Transcatheter Management of Atypical Scimitar Syndromes With Dual Venous Drainage.

This 34-year-old woman was born at full term with an uneventful neonatal history. Her medical background included untreated asthma and recurrent bronchitis since childhood. She had experienced 2 uneventful pregnancies, with no significant worsening of exertional dyspnea or development of additional cardiopulmonary symptoms. While awaiting surgical repair for a right inguinal hernia, she reported NYHA class II dyspnea. Physical examination revealed normal oxygen saturation, no signs of heart failure, and adequate peripheral perfusion. A chest CT scan performed as part of the workup for recurrent respiratory infections revealed a single right SV with dual drainage ( Figure 4 ): One pathway drained into the IVC with a severely stenotic junction ( Figure 5A ), and the other connected to the left inferior pulmonary vein ( Figure 5B ) via a large accessory fistulous vein ( Figure 5C ). No evidence of right-lung hypoplasia or SA supply sequestration artery was found. Figure 4 Patient 3: Scimitar Syndrome in 34 Years of Age With Before-the-Procedure 3D Modeling of the Cardiac Anatomy Figure 5 Patient 3: Scimitar Syndrome in 34 Years of Age With Before the Procedure (A) Cardiac gated CT scan arterial phase MIP oblique (Ge Revolution Apex CT 100 keV 268 mAs). (B) Three-dimensional VR reconstruction in posterior view (Ge Revolution Apex CT). (C) Selective arteriographic imaging of the right pulmonary lower lobe (Philips Azurion). Yellow arrow: Partial anomalous pulmonary venous return: right pulmonary vein draining abnormally into the inferior vena cava. Green arrow: Accessory pulmonary vein also connected and draining into the left inferior pulmonary vein and then to the left atrium. Patient 3: Scimitar Syndrome in 34 Years of Age With Before-the-Procedure 3D Modeling of the Cardiac Anatomy Patient 3: Scimitar Syndrome in 34 Years of Age With Before the Procedure (A) Cardiac gated CT scan arterial phase MIP oblique (Ge Revolution Apex CT 100 keV 268 mAs). (B) Three-dimensional VR reconstruction in posterior view (Ge Revolution Apex CT). (C) Selective arteriographic imaging of the right pulmonary lower lobe (Philips Azurion). Yellow arrow: Partial anomalous pulmonary venous return: right pulmonary vein draining abnormally into the inferior vena cava. Green arrow: Accessory pulmonary vein also connected and draining into the left inferior pulmonary vein and then to the left atrium. Cardiac MRI showed moderate right-heart-chamber dilation and a Qp/Qs ratio of 1.6, meeting the criteria for intervention due to significant left-to-right shunting. Following multidisciplinary discussion and in accordance with the patient's preferences, a transcatheter approach was selected. The procedure was performed under local anesthesia via right and left femoral venous access. Pulmonary artery pressures were within normal limits. Oximetric analysis confirmed a significant left-to-right shunt, with a Qp/Qs ratio approaching 2. Angiography demonstrated dual drainage of the right pulmonary vein: one into the pulmonary vein, and the other into the IVC, with a stenotic (jammed) junction. A balloon occlusion test using a 24-mm compliant balloon ( Figure 6A ) confirmed stable SV pressure and successful angiographic redirection of venous flow toward the left inferior pulmonary vein. Based on these results, a 12 × 10-mm Amplatzer Duct Occluder I (Abbott) was deployed at the IVC junction, with satisfactory positioning and flow exclusion ( Figure 6B ). Aspirin was prescribed for 6 months to promote endothelialization of the device ( Video 1 ). Figure 6 Patient 3: Scimitar Syndrome in 34 Years of Age After the Procedure (A) Per procedure arteriographic imaging showed satisfactory ballon occlusion simulation of right inferior pulmonary lobe partial anomalous pulmonary venous return (PAPVR) with redirection of pulmonary venous flow toward the accessory vein draining into the left atrium. (B) Per procedure arteriographic imaging then demonstrated optimal positioning of occluder. (C) Postprocedural 3-month arterial-phase CT scan confirmed satisfactory positioning of the occluder with effective sealing of the PAPVR, no sign of device-related complications, and absence of residual left-to-right shunting. Patient 3: Scimitar Syndrome in 34 Years of Age After the Procedure (A) Per procedure arteriographic imaging showed satisfactory ballon occlusion simulation of right inferior pulmonary lobe partial anomalous pulmonary venous return (PAPVR) with redirection of pulmonary venous flow toward the accessory vein draining into the left atrium. (B) Per procedure arteriographic imaging then demonstrated optimal positioning of occluder. (C) Postprocedural 3-month arterial-phase CT scan confirmed satisfactory positioning of the occluder with effective sealing of the PAPVR, no sign of device-related complications, and absence of residual left-to-right shunting. Follow-up assessment using transthoracic echocardiography and contrast-enhanced chest CT confirmed correct device positioning ( Figure 6C ), absence of residual shunt, and no compression or obstruction of adjacent vascular structures ( Figure 7 ). The patient reported marked improvement in dyspnea. In the absence of residual shunting, aspirin was discontinued. Figure 7 Patient 3: Scimitar Syndrome in 34 Years of Age After the Procedure Posterior view of the 3D model from postprocedural cardiac CT result with visualization of the position of the device in green, the right atrium and vena cava in blue, left atrium and fistula in red. Proper correction of the shunt and patency of the fistula to the LA. Patient 3: Scimitar Syndrome in 34 Years of Age After the Procedure Posterior view of the 3D model from postprocedural cardiac CT result with visualization of the position of the device in green, the right atrium and vena cava in blue, left atrium and fistula in red. Proper correction of the shunt and patency of the fistula to the LA.

Scimitar syndrome was first described by Chassinat in 1836. 1 Later, in 1956, Halasz introduced the term “scimitar,” 2 referring to the curved radiographic appearance of the anomalous vein resembling a Turkish sword. In 1960, Neill et al 3 coined the term “scimitar syndrome.” Scimitar syndrome is a rare form of partial anomalous pulmonary venous return, in which one or more right pulmonary veins drain into the IVC, most commonly below the diaphragm. 4 Embryologically, it results from the failure of a normal connection between the pulmonary venous plexus and the common pulmonary vein, with persistence of systemic venous connections. Additional features may include dextrocardia, right-pulmonary-artery hypoplasia, and SA supply to the right lower lobe from the descending aorta. Atypical variants with dual drainage—into both the IVC and the LA—are extremely rare. These variants may preserve a partial physiological pulmonary venous return, potentially delaying the onset of symptoms and enabling alternative, less-invasive management strategies. The estimated incidence of scimitar syndrome is 1 per 100,000 live births, 5 although it is likely underdiagnosed in adults due to nonspecific or asymptomatic presentations. Two clinical forms are traditionally described: an infantile form, characterized by heart failure and respiratory distress, and an adult or late-presenting form, often discovered incidentally during imaging performed for asthma, recurrent infections, or investigation of a left-to-right shunt or sequestration. In our series, all 3 patients presented with the adult-type form, either with exertional dyspnea or incidental radiographic findings. None of them had associated atrial or ventricular septal defects, which are reported in 19% to 30% of cases in published series. Multimodal imaging played a critical role in confirming dual venous drainage in all 3 patients. Cardiac MRI quantified left-to-right shunting (Qp/Qs ranging from 1.3-2.0) and showed right-sided volume overload. Cardiac catheterization provided dynamic hemodynamic assessment, including balloon occlusion testing, which verified the adequacy of venous drainage into the LA and excluded venous hypertension. 6 This step is crucial before proceeding with occlusion of the SV's IVC drainage. It confirms whether the accessory vein can accommodate the full pulmonary venous return, through both angiographic visualization and pressure monitoring. Balloon testing with simultaneous angiography in the right pulmonary artery necessitates dual femoral venous access for optimal assessment. Surgical repair remains the gold standard for most cases of scimitar syndrome, 7 particularly in symptomatic infants or when associated anomalies are present. However, in patients with dual drainage, transcatheter occlusion can be a feasible, safe, and effective alternative. In all 3 cases presented here, the IVC drainage of the SV was successfully occluded using a vascular device. The accessory vein directed venous return to the LA, maintaining a physiological pathway. Particular attention must be given to preserving subhepatic venous drainage before the final device deployment. In addition, 2 patients underwent embolization of systemic collateral arteries supplying sequestrated lung segments. The percutaneous strategy avoided thoracotomy, cardiopulmonary bypass, and the potential complications of open-heart surgery. This series highlights a rare anatomical scimitar variant allowing a percutaneous management. While surgery is standard in classic scimitar syndrome, a dual drainage offers a minimally invasive alternative in selected patients. Our case series is limited by its small sample size and retrospective nature. Long-term follow-up data are currently lacking to evaluate sustained outcomes and device patency. Nonetheless, this report highlights a promising, minimally invasive alternative to surgical correction in anatomically favorable cases. 8 The management of asymptomatic patients without significant left-to-right shunting remains controversial. 9 However, in cases of dual drainage, the physiologic shunt through the fistulous connection to the LA may lead to underestimation of the true shunt burden. Moreover, the cumulative long-term effects of even a moderate shunt may justify early intervention, even in the absence of overt symptoms.

Complete percutaneous repair of scimitar syndrome can currently only be performed in cases of double drainage. This procedure can be performed either before the onset of right-chamber dilation and an increase in Qp/Qs, or at a later stage. Although surgery remains the gold-standard treatment for scimitar syndrome, double drainage with favorable balloon test results may make this less-invasive method preferable. This minimally invasive approach is safe, effective, and allows real-time hemodynamic assessment before definitive occlusion. In patients with associated atrial or ventricular septal defects—which are frequent in scimitar syndrome—simultaneous percutaneous repair may be considered. The long-term management of asymptomatic patients without significant shunt remains an area of debate, but the potential risks of chronic left-to-right shunting should not be underestimated, even in such cases.

Dr Hascoët is proctoring support for Abott, Edwards LifeSciences, and Venus Medtech. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose. Take-Home Messages • Dual drainage of the scimitar vein creates an opportunity for transcatheter repair. • Transcatheter occlusion of the inferior vena cava drainage in dual-drainage scimitar syndrome is safe and feasible when occlusion testing confirms adequate left atrial outflow. • The presence of left atrial drainage reduces the left-to-right shunt and could delay the symptoms apparition. • Dual drainage of the scimitar vein creates an opportunity for transcatheter repair. • Transcatheter occlusion of the inferior vena cava drainage in dual-drainage scimitar syndrome is safe and feasible when occlusion testing confirms adequate left atrial outflow. • The presence of left atrial drainage reduces the left-to-right shunt and could delay the symptoms apparition. Dual drainage of the scimitar vein creates an opportunity for transcatheter repair. Transcatheter occlusion of the inferior vena cava drainage in dual-drainage scimitar syndrome is safe and feasible when occlusion testing confirms adequate left atrial outflow. The presence of left atrial drainage reduces the left-to-right shunt and could delay the symptoms apparition.