Feasibility of a Göttingen mini-pig mini-invasive model for myocardial infarction induction

Feasibility of a Göttingen mini-pig mini-invasive model for myocardial infarction induction | 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 Research Article Feasibility of a Göttingen mini-pig mini-invasive model for myocardial infarction induction Noé Corpataux, Maria Francesca Petrucci, Fabien Praz, Anselm W. Stark, and 8 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7373600/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Myocardial infarction (MI) remains a major research focus, with efforts aimed at preserving myocardial cells and reducing fibrosis. Survival animal models are crucial for studying MI but present challenges due to disease severity and potential animal suffering. In this study, ischemia was induced in 12 Göttingen mini-pigs using transcatheter balloon occlusion of the left anterior descending artery, followed by 90 minutes of ischemia and 2 hours of reperfusion. Transthoracic echocardiography and MRI were performed before and after MI using dedicated imaging protocols. Three animals (25%) experienced ventricular fibrillation; two were successfully resuscitated, while one died. Significant post-infarction changes were observed, with a mean ejection fraction of 43% and myocardial fibrosis of 15.5%. In the subset of animals that didn’t experienced ventricular fibrillation, fibrosis increased by 10.25 ± 5.4%, while ejection fraction declined from 54 ± 3.8% to 43.3 ± 3.56% (p < 0.01). These findings suggest that this minimally invasive model is a viable approach for MI research, although the risk of lethal arrhythmias remains a concern in cases of large infarcts. Myocardial infarction induction Minimally invasive model Göttingen mini-pig Cardiac magnetic resonance imaging (CMR) Translational cardiology Fibrosis quantification Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Introduction Myocardial infarction (MI) is a critical cardiovascular emergency characterized by the abrupt loss of cardiomyocytes and subsequent myocardial remodeling. This pathological process frequently results in the formation of collagen-based scar tissue [ 1 , 2 ], which compromises myocardial function and predisposes patients to heart failure with reduced ejection fraction (HFrEF). HFrEF remains a significant global health burden, marked by debilitating symptoms, poor quality of life, and high mortality rates [ 3 ]. Effective therapeutic interventions for MI and its sequelae rely heavily on preclinical investigations on animal models that closely replicate the human pathophysiology of ischemic heart disease. Murine models have traditionally been employed to investigate MI, owing to their genetic tractability and cost-effectiveness [ 4 , 5 ]. However, the inherent structural and functional disparities between rodent and human hearts limit their translational applicability. In particular, murine hearts exhibit a much higher heart rate, smaller size, and distinct myocardial composition compared to humans [ 6 ]. These differences can hinder the clinical relevance of findings, especially when studying myocardial remodeling, fibrosis, and therapeutic interventions. As a result, the demand for larger animal models better approximating human cardiac physiology is increasing. Porcine models, particularly Göttingen mini-pigs, are considered an attractive alternative to rodents for preclinical cardiovascular research. Their cardiac anatomy, size, and functional parameters closely resemble those of humans, making them well suited for translational studies [ 7 – 9 ]. The body size and weight of minipigs are of advantage for advanced imaging modalities, such as cardiac magnetic resonance imaging (MRI) and transthoracic echocardiography (TTE), which provides an unparalleled opportunity for detailed assessment of cardiac function, volume, and tissue characterization. MRI is the gold standard for evaluating myocardial fibrosis and left ventricular remodeling post-MI [ 10 ], enabling high-resolution, clinically relevant analyses helping to bridge the gap between animal studies and human applications. Rationale The goal of this report is to describe the feasibility, viability, and translational value of a Göttingen mini-pig model used for mini-invasive MI induction. We describe the outcomes of the control arm of a randomized control trial investigating new therapeutic approaches for the chronic treatment of ischemic heart disease. Myocardial ischemia was induced occluding the left anterior descending artery to replicate the pathophysiological cascade of human MI and was followed by successful myocardial reperfusion. Echocardiographic protocols adapted to the anatomical features of the mini-pig heart, were used to assess the cardiac damage overt time and its consequences on heart function while biomarkers were measured to quantify the cardiac damage. Advanced imaging techniques, including cine MRI and late gadolinium enhancement (LGE), were integrated to ensure precise characterization of infarct size, myocardial remodeling, and fibrosis. Methods This study was conducted in accordance with the legislation of the Swiss Federal Food Safety and Veterinary Office. The experimental protocol was reviewed and approved by the Cantonal Committee for Animal Experiments of Bern, Switzerland (authorization number: 33492). All methods were carried out in compliance with the relevant institutional and national guidelines for animal research [ 11 – 13 ], and the reporting of methods and results adheres to the ARRIVE guidelines. Animal cohort Twelve adult female and male minipigs (5 females, 7 males; age 12–18 months; weight 27.3 ± 4.1 kg) were purchased from their official breeder Ellegaard Göttingen Minipigs (Dalmose, Denmark), a specific-pathogen-free herd. At least 2 weeks before the start of the trial, the animals were transported to Switzerland, where they were hosted in groups of six to ten in an 18m² pen with a 50m² outdoor area, located on a farm. Water was available ad libitum, and food (Minipigs Maintenance Standard, Kliba Nafag, Switzerland) was provided twice per day (800 grams/minipig/day)[ 12 ]. Physiological and behavioral evaluations were carried out at least three time per week before the beginning of the trial. Further details on animals and housing conditions have been previously published [ 14 ]. At least 24 hours before MI induction, minipigs were transported in groups of two from the hosting farm to the Experimental Surgery Facility (ESF) of the University of Bern. There, they were hosted together in the large animal intensive care unit in a box (length: 2.07 x width: 1.68 x height: 2.50 square meters) Before anaesthesia, minipigs were fasted for 8–12 hours while water remained available ad libitum. Pigs were recovered from general anaesthesia after the procedures in the same boxes wherthey were monitored for at least 15 hours after reaching sternal recumbency. The animals were transported back to the farm only when deemed hemodynamically stable and pain-free. Minipigs were kept at the farm until the study endpoint. Veterinary checks were carried out daily from post-operative (PO) day 1 to PO day 7, and from PO day 8 to PO day 45 at least three times per week. Body weight was checked daily until PO day 3, and then once per week until the study endpoint. On the study endpoint, the minipigs were transported from the farm to the ESF where they were anaesthetised to undergo cardiac magnetic resonance imaging (MRI). Following preanesthetic clinical examination and premedication, they were transported to the TIC-SITEM of the University of Bernn, where preparation for general anaesthesia was accomplished and the scan was carried out. At the end of the diagnostic procedure, minipigs were euthanized under general anaesthesia with an intravenous overdose of pentobarbital (100 mg/kg). Figure 1 presents the experimental protocol as a graphical timeline. Transthoracic echocardiography Transthoracic echocardiogram (TTE) at baseline and 35 to 45 days after iatrogenic myocardial infarction was performed under sedation. Minipigs were injected with IM midazolam 1 mg/kg and ketamine 2 mg/kg during the procedure, oxygen was continuously administered through a face mask (6 L/min) and monitoring consisted of a pulse-oximeter (SpO 2 and pulse rate and width) placed on the ear and electrocardiogram (ECG). In case of insufficient sedation, further 0.2 mg/kg midazolam was injected IM. The images were acquired using a ACUSON SC2000 PRIME ultrasound system (Siemens Healthcare GmbH, Eschborn, Germany) equipped with a 5V1 probe. For the recording of the various echocardiographic views, the mini-pigs had to lie in right lateral recumbency, on a dedicated examination table according to the anatomical location of their heart. Due to the absence of a specific echocardiographic protocol for the evaluation of mini-pigs, we adapted the ASE guidelines [ 15 , 16 ] according to their specific anatomy, to perform a comprehensive echocardiogram. The lines density and the image depth were adapted to obtain a time resolution of at least 50fps in B-Mode and 20fps in color-Doppler mode. The highest frequency providing an adequate penetration of the ultrasounds was utilized to optimize the spatial resolution. The sweep speed for all spectral Doppler recordings was set to 75–100 mm/s. At the beginning of the examination, the pigs were gently positioned on their left side, allowing access to the parasternal right echographic windows at the level of the right anterior limb. The views acquired in this position were the parasternal long-axis (PLAX) and multiples parasternal short-axis (SAX) views. The PLAX view (Fig. 2 ) provided a longitudinal section of the heart, allowing assessment of the left ventricle (LV, posterior and antero-septal walls), mitral valve, and aortic valve. The cross-sectional SAX views were used to assess wall motion abnormalities in all the LV segments. Afterward the pigs were gently turned on their right side for acquisition of a two chambers (2CV) view. The LV volumes and LV ejection fraction were calculated using the Simpson's method of discs after tracing the LV endocardial borders at the end of the diastole and of the systole in 4CV and 2CV. Flumazenil 0.01–0.02 mg/kg (Flumazenil 0.5 mg/5 ml, Labatec Pharma) IM was administered at the end of the procedure if no signs of recovery were present within 60 minutes after injection of sedative drugs. Cardiac MRI examination Cardiac MRI scans were conducted 42 ± 3 days days post-infarction under general anesthesia as described in the supplemental material S1 using a 3T scanner (Prisma, Siemens, Erlangen, Germany) in all animals. A baseline cardiac MRI was performed in 4 subjects during our early experience Cine steady-state free precession (SSFP) images were acquired to assess left ventricular (LV) function and LV mass. The cine imaging was performed in 10–12 short-axis planes (TE = 1.35 ms; 8 mm thick with no gap, in-plane spatial resolution, 1.3 × 1.3 mm) and 3 radial long-axis planes. To discern areas of fibrosis, a supplementary late gadolinium enhancement (LGE) imaging protocol was used. This involved a segmented inversion-recovery pulse sequence, initiated 10 to 15 minutes after injecting 7.5 ml of gadolinium diethylenetriamine pentaacetic acid (Magnevist, Bayer HealthCare Pharmaceuticals Inc., Wayne, New Jersey). The LGE protocol allowed for enhanced visualization and quantification of myocardial scarring, particularly in the subendocardial region of the left anterior descending artery (LAD) flow area. The details of anaesthesia for MRI are reported in the supplemental material. Induction of myocardial infarction Myocardial infarction was induced in general anaesthesia. Briefly, minipigs were sedated with IM injection of 0.2 mg/kg morphine 10 mg/kg ketamine and 15 mcg/kg dexmedetomine mixed in the same syringeIf sedation was deemed inadequate 15 minutes after injection, 0.2 mg/kg midazolam was injected IM. General anaesthesia was induced with intravenous ketamine 1 mg/kg and propofol 1–3 mg/Kg titrated to accomplish tracheal intubation. Following tracheal intubation, the animals were allowed to breath in a spontaneous pressure supported mode, if normocapnia could be maintained. Otherwise volume controlled, pressure limited ventilation was started. Anaesthesia was deepened and maintained with sevoflurane in oxygen and compressed air (60 − 40%). End tidal sevoflurane was adjusted to guarantee adequate depth of anaesthesia up to its MAC (2.7%). Amoxicillin-clavulanic acid 20 mg/kg was administered IV. Lidocaine 30 µg/kg/min (Lidocaine 1%, Streuli Pharma AG) continuous rate infusion (CRI) was infused during the all procedure. Monitoring of HR and rhythm (II lead as basis), respiratory rate, SpO2, capnography, invasive blood pressure, oesophageal temperature, inhaled and exhaled fraction of gases (air, ETCO2), central venous pressure was performed through a multimodal monitor Electroencephalographic activity (EEG) was monitored through surface electrodes positioned on the forehead. Mild hypothermia (35–36◦C) was targeted along the whole intervention and maintained with the help of a forced air device. Before LAD catheterisation, amiodarone 5 mg/kg was administered over 1 hour in CRI. Activated clotting time (ACT) was assessed and a bolus of heparin 80 I.U./kg was administered, followed by CRI (30–80 I.U./kg/h). Heparin rate was adjusted by targeting ACT values of 2–3 times its baseline value after arterial catheter insertion. With the animals positioned in dorsal recumbency, the femoral access was established percutaneously under ultrasound guidance using a modified Seldinger’s technique. A 6 French arterial vascular sheath was then inserted into the femoral artery and sutured in place. Standard catheter shapes designed for human procedures, such as Judkins left and right (JL and JR), were employed to gain selective coronary access. Subsequently, a workhorse coronary wire was engaged in the distal left anterior descending artery (LAD), as shown in Fig. 3 . A visually sized balloon (usually 2.5mm) was introduced and inflated in the midsection of the artery, after the first diagonal branch. In presence of a large intermediate branch, the balloon was inflated proximally to the first diagonal branch. Complete vessel occlusion was confirmed through the injection of contrast medium. The balloon was maintained in place for 90 minutes and then deflated. Two-hours reperfusion in general anaesthesia followed the ischemia. At the end of the procedure, the arterial vascular sheath was extracted, and the puncture site was manually compressed for 5 to 10 minutes. If ventricular fibrillation occurred, cardiopulmonary resuscitation including external defibrillation was carried out based on guidelines for small animals[ 17 ]. Minipigs were declared dead intraoperatively if ventricular fibrillation led to cardiac arrest unresponsive to cardiopulmonary resuscitation and defibrillation (ROSC not achieved within 30 minutes following cardiac arrest). Necropsy Immediately after euthanasia, post-mortem examination and tissue collection was performed by a board-certified veterinary pathologist (SdB). Prior to sampling for histology, the heart was examined for the presence and extent of cardiac infarct and the heart weight was recorded. For histologic analysis, tissue samples were collected from aorta (ascending, arch, descending), heart (atrium right and left, ventricle right and left, septum, infarct zone, infarct border zone, infarct remote zone), spleen, liver, and kidney. The tissues were placed in 10% neutral buffered formalin for a minimum of 48h and then routinely processed and stained with haematoxylin and eosin (HE) for histologic examination. Cardiac tissue sections were additionally stained with Masson Trichrome for the evaluation of fibrosis. Results Twelve Ellegaard Göttingen Minipigs, 5 females and 7 males, aged 15.5 ± 2.1 months and weighing 27.3 ± 4.1 kg underwent MI induction between august 2022 and October 2023. The procedure could be performed successfully mini-invasively with a percutaneous approach in all subjects (100%). Because of ventricular fibrillation with cardiac arrest unresponsive to first defibrillation, the balloon in the mid LAD was temporarily deflated in three pigs (25%). After successful resuscitation and restoration of sinus rhythm, the balloon could be re-inflated in two pigs to achieve the fixed infarction time of 90 minutes. One animal (8%) died during procedure due to refractory ventricular fibrillation. Eleven minipigs were discharged from the Experimental Surgery Facility if in good clinical conditions the day after the procedure and transported back to the farm. Comprehensive cardiac assessments revealed significant post-infarction changes in 9 out of 11 mini-pigs. Among the animals that underwent cardiac MRI at both baseline and follow-up, myocardial fibrosis increased to 10.25 ± 5.4%, while LVEF decreased from 54 ± 3.8% to 43.3 ± 3.56% (p < 0.01). Left ventricular volumes also increased, indicating adverse LV remodeling, with the mean LVEDV rising from 66.55 ± 9.5 ml at baseline to 73.83 ± 12.3 ml post-infarction (p = 0.11). Across the entire cohort, the mean post-infarction LVEF was 42.8 ± 4.3%, and myocardial fibrosis reached 15.5 ± 10.5%, with substantial variability in infarct size and fibrosis percentage among animals, as shown in Fig. 4 . Troponin I levels, measured 13 to 18 hours post-infarction, confirmed myocardial injury with a mean value of 3093 ± 1156 pg/ml. In the two animals where vessel occlusion was interrupted due to refractory ventricular fibrillation, no myocardial fibrosis (LGE/Mass = 0%) or abnormal LVEF (57% and 52%) were observed post-infarction, despite elevated troponin I levels (3567 and 1802 pg/ml). Figure 2 c-d and Fig. 5 illustrate the findings of the post-infarction ultrasound and MRI, revealing myocardium thinning with absence of systolic contraction as well as akinesia and dyskinesia attributable to subendocardial myocardial scarring in the LAD flow area. Necropsy Relevant macroscopic findings were primarily observed in the lungs and heart. Evidence of a white cardiac infarct was observed at the apex, characterized by a focal, variably well-defined, pale and firm myocardial region, indicative of cardiac fibrosis (Fig. 6 A). As previously demonstrated by MRI, the extent of cardiac infarct varied between different heart locations and animals. Upon incision, the affected left ventricular wall was markedly thinned (Fig. 6 B). The infarcted myocardium was histologically characterized by a loss of myocardial fibres and severe fibrosis (Fig. 6 C-D). Apart from myocardial infarction, no other cardiac pathologies were observed. The lungs exhibited varying degrees of alveolar edema and congestion. Additionally, some lung tissue sections histologically displayed thickened and hypercellular alveolar walls, interpreted as either atelectasis (potentially postmortem) or interstitial pneumonia. Other examined organs were unremarkable. This comprehensive necropsy and examination protocol provided detailed insights into cardiac and systemic responses following the experimental interventions. Discussion This study demonstrates the feasibility of percutaneous MI induction (MI) in Göttingen mini-pigs, a model that closely replicates human cardiac anatomy and function. The utilization of advanced imaging modalities such as cardiac magnetic resonance imaging (MRI) and transthoracic echocardiography (TTE) allowed to validate the model in our study and demonstrate cardiac damages. By occlusion of the mid LAD (usually after the first diagonal branch) proven infarction of about 15% of the myocardium could by achieved with clinically relevant variability amount subjects. Clear changes in LVEF, as well as an increase in cardiac Troponin were observed confirming myocardial injury. Due to their body size and body weight, minipigs are particularly adapted to the implementation of advanced cardiac imaging, in particular MRI, which represents the gold standard for evaluating cardiac fibrosis and quantifying infarct size and tissue viability. Late gadolinium enhancement (LGE) imaging allowed for clear visualization of myocardial scars, correlating with histological findings. Similarly, TTE was easily feasible using protocols adapted to the mini-pig model. This combination of modalities provided a thorough and reliable framework for assessing the pathophysiological consequences of MI, setting a high benchmark for translational research. While the high degree of anatomical and functional similarity of the mini-pig heart to humans ensures the translational value of this model, particularly for studying interventions targeting post-MI remodeling and fibrosis, important limitations were also recognized in our work. First, we were not able to induced significant cardiac damage in all subjects, since in two animals vessel occlusion has to be interrupted due refractory ventricular fibrillation. Despite re-occlusion for a total period of 90 minutes, no myocardial fibrosis or reduced LVEF were observed despite significant elevation of troponin I. Second, there was a high variability in the extent of fibrosis among subjects, primarily due to anatomical differences and the location of the occluded coronary artery. Third, a relevant rhythmic instability occurred with induction of ventricular fibrillation in one fourth of the subjects, requiring reanimation in 3 with 1 death due to refractory ventricular fibrillation. Of note, this happened despite preemptive administration of lidocaine and amiodarone, continuous infusion of lidocaine and addition of magnesium when necessary. This strongly questions the ability to induce large infarction in minipigs used as a chronic model. In human cohorts, a similar high range of variability has been described with a mean percentage of myocardial scaring between 19 and 25% of the LV mass [ 18 – 20 ]. A cut-off of 24% has been associated with increased risks of remodeling and resorption of the infarction area occurred and resorption of the infarction occurred at 8 months, in particular in patients with microvascular obstruction at baseline[ 20 ]. In a dog model of infarction, infarct size observed in MRI at 3 days was 2%, 16%, and 23% of LV mass following 45-min, 90-min, and permanent LAD occlusions, respectively and important infarct resorption occurred at 4 weeks in particular in the reperfused groups [ 21 ]. This data align with our experienced and underly the difficulties to obtain large MI in chronic re-perfused animal models. Addressing these limitations may involve refining induction protocols, optimizing pharmacological strategies, or leveraging pre-procedural conditioning techniques to reduce electrical instability. The rather low mortality in our study may also be explained by ad hoc anaesthesia, careful post-operative monitoring and systematic regular checks. Animals were housed under optimal conditions, with extensive acclimatization and training to minimize stress and ensure welfare. Post-operative care included comprehensive pain management and monitoring, reflecting a commitment to animal well-being. Such standards not only ensure ethical compliance but also improve the reliability of experimental outcomes. Integrating cutting-edge imaging technologies, such as positron emission tomography (PET) or strain imaging, might provide deeper insights into metabolic and functional changes post-MI even in subjects with limited MI size. Conclusions In conclusion, the Göttingen mini-pig model represents a viable platform for studying myocardial infarction and its sequelae with high translational potential. By addressing its inherent challenges and leveraging its unique strengths, this model can play a pivotal role in advancing our understanding of MI pathophysiology and facilitating the development of novel therapeutic strategies. Declarations Authors Contribution NC, FP, and DC contributed to the conception and design of the manuscript. NB and MK performed the ultrasound examinations and collected the data. MB, YS, and CG analyzed the MRI images and collected the data. NC, MFP, FP, AWS, AH, and DC organized the animal experiments. SDB performed the necropsy. All authors critically reviewed the manuscript. Funding The study was funded by InnoSuisse Data Availability The datasets generated during and analyzed during the current study are available from the corresponding author on reasonable request. Ethical Approval The study was designed as a longitudinal, experimental, observational study. It was reviewed and approved by the Committee for Animal Experiments of the Canton of Bern, Switzerland (national number: 33492). For reporting methods and results of the present study, the ARRIVE guidelines were strictly followed Conflict of Interest The authors declare no competing interests. Clinical Trial Number Not applicable References Libby P (2001) Current concepts of the pathogenesis of the acute coronary syndromes. Circulation 104(3):365–372 Prabhu SD, Frangogiannis NG (2016) The Biological Basis for Cardiac Repair After Myocardial Infarction: From Inflammation to Fibrosis. Circ Res 119(1):91–112 McDonagh TA et al (2021) 2021 ESC Guidelines for the diagnosis and treatment of acute and chronic heart failure. Eur Heart J 42(36):3599–3726 Ahn D et al (2004) Induction of myocardial infarcts of a predictable size and location by branch pattern probability-assisted coronary ligation in C57BL/6 mice. Am J Physiol Heart Circ Physiol 286(3):H1201–H1207 Gao E et al (2010) A novel and efficient model of coronary artery ligation and myocardial infarction in the mouse. Circ Res 107(12):1445–1453 Krishnan A et al (2014) A detailed comparison of mouse and human cardiac development. Pediatr Res 76(6):500–507 Arlock P et al (2017) Ion currents of cardiomyocytes in different regions of the Gottingen minipig heart. J Pharmacol Toxicol Methods 86:12–18 Ding N et al (2021) Utility of Gottingen minipigs for the prediction of human pharmacokinetic profiles after intravenous drug administration. Drug Metab Pharmacokinet 41:100408 Wilkinson DJ et al (2017) Minipig and Human Metabolism of Aldehyde Oxidase Substrates: In Vitro-In Vivo Comparisons. AAPS J 19(4):1163–1174 Zhu L et al (2022) Detection of myocardial fibrosis: Where we stand. Front Cardiovasc Med 9:926378 Percie du Sert N et al (2020) The ARRIVE guidelines 2.0: Updated guidelines for reporting animal research. PLoS Biol 18(7):e3000410 Woodger T (2016) Restrainers in laboratory animal research. Lab Anim (NY) 45(8):310–311 Morton DB, Griffiths PH (1985) Guidelines on the recognition of pain, distress and discomfort in experimental animals and an hypothesis for assessment. Vet Rec 116(16):431–436 Petrucci M et al (2024) Mechanical and thermal thresholds before and after application of a conditioning stimulus in healthy Gottingen Minipigs. PLoS ONE 19(8):e0309604 Zoghbi WA et al (2017) Recommendations for Noninvasive Evaluation of Native Valvular Regurgitation: A Report from the American Society of Echocardiography Developed in Collaboration with the Society for Cardiovascular Magnetic Resonance. J Am Soc Echocardiogr 30(4):303–371 Lang RM et al (2015) Recommendations for cardiac chamber quantification by echocardiography in adults: an update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging. J Am Soc Echocardiogr 28(1):1–39e14 https://recoverinitiative.org/2012-guidelines. Wu E et al (2008) Infarct size by contrast enhanced cardiac magnetic resonance is a stronger predictor of outcomes than left ventricular ejection fraction or end-systolic volume index: prospective cohort study. Heart 94(6):730–736 Wu KC et al (1998) Prognostic significance of microvascular obstruction by magnetic resonance imaging in patients with acute myocardial infarction. Circulation 97(8):765–772 Lund GK et al (2007) Prediction of left ventricular remodeling and analysis of infarct resorption in patients with reperfused myocardial infarcts by using contrast-enhanced MR imaging. Radiology 245(1):95–102 Fieno DS et al (2004) Infarct resorption, compensatory hypertrophy, and differing patterns of ventricular remodeling following myocardial infarctions of varying size. J Am Coll Cardiol 43(11):2124–2131 Additional Declarations No competing interests reported. Supplementary Files S1SupplementalmaterialAnaesthesiaforMRIprocedures.docx Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-7373600","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":511935899,"identity":"2dfe347c-5fbb-4707-8347-cfe15d797b5b","order_by":0,"name":"Noé Corpataux","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA6klEQVRIie3OMQrCMBSA4YSCLoprRNAr1EXtbZK91CFLB5FIQZd2VxBzBV3E0SLEJQcQBNHFWRepm2kdpUY3wfyQN4R8vABgMv1+PlLDYgCyT14X0iFTAr8hcAj0pF0M1iDxD16FB+daedbxGqMBA/dVPnFCgWEoKUWi0KpOlojaMmYwkvnE3rm2BYeYMAFa6LpEZI4Is54/zCPdS0a4KN4QmSLC+UlHXJCRuSipLUyt2EENkcKOQ4lpU7jUGQv1MUlYHL0j2+B0THzs1Tfbxb7U6xM+2sTH+xuStlYHv9xow9oXJpPJ9L89ANzsVcU5x6PfAAAAAElFTkSuQmCC","orcid":"","institution":"Inselspital, University of Bern","correspondingAuthor":true,"prefix":"","firstName":"Noé","middleName":"","lastName":"Corpataux","suffix":""},{"id":511935900,"identity":"64cbfcb2-66b7-4cfa-bcee-284f9e410d0a","order_by":1,"name":"Maria Francesca Petrucci","email":"","orcid":"","institution":"University of Montreal","correspondingAuthor":false,"prefix":"","firstName":"Maria","middleName":"Francesca","lastName":"Petrucci","suffix":""},{"id":511935901,"identity":"b3c24d38-59bb-4d8f-8c33-e5fb1d1a4084","order_by":2,"name":"Fabien Praz","email":"","orcid":"","institution":"Inselspital, University of Bern","correspondingAuthor":false,"prefix":"","firstName":"Fabien","middleName":"","lastName":"Praz","suffix":""},{"id":511935902,"identity":"237a25dd-dfe6-40a8-8e72-13f12b2966a1","order_by":3,"name":"Anselm W. Stark","email":"","orcid":"","institution":"Inselspital, University of Bern","correspondingAuthor":false,"prefix":"","firstName":"Anselm","middleName":"W.","lastName":"Stark","suffix":""},{"id":511935903,"identity":"446dacfd-541b-4d9c-a04b-12381d7efa4e","order_by":4,"name":"Nicolas Brugger","email":"","orcid":"","institution":"Inselspital, University of Bern","correspondingAuthor":false,"prefix":"","firstName":"Nicolas","middleName":"","lastName":"Brugger","suffix":""},{"id":511935904,"identity":"4f48b78d-7bd6-470a-b7d4-a919be85e91d","order_by":5,"name":"Mohammad Kassar","email":"","orcid":"","institution":"Heart Center University of Bochum","correspondingAuthor":false,"prefix":"","firstName":"Mohammad","middleName":"","lastName":"Kassar","suffix":""},{"id":511935905,"identity":"871d9725-8f31-4ba0-8f61-da9417a44bfe","order_by":6,"name":"Martina Boscolo","email":"","orcid":"","institution":"Inselspital, University of Bern","correspondingAuthor":false,"prefix":"","firstName":"Martina","middleName":"","lastName":"Boscolo","suffix":""},{"id":511935906,"identity":"2374d5e1-9d20-41ec-b878-86f10c1e1f35","order_by":7,"name":"Yasaman Safarkhanlo","email":"","orcid":"","institution":"Inselspital, University of Bern","correspondingAuthor":false,"prefix":"","firstName":"Yasaman","middleName":"","lastName":"Safarkhanlo","suffix":""},{"id":511935909,"identity":"9877aa1d-c747-48d8-aec9-c143eb22fced","order_by":8,"name":"Andreas Haeberlin","email":"","orcid":"","institution":"Inselspital, University of Bern","correspondingAuthor":false,"prefix":"","firstName":"Andreas","middleName":"","lastName":"Haeberlin","suffix":""},{"id":511935911,"identity":"0183be75-142a-4cc6-bb32-6b9d7ae16e15","order_by":9,"name":"Simone de Brot","email":"","orcid":"","institution":"University of Bern","correspondingAuthor":false,"prefix":"","firstName":"Simone","middleName":"","lastName":"de Brot","suffix":""},{"id":511935913,"identity":"23f1f628-a215-46d1-a534-a1927cd635f5","order_by":10,"name":"Christoph Gräni","email":"","orcid":"","institution":"Inselspital, University of Bern","correspondingAuthor":false,"prefix":"","firstName":"Christoph","middleName":"","lastName":"Gräni","suffix":""},{"id":511935916,"identity":"2e83f40d-2e54-498f-a985-d75c007f19e8","order_by":11,"name":"Daniela Casoni","email":"","orcid":"","institution":"Heart Center University of Bochum","correspondingAuthor":false,"prefix":"","firstName":"Daniela","middleName":"","lastName":"Casoni","suffix":""}],"badges":[],"createdAt":"2025-08-14 11:53:27","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7373600/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7373600/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":91375163,"identity":"14a7e366-9a63-4b72-976c-5e7ba64b409a","added_by":"auto","created_at":"2025-09-15 19:53:55","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":61098,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cu\u003e\u003cstrong\u003eexperimental protocol\u003c/strong\u003e\u003c/u\u003e\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7373600/v1/2df0be13982d3b489761eccd.png"},{"id":91375398,"identity":"649b929d-0d31-48d4-baa2-58f1f425064d","added_by":"auto","created_at":"2025-09-15 20:01:55","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":472682,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cu\u003e\u003cstrong\u003eTransthoracic echocardiogram (TTE) at baseline and 35 days after iatrogenic myocardial infarction\u003c/strong\u003e\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eParasternal Long-Axis View at baseline (A and B) and post-infarction at 35 days follow-up (C and D)\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eRed circle: Myocardium thinning and absence of systolic contraction antero-septal\u003c/em\u003e\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7373600/v1/ce42327232823f0c19fc8e6e.png"},{"id":91375170,"identity":"8f212c75-bd37-44e8-8029-b871e325edce","added_by":"auto","created_at":"2025-09-15 19:53:55","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":187862,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cu\u003e\u003cstrong\u003eiatrogenic myocardial infarction procedure\u003c/strong\u003e\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eLAO 25 Grad view. Diagnostic angiography after wiring the left anterior descending artery (LAD) with a workhorse wire (A) and occlusion of the mid LAD after the first diagonal branch with a 2.5x9mm compliant balloon (B).\u003c/em\u003e\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7373600/v1/244b68327c1142946a9fc9e7.png"},{"id":91375168,"identity":"0f8bc83f-82c5-4dc4-bec9-c8d3592cdf4a","added_by":"auto","created_at":"2025-09-15 19:53:55","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":36599,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cu\u003e\u003cstrong\u003eLVEF, myocardial fibrosis and troponin values post myocardial infarction\u003c/strong\u003e\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eLGE = late gadolinium enhancement; LVEF = left ventricular ejection fraction\u003c/em\u003e\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-7373600/v1/8508cc2fd375373c097a9e65.png"},{"id":91375171,"identity":"91583f7a-5643-4dfe-816b-3c5af179e276","added_by":"auto","created_at":"2025-09-15 19:53:55","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":350079,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cu\u003e\u003cstrong\u003eMRI 46 days after iatrogenic myocardial infarction\u003c/strong\u003e\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eLGE = late gadolinium enhancement; SSFP = steady-state free precession\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eGreen arrow: \u0026nbsp;Anterior akinesia/diskinesia (midventricular to apical) in 2CH vie\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eGreen circle: \u0026nbsp;Akinesia/diskinesia anteroseptal (midventricular to apical) in 3CH view\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eRed arrow: subendocardial myocardial scar anterior (midventricular to apical) and with almost 100% transmurality in 2CH view\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eRed circle: subendocardial myocardial scar anteroseptal (midventricular to apical) with almost 100% transmurality in 2CH view = non-viable scar.\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eIn this example, this non-viable scar weighs about 7.8g, which corresponds to 15% of the total muscle mass.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-7373600/v1/1bc48bb40f7e6dcc994ab49f.png"},{"id":91375182,"identity":"4d75fed9-4526-41d5-8496-6e0f0d965996","added_by":"auto","created_at":"2025-09-15 19:53:55","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":748428,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cu\u003e\u003cstrong\u003eHistological features of the infarcted pig heart\u003c/strong\u003e\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eHistological changes in the pig heart after myocardial infarction procedure. \u003c/em\u003e\u003cem\u003e\u003cstrong\u003eA-B\u003c/strong\u003e\u003c/em\u003e\u003cem\u003emacroscopic examination is consistent with the MRI and ultrasound findings with myocardium thinning. \u003c/em\u003e\u003cem\u003e\u003cstrong\u003eC\u003c/strong\u003e\u003c/em\u003e\u003cem\u003eMicrophotograph of the heart (left ventricle) with x5 magnification of the hematoxylin and eosin HE (C) and Masson Trichrome (D). Focally extensive chronic cardiac infarct is evident, characterized by fibrosis which replaces affected myocardial tissue. Fibrosis is stained green on Masson Trichrome tissue sections\u003c/em\u003e\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-7373600/v1/8bd66ccfb96803d39037105d.png"},{"id":96363130,"identity":"c1d4945d-1717-476f-84f3-ef4994eaff07","added_by":"auto","created_at":"2025-11-20 10:04:52","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3016306,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7373600/v1/1bdb9273-525e-4904-b216-d6225f3abb17.pdf"},{"id":91375397,"identity":"819a71b7-15fe-4f60-953c-c93c3cca928d","added_by":"auto","created_at":"2025-09-15 20:01:55","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":14743,"visible":true,"origin":"","legend":"","description":"","filename":"S1SupplementalmaterialAnaesthesiaforMRIprocedures.docx","url":"https://assets-eu.researchsquare.com/files/rs-7373600/v1/15868c3ea2a8b45a162147e4.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Feasibility of a Göttingen mini-pig mini-invasive model for myocardial infarction induction","fulltext":[{"header":"Introduction","content":"\u003cp\u003eMyocardial infarction (MI) is a critical cardiovascular emergency characterized by the abrupt loss of cardiomyocytes and subsequent myocardial remodeling. This pathological process frequently results in the formation of collagen-based scar tissue [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e], which compromises myocardial function and predisposes patients to heart failure with reduced ejection fraction (HFrEF). HFrEF remains a significant global health burden, marked by debilitating symptoms, poor quality of life, and high mortality rates [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Effective therapeutic interventions for MI and its sequelae rely heavily on preclinical investigations on animal models that closely replicate the human pathophysiology of ischemic heart disease.\u003c/p\u003e\u003cp\u003eMurine models have traditionally been employed to investigate MI, owing to their genetic tractability and cost-effectiveness [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. However, the inherent structural and functional disparities between rodent and human hearts limit their translational applicability. In particular, murine hearts exhibit a much higher heart rate, smaller size, and distinct myocardial composition compared to humans [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. These differences can hinder the clinical relevance of findings, especially when studying myocardial remodeling, fibrosis, and therapeutic interventions. As a result, the demand for larger animal models better approximating human cardiac physiology is increasing.\u003c/p\u003e\u003cp\u003ePorcine models, particularly Göttingen mini-pigs, are considered an attractive alternative to rodents for preclinical cardiovascular research. Their cardiac anatomy, size, and functional parameters closely resemble those of humans, making them well suited for translational studies [\u003cspan additionalcitationids=\"CR8\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e–\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. The body size and weight of minipigs are of advantage for advanced imaging modalities, such as cardiac magnetic resonance imaging (MRI) and transthoracic echocardiography (TTE), which provides an unparalleled opportunity for detailed assessment of cardiac function, volume, and tissue characterization. MRI is the gold standard for evaluating myocardial fibrosis and left ventricular remodeling post-MI [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e], enabling high-resolution, clinically relevant analyses helping to bridge the gap between animal studies and human applications.\u003c/p\u003e\n\u003ch3\u003eRationale\u003c/h3\u003e\n\u003cp\u003eThe goal of this report is to describe the feasibility, viability, and translational value of a Göttingen mini-pig model used for mini-invasive MI induction. We describe the outcomes of the control arm of a randomized control trial investigating new therapeutic approaches for the chronic treatment of ischemic heart disease.\u003c/p\u003e\u003cp\u003eMyocardial ischemia was induced occluding the left anterior descending artery to replicate the pathophysiological cascade of human MI and was followed by successful myocardial reperfusion. Echocardiographic protocols adapted to the anatomical features of the mini-pig heart, were used to assess the cardiac damage overt time and its consequences on heart function while biomarkers were measured to quantify the cardiac damage. Advanced imaging techniques, including cine MRI and late gadolinium enhancement (LGE), were integrated to ensure precise characterization of infarct size, myocardial remodeling, and fibrosis.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e This study was conducted in accordance with the legislation of the Swiss Federal Food Safety and Veterinary Office. The experimental protocol was reviewed and approved by the Cantonal Committee for Animal Experiments of Bern, Switzerland (authorization number: 33492). All methods were carried out in compliance with the relevant institutional and national guidelines for animal research [\u003cspan additionalcitationids=\"CR12\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e–\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e], and the reporting of methods and results adheres to the ARRIVE guidelines.\u003c/p\u003e\u003ch3\u003eAnimal cohort\u003c/h3\u003e\u003cp\u003eTwelve adult female and male minipigs (5 females, 7 males; age 12–18 months; weight 27.3 ± 4.1 kg) were purchased from their official breeder Ellegaard Göttingen Minipigs (Dalmose, Denmark), a specific-pathogen-free herd. At least 2 weeks before the start of the trial, the animals were transported to Switzerland, where they were hosted in groups of six to ten in an 18m² pen with a 50m² outdoor area, located on a farm. Water was available ad libitum, and food (Minipigs Maintenance Standard, Kliba Nafag, Switzerland) was provided twice per day (800 grams/minipig/day)[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Physiological and behavioral evaluations were carried out at least three time per week before the beginning of the trial. Further details on animals and housing conditions have been previously published [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eAt least 24 hours before MI induction, minipigs were transported in groups of two from the hosting farm to the Experimental Surgery Facility (ESF) of the University of Bern. There, they were hosted together in the large animal intensive care unit in a box (length: 2.07 x width: 1.68 x height: 2.50 square meters) Before anaesthesia, minipigs were fasted for 8–12 hours while water remained available ad libitum.\u003c/p\u003e\u003cp\u003ePigs were recovered from general anaesthesia after the procedures in the same boxes wherthey were monitored for at least 15 hours after reaching sternal recumbency. The animals were transported back to the farm only when deemed hemodynamically stable and pain-free. Minipigs were kept at the farm until the study endpoint. Veterinary checks were carried out daily from post-operative (PO) day 1 to PO day 7, and from PO day 8 to PO day 45 at least three times per week. Body weight was checked daily until PO day 3, and then once per week until the study endpoint.\u003c/p\u003e\u003cp\u003eOn the study endpoint, the minipigs were transported from the farm to the ESF where they were anaesthetised to undergo cardiac magnetic resonance imaging (MRI). Following preanesthetic clinical examination and premedication, they were transported to the TIC-SITEM of the University of Bernn, where preparation for general anaesthesia was accomplished and the scan was carried out. At the end of the diagnostic procedure, minipigs were euthanized under general anaesthesia with an intravenous overdose of pentobarbital (100 mg/kg). Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e presents the experimental protocol as a graphical timeline.\u003c/p\u003e\u003ch3\u003eTransthoracic echocardiography\u003c/h3\u003e\u003cp\u003eTransthoracic echocardiogram (TTE) at baseline and 35 to 45 days after iatrogenic myocardial infarction was performed under sedation. Minipigs were injected with IM midazolam 1 mg/kg and ketamine 2 mg/kg during the procedure, oxygen was continuously administered through a face mask (6 L/min) and monitoring consisted of a pulse-oximeter (SpO\u003csub\u003e2\u003c/sub\u003e and pulse rate and width) placed on the ear and electrocardiogram (ECG). In case of insufficient sedation, further 0.2 mg/kg midazolam was injected IM.\u003c/p\u003e\u003cp\u003eThe images were acquired using a ACUSON SC2000 PRIME ultrasound system (Siemens Healthcare GmbH, Eschborn, Germany) equipped with a 5V1 probe. For the recording of the various echocardiographic views, the mini-pigs had to lie in right lateral recumbency, on a dedicated examination table according to the anatomical location of their heart. Due to the absence of a specific echocardiographic protocol for the evaluation of mini-pigs, we adapted the ASE guidelines [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e] according to their specific anatomy, to perform a comprehensive echocardiogram. The lines density and the image depth were adapted to obtain a time resolution of at least 50fps in B-Mode and 20fps in color-Doppler mode. The highest frequency providing an adequate penetration of the ultrasounds was utilized to optimize the spatial resolution. The sweep speed for all spectral Doppler recordings was set to 75–100 mm/s.\u003c/p\u003e\u003cp\u003eAt the beginning of the examination, the pigs were gently positioned on their left side, allowing access to the parasternal right echographic windows at the level of the right anterior limb. The views acquired in this position were the parasternal long-axis (PLAX) and multiples parasternal short-axis (SAX) views. The PLAX view (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) provided a longitudinal section of the heart, allowing assessment of the left ventricle (LV, posterior and antero-septal walls), mitral valve, and aortic valve. The cross-sectional SAX views were used to assess wall motion abnormalities in all the LV segments. Afterward the pigs were gently turned on their right side for acquisition of a two chambers (2CV) view. The LV volumes and LV ejection fraction were calculated using the Simpson's method of discs after tracing the LV endocardial borders at the end of the diastole and of the systole in 4CV and 2CV.\u003c/p\u003e\u003cp\u003eFlumazenil 0.01–0.02 mg/kg (Flumazenil 0.5 mg/5 ml, Labatec Pharma) IM was administered at the end of the procedure if no signs of recovery were present within 60 minutes after injection of sedative drugs.\u003c/p\u003e\u003ch3\u003eCardiac MRI examination\u003c/h3\u003e\u003cp\u003eCardiac MRI scans were conducted 42 ± 3 days days post-infarction under general anesthesia as described in the supplemental material S1 using a 3T scanner (Prisma, Siemens, Erlangen, Germany) in all animals. A baseline cardiac MRI was performed in 4 subjects during our early experience Cine steady-state free precession (SSFP) images were acquired to assess left ventricular (LV) function and LV mass. The cine imaging was performed in 10–12 short-axis planes (TE = 1.35 ms; 8 mm thick with no gap, in-plane spatial resolution, 1.3 × 1.3 mm) and 3 radial long-axis planes.\u003c/p\u003e\u003cp\u003eTo discern areas of fibrosis, a supplementary late gadolinium enhancement (LGE) imaging protocol was used. This involved a segmented inversion-recovery pulse sequence, initiated 10 to 15 minutes after injecting 7.5 ml of gadolinium diethylenetriamine pentaacetic acid (Magnevist, Bayer HealthCare Pharmaceuticals Inc., Wayne, New Jersey). The LGE protocol allowed for enhanced visualization and quantification of myocardial scarring, particularly in the subendocardial region of the left anterior descending artery (LAD) flow area. The details of anaesthesia for MRI are reported in the supplemental material.\u003c/p\u003e\u003ch3\u003eInduction of myocardial infarction\u003c/h3\u003e\u003cp\u003eMyocardial infarction was induced in general anaesthesia. Briefly, minipigs were sedated with IM injection of 0.2 mg/kg morphine 10 mg/kg ketamine and 15 mcg/kg dexmedetomine mixed in the same syringeIf sedation was deemed inadequate 15 minutes after injection, 0.2 mg/kg midazolam was injected IM.\u003c/p\u003e\u003cp\u003eGeneral anaesthesia was induced with intravenous ketamine 1 mg/kg and propofol 1–3 mg/Kg titrated to accomplish tracheal intubation. Following tracheal intubation, the animals were allowed to breath in a spontaneous pressure supported mode, if normocapnia could be maintained. Otherwise volume controlled, pressure limited ventilation was started. Anaesthesia was deepened and maintained with sevoflurane in oxygen and compressed air (60 − 40%). End tidal sevoflurane was adjusted to guarantee adequate depth of anaesthesia up to its MAC (2.7%). Amoxicillin-clavulanic acid 20 mg/kg was administered IV.\u003c/p\u003e\u003cp\u003eLidocaine 30 µg/kg/min (Lidocaine 1%, Streuli Pharma AG) continuous rate infusion (CRI) was infused during the all procedure. Monitoring of HR and rhythm (II lead as basis), respiratory rate, SpO2, capnography, invasive blood pressure, oesophageal temperature, inhaled and exhaled fraction of gases (air, ETCO2), central venous pressure was performed through a multimodal monitor Electroencephalographic activity (EEG) was monitored through surface electrodes positioned on the forehead. Mild hypothermia (35–36◦C) was targeted along the whole intervention and maintained with the help of a forced air device.\u003c/p\u003e\u003cp\u003eBefore LAD catheterisation, amiodarone 5 mg/kg was administered over 1 hour in CRI. Activated clotting time (ACT) was assessed and a bolus of heparin 80 I.U./kg was administered, followed by CRI (30–80 I.U./kg/h). Heparin rate was adjusted by targeting ACT values of 2–3 times its baseline value after arterial catheter insertion.\u003c/p\u003e\u003cp\u003eWith the animals positioned in dorsal recumbency, the femoral access was established percutaneously under ultrasound guidance using a modified Seldinger’s technique. A 6 French arterial vascular sheath was then inserted into the femoral artery and sutured in place.\u003c/p\u003e\u003cp\u003eStandard catheter shapes designed for human procedures, such as Judkins left and right (JL and JR), were employed to gain selective coronary access. Subsequently, a workhorse coronary wire was engaged in the distal left anterior descending artery (LAD), as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. A visually sized balloon (usually 2.5mm) was introduced and inflated in the midsection of the artery, after the first diagonal branch. In presence of a large intermediate branch, the balloon was inflated proximally to the first diagonal branch. Complete vessel occlusion was confirmed through the injection of contrast medium. The balloon was maintained in place for 90 minutes and then deflated. Two-hours reperfusion in general anaesthesia followed the ischemia. At the end of the procedure, the arterial vascular sheath was extracted, and the puncture site was manually compressed for 5 to 10 minutes.\u003c/p\u003e\u003cp\u003eIf ventricular fibrillation occurred, cardiopulmonary resuscitation including external defibrillation was carried out based on guidelines for small animals[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Minipigs were declared dead intraoperatively if ventricular fibrillation led to cardiac arrest unresponsive to cardiopulmonary resuscitation and defibrillation (ROSC not achieved within 30 minutes following cardiac arrest).\u003c/p\u003e\u003ch2\u003eNecropsy\u003c/h2\u003e\u003cp\u003eImmediately after euthanasia, post-mortem examination and tissue collection was performed by a board-certified veterinary pathologist (SdB). Prior to sampling for histology, the heart was examined for the presence and extent of cardiac infarct and the heart weight was recorded. For histologic analysis, tissue samples were collected from aorta (ascending, arch, descending), heart (atrium right and left, ventricle right and left, septum, infarct zone, infarct border zone, infarct remote zone), spleen, liver, and kidney. The tissues were placed in 10% neutral buffered formalin for a minimum of 48h and then routinely processed and stained with haematoxylin and eosin (HE) for histologic examination. Cardiac tissue sections were additionally stained with Masson Trichrome for the evaluation of fibrosis.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eTwelve Ellegaard G\u0026ouml;ttingen Minipigs, 5 females and 7 males, aged 15.5\u0026thinsp;\u0026plusmn;\u0026thinsp;2.1 months and weighing 27.3\u0026thinsp;\u0026plusmn;\u0026thinsp;4.1 kg underwent MI induction between august 2022 and October 2023. The procedure could be performed successfully mini-invasively with a percutaneous approach in all subjects (100%). Because of ventricular fibrillation with cardiac arrest unresponsive to first defibrillation, the balloon in the mid LAD was temporarily deflated in three pigs (25%). After successful resuscitation and restoration of sinus rhythm, the balloon could be re-inflated in two pigs to achieve the fixed infarction time of 90 minutes. One animal (8%) died during procedure due to refractory ventricular fibrillation. Eleven minipigs were discharged from the Experimental Surgery Facility if in good clinical conditions the day after the procedure and transported back to the farm.\u003c/p\u003e\u003cp\u003eComprehensive cardiac assessments revealed significant post-infarction changes in 9 out of 11 mini-pigs. Among the animals that underwent cardiac MRI at both baseline and follow-up, myocardial fibrosis increased to 10.25\u0026thinsp;\u0026plusmn;\u0026thinsp;5.4%, while LVEF decreased from 54\u0026thinsp;\u0026plusmn;\u0026thinsp;3.8% to 43.3\u0026thinsp;\u0026plusmn;\u0026thinsp;3.56% (p\u0026thinsp;\u0026lt;\u0026thinsp;0.01). Left ventricular volumes also increased, indicating adverse LV remodeling, with the mean LVEDV rising from 66.55\u0026thinsp;\u0026plusmn;\u0026thinsp;9.5 ml at baseline to 73.83\u0026thinsp;\u0026plusmn;\u0026thinsp;12.3 ml post-infarction (p\u0026thinsp;=\u0026thinsp;0.11). Across the entire cohort, the mean post-infarction LVEF was 42.8\u0026thinsp;\u0026plusmn;\u0026thinsp;4.3%, and myocardial fibrosis reached 15.5\u0026thinsp;\u0026plusmn;\u0026thinsp;10.5%, with substantial variability in infarct size and fibrosis percentage among animals, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. Troponin I levels, measured 13 to 18 hours post-infarction, confirmed myocardial injury with a mean value of 3093\u0026thinsp;\u0026plusmn;\u0026thinsp;1156 pg/ml.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eIn the two animals where vessel occlusion was interrupted due to refractory ventricular fibrillation, no myocardial fibrosis (LGE/Mass\u0026thinsp;=\u0026thinsp;0%) or abnormal LVEF (57% and 52%) were observed post-infarction, despite elevated troponin I levels (3567 and 1802 pg/ml).\u003c/p\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec-d \u003cb\u003eand\u003c/b\u003e Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e illustrate the findings of the post-infarction ultrasound and MRI, revealing myocardium thinning with absence of systolic contraction as well as akinesia and dyskinesia attributable to subendocardial myocardial scarring in the LAD flow area.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\n\u003ch3\u003eNecropsy\u003c/h3\u003e\n\u003cp\u003eRelevant macroscopic findings were primarily observed in the lungs and heart. Evidence of a white cardiac infarct was observed at the apex, characterized by a focal, variably well-defined, pale and firm myocardial region, indicative of cardiac fibrosis (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eA). As previously demonstrated by MRI, the extent of cardiac infarct varied between different heart locations and animals. Upon incision, the affected left ventricular wall was markedly thinned (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eB). The infarcted myocardium was histologically characterized by a loss of myocardial fibres and severe fibrosis (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eC-D).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eApart from myocardial infarction, no other cardiac pathologies were observed. The lungs exhibited varying degrees of alveolar edema and congestion. Additionally, some lung tissue sections histologically displayed thickened and hypercellular alveolar walls, interpreted as either atelectasis (potentially postmortem) or interstitial pneumonia. Other examined organs were unremarkable. This comprehensive necropsy and examination protocol provided detailed insights into cardiac and systemic responses following the experimental interventions.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study demonstrates the feasibility of percutaneous MI induction (MI) in G\u0026ouml;ttingen mini-pigs, a model that closely replicates human cardiac anatomy and function. The utilization of advanced imaging modalities such as cardiac magnetic resonance imaging (MRI) and transthoracic echocardiography (TTE) allowed to validate the model in our study and demonstrate cardiac damages. By occlusion of the mid LAD (usually after the first diagonal branch) proven infarction of about 15% of the myocardium could by achieved with clinically relevant variability amount subjects. Clear changes in LVEF, as well as an increase in cardiac Troponin were observed confirming myocardial injury.\u003c/p\u003e\u003cp\u003eDue to their body size and body weight, minipigs are particularly adapted to the implementation of advanced cardiac imaging, in particular MRI, which represents the gold standard for evaluating cardiac fibrosis and quantifying infarct size and tissue viability. Late gadolinium enhancement (LGE) imaging allowed for clear visualization of myocardial scars, correlating with histological findings. Similarly, TTE was easily feasible using protocols adapted to the mini-pig model. This combination of modalities provided a thorough and reliable framework for assessing the pathophysiological consequences of MI, setting a high benchmark for translational research.\u003c/p\u003e\u003cp\u003eWhile the high degree of anatomical and functional similarity of the mini-pig heart to humans ensures the translational value of this model, particularly for studying interventions targeting post-MI remodeling and fibrosis, important limitations were also recognized in our work. First, we were not able to induced significant cardiac damage in all subjects, since in two animals vessel occlusion has to be interrupted due refractory ventricular fibrillation. Despite re-occlusion for a total period of 90 minutes, no myocardial fibrosis or reduced LVEF were observed despite significant elevation of troponin I. Second, there was a high variability in the extent of fibrosis among subjects, primarily due to anatomical differences and the location of the occluded coronary artery. Third, a relevant rhythmic instability occurred with induction of ventricular fibrillation in one fourth of the subjects, requiring reanimation in 3 with 1 death due to refractory ventricular fibrillation. Of note, this happened despite preemptive administration of lidocaine and amiodarone, continuous infusion of lidocaine and addition of magnesium when necessary. This strongly questions the ability to induce large infarction in minipigs used as a chronic model.\u003c/p\u003e\u003cp\u003eIn human cohorts, a similar high range of variability has been described with a mean percentage of myocardial scaring between 19 and 25% of the LV mass [\u003cspan additionalcitationids=\"CR19\" citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. A cut-off of 24% has been associated with increased risks of remodeling and resorption of the infarction area occurred and resorption of the infarction occurred at 8 months, in particular in patients with microvascular obstruction at baseline[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. In a dog model of infarction, infarct size observed in MRI at 3 days was 2%, 16%, and 23% of LV mass following 45-min, 90-min, and permanent LAD occlusions, respectively and important infarct resorption occurred at 4 weeks in particular in the reperfused groups [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. This data align with our experienced and underly the difficulties to obtain large MI in chronic re-perfused animal models. Addressing these limitations may involve refining induction protocols, optimizing pharmacological strategies, or leveraging pre-procedural conditioning techniques to reduce electrical instability. The rather low mortality in our study may also be explained by ad hoc anaesthesia, careful post-operative monitoring and systematic regular checks. Animals were housed under optimal conditions, with extensive acclimatization and training to minimize stress and ensure welfare. Post-operative care included comprehensive pain management and monitoring, reflecting a commitment to animal well-being. Such standards not only ensure ethical compliance but also improve the reliability of experimental outcomes. Integrating cutting-edge imaging technologies, such as positron emission tomography (PET) or strain imaging, might provide deeper insights into metabolic and functional changes post-MI even in subjects with limited MI size.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eIn conclusion, the G\u0026ouml;ttingen mini-pig model represents a viable platform for studying myocardial infarction and its sequelae with high translational potential. By addressing its inherent challenges and leveraging its unique strengths, this model can play a pivotal role in advancing our understanding of MI pathophysiology and facilitating the development of novel therapeutic strategies.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAuthors Contribution\u003c/strong\u003e NC, FP, and DC contributed to the conception and design of the manuscript. NB and MK performed the ultrasound examinations and collected the data. MB, YS, and CG analyzed the MRI images and collected the data. NC, MFP, FP, AWS, AH, and DC organized the animal experiments. SDB performed the necropsy. All authors critically reviewed the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e The study was funded by InnoSuisse\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability\u003c/strong\u003e The datasets generated during and analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical\u003c/strong\u003e \u003cstrong\u003eApproval\u003c/strong\u003e The study was designed as a longitudinal, experimental, observational study. It was reviewed and approved by the Committee for Animal Experiments of the Canton of Bern, Switzerland (national number: 33492). For reporting methods and results of the present study, the ARRIVE guidelines were strictly followed\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of Interest\u003c/strong\u003e The authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eClinical Trial Number\u003c/strong\u003e Not applicable\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eLibby P (2001) Current concepts of the pathogenesis of the acute coronary syndromes. Circulation 104(3):365\u0026ndash;372\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePrabhu SD, Frangogiannis NG (2016) The Biological Basis for Cardiac Repair After Myocardial Infarction: From Inflammation to Fibrosis. Circ Res 119(1):91\u0026ndash;112\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMcDonagh TA et al (2021) 2021 ESC Guidelines for the diagnosis and treatment of acute and chronic heart failure. Eur Heart J 42(36):3599\u0026ndash;3726\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAhn D et al (2004) Induction of myocardial infarcts of a predictable size and location by branch pattern probability-assisted coronary ligation in C57BL/6 mice. Am J Physiol Heart Circ Physiol 286(3):H1201\u0026ndash;H1207\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGao E et al (2010) A novel and efficient model of coronary artery ligation and myocardial infarction in the mouse. Circ Res 107(12):1445\u0026ndash;1453\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKrishnan A et al (2014) A detailed comparison of mouse and human cardiac development. Pediatr Res 76(6):500\u0026ndash;507\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eArlock P et al (2017) Ion currents of cardiomyocytes in different regions of the Gottingen minipig heart. J Pharmacol Toxicol Methods 86:12\u0026ndash;18\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDing N et al (2021) Utility of Gottingen minipigs for the prediction of human pharmacokinetic profiles after intravenous drug administration. Drug Metab Pharmacokinet 41:100408\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWilkinson DJ et al (2017) Minipig and Human Metabolism of Aldehyde Oxidase Substrates: In Vitro-In Vivo Comparisons. AAPS J 19(4):1163\u0026ndash;1174\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZhu L et al (2022) Detection of myocardial fibrosis: Where we stand. Front Cardiovasc Med 9:926378\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePercie du Sert N et al (2020) The ARRIVE guidelines 2.0: Updated guidelines for reporting animal research. PLoS Biol 18(7):e3000410\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWoodger T (2016) Restrainers in laboratory animal research. Lab Anim (NY) 45(8):310\u0026ndash;311\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMorton DB, Griffiths PH (1985) Guidelines on the recognition of pain, distress and discomfort in experimental animals and an hypothesis for assessment. Vet Rec 116(16):431\u0026ndash;436\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePetrucci M et al (2024) Mechanical and thermal thresholds before and after application of a conditioning stimulus in healthy Gottingen Minipigs. PLoS ONE 19(8):e0309604\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZoghbi WA et al (2017) Recommendations for Noninvasive Evaluation of Native Valvular Regurgitation: A Report from the American Society of Echocardiography Developed in Collaboration with the Society for Cardiovascular Magnetic Resonance. J Am Soc Echocardiogr 30(4):303\u0026ndash;371\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLang RM et al (2015) Recommendations for cardiac chamber quantification by echocardiography in adults: an update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging. J Am Soc Echocardiogr 28(1):1\u0026ndash;39e14\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003e\u003cem\u003ehttps://recoverinitiative.org/2012-guidelines.\u003c/em\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWu E et al (2008) Infarct size by contrast enhanced cardiac magnetic resonance is a stronger predictor of outcomes than left ventricular ejection fraction or end-systolic volume index: prospective cohort study. Heart 94(6):730\u0026ndash;736\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWu KC et al (1998) Prognostic significance of microvascular obstruction by magnetic resonance imaging in patients with acute myocardial infarction. Circulation 97(8):765\u0026ndash;772\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLund GK et al (2007) Prediction of left ventricular remodeling and analysis of infarct resorption in patients with reperfused myocardial infarcts by using contrast-enhanced MR imaging. Radiology 245(1):95\u0026ndash;102\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFieno DS et al (2004) Infarct resorption, compensatory hypertrophy, and differing patterns of ventricular remodeling following myocardial infarctions of varying size. J Am Coll Cardiol 43(11):2124\u0026ndash;2131\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Myocardial infarction induction, Minimally invasive model, Göttingen mini-pig, Cardiac magnetic resonance imaging (CMR), Translational cardiology, Fibrosis quantification","lastPublishedDoi":"10.21203/rs.3.rs-7373600/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7373600/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eMyocardial infarction (MI) remains a major research focus, with efforts aimed at preserving myocardial cells and reducing fibrosis. Survival animal models are crucial for studying MI but present challenges due to disease severity and potential animal suffering. In this study, ischemia was induced in 12 Göttingen mini-pigs using transcatheter balloon occlusion of the left anterior descending artery, followed by 90 minutes of ischemia and 2 hours of reperfusion. Transthoracic echocardiography and MRI were performed before and after MI using dedicated imaging protocols. Three animals (25%) experienced ventricular fibrillation; two were successfully resuscitated, while one died. Significant post-infarction changes were observed, with a mean ejection fraction of 43% and myocardial fibrosis of 15.5%. In the subset of animals that didn’t experienced ventricular fibrillation, fibrosis increased by 10.25 ± 5.4%, while ejection fraction declined from 54 ± 3.8% to 43.3 ± 3.56% (p \u0026lt; 0.01). These findings suggest that this minimally invasive model is a viable approach for MI research, although the risk of lethal arrhythmias remains a concern in cases of large infarcts.\u003c/p\u003e","manuscriptTitle":"Feasibility of a Göttingen mini-pig mini-invasive model for myocardial infarction induction","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-15 19:53:50","doi":"10.21203/rs.3.rs-7373600/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"ebb57f80-7b2a-48d7-85a7-d953a93ae28f","owner":[],"postedDate":"September 15th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-11-16T17:08:32+00:00","versionOfRecord":[],"versionCreatedAt":"2025-09-15 19:53:50","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7373600","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7373600","identity":"rs-7373600","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}