026rsquo;s anomaly has specific features like PR prolongation, WPW preexcitation/ delt wave and right bundle branch block pattern (last two are mutually exclusive).\u003c/p\u003e \u003cp\u003eTo summarise, constellation of sensitive and specific features, as described in the discussion section, will aid in detection. Therefore, ECG can be used as a screening tool to prepare a list of possible differential diagnosis, as well as to raise suspicion about presence of a certain CHD. Pertinent clinical scenario, if noted, will further strengthen this screening.\u003c/p\u003e"},{"header":"CONCLUSION AND LIMITATION","content":"\u003cdiv id=\"Sec23\" class=\"Section3\"\u003e\n \u003cp\u003eReflecting back on the research questions, prevalence pattern of established well-known specific electrocardiogram features in common congenital heart diseases has been assessed in this research. Varying prevalence of ECG findings in some CHDs has also been noted. Analysis of study results in terms of sensitivity, specificity and accuracy guides to the conclusion that 12 lead ECG can be used as a screening tool to raise suspicion about presence of certain common congenital heart diseases. Using constellation of features will strengthen this screening purpose more, combining sensitive and specific parameters. Therefore, it can be proposed that constellation of ECG features, along with simple screening tools like pulse oximetry and clinical findings, will aid in screening of suspected congenital heart diseases by primary care physicians and pediatricians, in the outpatient practice. This will further prompt referral to cardiology service, specifically from areas where advanced investigation tools like echocardiography may not be readily available. A faster referral and prompt diagnosis will be of utmost importance considering the burden of congenital heart disease.\u003c/p\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eLimitations of the study\u003c/span\u003e: Limited duration of the study (18 months) and recruitment of only new patients who/ whose parents gave consent leading to limited number of patients in general, and less prevalence of some congenital heart diseases like single ventricle and sinus venosus ASD led to recruitment of a smaller number of patients with these diseases in the study. We encourage further larger multicentre studies with longer duration to establish population prevalence of ECG features, and strengthen the aim of using 12 lead ECG as a screening tool for diagnosis of congenital heart diseases.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003eCompeting interest: None.\u003c/p\u003e\n\u003cp\u003eAcknowledgements: None\u003c/p\u003e\n\u003cp\u003eFunding: This study has received no external funding.\u003c/p\u003e\n\u003cp\u003eDisclosure of interest: None\u003c/p\u003e\n\u003cp\u003eData availability statement: The data used to support the findings of this study are included within the article.\u003c/p\u003e\n"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003ePerloff JK, Marelli A. Perloff\u0026rsquo;s clinical recognition of congenital heart disease: Expert consult - online and print. 6th ed. London, England: W B Saunders; 2012\u003c/li\u003e\n\u003cli\u003eRefaei M, Islam S, Mackie AS, Atallah J. Correlation of electrocardiogram parameters and hemodynamic outcomes in patients with isolated secundum atrial septal defects. Ann Pediatr Cardiol. 2017;10(2):4103 0974\u0026ndash;2069.\u003c/li\u003e\n\u003cli\u003eCohen JS, Patton DJ, Giuffre RM. The crochetage pattern in electrocardiograms of pediatric atrial septal defect patients. Can J Cardiol. 2000;16(10):1241\u0026ndash;7.\u003c/li\u003e\n\u003cli\u003eShen L, Liu J, Li J-K, Xu M, Yuan L, Zhang G-Q, et al. The significance of crochetage on the R wave of an electrocardiogram for the early diagnosis of pediatric secundum atrial septal defect. Pediatr Cardiol. 2018;39(5):1031\u0026ndash;5\u003c/li\u003e\n\u003cli\u003eDavia JE, Cheitlin MD, Bedynek JL. Sinus venosus atrial septal defect: Analysis of fifty cases. Am Heart J. 1973;85(2):177\u0026ndash;85.\u003c/li\u003e\n\u003cli\u003eJacobsen JR, Gillette PC, Corbett BN, Rabinovitch M, McNamara DG. Intracardiac electrography in endocardial cushion defects. Circulation. 1976;54(4):599\u0026ndash;603.\u003c/li\u003e\n\u003cli\u003eSarmila B, Iskandar B, Daud D. Diagnostic value of electrocardiography for ventricular septal defect. Paediatr Indones. 2019;59(2):87\u0026ndash;91.\u003c/li\u003e\n\u003cli\u003eShah AS, Chin CW, Vassiliou V, Cowell SJ, Doris M, Kwok TC, et al. Left ventricular hypertrophy with strain and aortic stenosis. Circulation. 2014;130:1607\u0026ndash;1616.\u003c/li\u003e\n\u003cli\u003eRoberts DL, Wagner HR, Lambert EC. The electrocardiogram in tetralogy of Fallot. J Electrocardiol. 1972;5(2):155-61.\u003c/li\u003e\n\u003cli\u003eVictorica BE, Miller BL, Gessner IH. Electrocardiogram and vectorcardiogram in ventricular inversion (corrected transposition. Am Heart J. 1973;86:733\u0026ndash;744.\u003c/li\u003e\n\u003cli\u003eWalker WJ, Cooley DA, Mc ND, Moser RH. Corrected transposition of the great vessels, atrioventricular heart block, and ventricular septal defect: a clinical triad. Circulation. 1958;17:249\u0026ndash;254\u003c/li\u003e\n\u003cli\u003eBassingthwaighte JB, Parkin TW, Dushane JW, Wood EH, Burchell HB. The electrocardiographic and hemodynamic findings in pulmonary stenosis with intact ventricular septum. Circulation. 1963;28: 893\u0026ndash;905. \u003c/li\u003e\n\u003cli\u003eAssenza GE, Valente AM, Geva T, Graham D, Pluchinotta FR, Sanders SP, et al. \u0026ldquo;QRS duration and QRS fractionation on surface electrocardiogram are markers of right ventricular dysfunction and atrialization in patients with Ebstein anomaly\u0026rdquo; [Eur Heart J 2012;34:191-200, doi:10.1093/eurheartj/ehs362]. Eur Heart J. 2013;34(8):624\u0026ndash;624.\u003c/li\u003e\n\u003cli\u003eKrongrad E, Ritter DG, Weidman WH, Dushane JW. Hemodynamic and anatomic correlation of electrocardiogram in doubleoutlet right ventricle. Circulation. 1972;46:995\u0026ndash; 1004.\u003c/li\u003e\n\u003cli\u003eHarrison DC, Morrow AG. Electrocardiographic evidence of left axis deviation in patients with defects of the atrial septum of the secundum type. N Engl J Med. 1963;269:743\u0026ndash;745.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"12 lead ECG, congenital heart disease, accuracy of ECG, prevalence of ECG","lastPublishedDoi":"10.21203/rs.3.rs-6106927/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6106927/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground and aims:\u003c/h2\u003e \u003cp\u003eCongenital heart diseases (CHD) account for a major portion of congenital anomalies. Certain electrocardiogram (ECG) features have been described as pathognomonic for some CHDs, over years. If ECG can be used as a screening tool, it would prompt detection of CHDs in resource-limited areas. However, comprehensive research on ECG's diagnostic accuracy is required before embarking on such a venture.\u003c/p\u003e\u003ch2\u003eMethods:\u003c/h2\u003e \u003cp\u003eThis study, conducted in a tertiary care centre of Eastern India, aims to find out actual percentage prevalence of classical ECG features in different CHDs, and therefore, to assess diagnostic accuracy of the said ECG pointers (Fig.\u0026nbsp;1: graphical abstract).\u003c/p\u003e\u003ch2\u003eResults:\u003c/h2\u003e \u003cp\u003eSignificant variation in ECG findings was noted across different CHDs; some like right axis deviation in TOF showed 100% prevalence and sensitivity, while others, like leftward P axis in sinus venosus ASD, were much less common. Many ECG features were highly specific, such as 100% specific Katz-Wachtel phenomenon in post-tricuspid shunts. Also, high diagnostic accuracy of ECG was demonstrated across several CHDs; 100% accuracy for tall monophasic R in V1 in severe PS, and high accuracy (\u0026gt;\u0026thinsp;95%) for PR prolongation and extreme axis deviations in AVSD and Ebstein\u0026rsquo;s anomaly. Overall, ECG parameters had high specificity and accuracy but varied in sensitivity, with combinations of specific and sensitive features proving effective for diagnosis in specific CHDs.\u003c/p\u003e\u003ch2\u003eConclusions:\u003c/h2\u003e \u003cp\u003eA combination of specific ECG features, along with simple clinical tools can effectively screen for common CHDs, guiding early referral to cardiology service, especially in areas with limited access to advanced diagnostic tools like echocardiography.\u003c/p\u003e","manuscriptTitle":"Role of electrocardiogram in detecting congenital heart disease:prevalence and diagnostic accuracy of pathognomonic features","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-03-26 15:19:46","doi":"10.21203/rs.3.rs-6106927/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-04-18T17:09:48+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-04-17T20:38:57+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-04-12T02:00:50+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"211461760991663906645316185499454189801","date":"2025-04-05T09:51:40+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"170503973477529356322505001760516897130","date":"2025-04-05T05:28:55+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-03-25T04:47:37+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-03-25T04:40:29+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-03-18T05:16:23+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-03-17T04:58:10+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2025-02-25T16:09:45+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"4417e354-2773-45da-afdf-37fc8e65f78b","owner":[],"postedDate":"March 26th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":46252729,"name":"Health sciences/Diseases/Cardiovascular diseases/Congenital heart defects"},{"id":46252730,"name":"Health sciences/Cardiology"},{"id":46252731,"name":"Health sciences/Cardiology/Cardiovascular biology/Cardiovascular diseases/Congenital heart defects"}],"tags":[],"updatedAt":"2025-12-22T10:53:49+00:00","versionOfRecord":[],"versionCreatedAt":"2025-03-26 15:19:46","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6106927","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6106927","identity":"rs-6106927","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}