The pericardial tunnel technique might produce optimal morphological repair of the scimitar syndrome.

The scimitar syndrome is a rare congenital heart defect that continues to pose a management challenge, especially in patients requiring surgery during infancy [1–3]. The sine qua non is the presence of anomalous connection of the right pulmonary veins to the inferior vena cava (IVC), commonly in association with atrial septal defect. Concomitant anomalies, such as dextrocardia, right lung hypoplasia and anomalous systemic arterial supply to the right lung, are often present and contribute to clinical presentation and recovery [1–3]. Several surgical techniques have been described to repair scimitar syndrome. The traditional approach involves intracardiac baffling between the anomalous vein and the left atrium through the atrial septal defect, with IVC patch augmentation [1–4]. Outcomes of intracardiac baffling have been disappointing, especially in infants, with high incidence of pulmonary venous obstruction (PVO) or IVC stenosis. Several anatomical factors contribute to PVO or baffle thrombosis including native pulmonary vein orifice stenosis (in 25% patients), the acute angle that blood takes as it traverses the baffle into the left atrium and baffle patch shrinkage. Consequently, surgeons explored alternative procedures to avoid the shortcomings of intracardiac baffling, mostly aiming to provide direct pathway of the right pulmonary veins to the left atrium, by reimplanting the right pulmonary vein to the left atrium or the posterolateral wall of right atrium, in combination with simple atrial septum reconstruction [2, 3, 5, 6]. While those eliminated the long, complex, angulated pathway associated with the intracardiac baffling, the reported PVO incidence has also been high, likely due to pulmonary vein distortion or anastomotic stricture [2, 3, 5, 6]. A recent series from Boston described PVO incidence of 46% with intracardiac baffling and 63% with reimplantation procedures [2]. This PVO incidence mimics that following total anomalous pulmonary venous connection repair, also due to pulmonary vein distortion or anastomotic stricture [7]. The sutureless pericardial well technique improved repair outcomes in patients with PVO following total anomalous pulmonary venous connection repair. The obstructed pulmonary veins are widely opened, and the pericardium is folded and sutured to create a pericardial tunnel (neoatrium) that connects the opened veins to a large left atrial opening, thus avoiding pulmonary vein distortion and suture line stricture. Lugones et al. [8, 9] from Buenos Aires described an innovative scimitar repair strategy using the sutureless repair concept. The right pulmonary vein is disconnected off the IVC, opened and connected widely to the adjacent right pericardium; a wide opening in the left atrium is created and finally, the pericardium is folded connecting the 2 openings and creating neoatrium made of the pericardial tunnel. Their initial experience though was limited to few patients and did not include infants [8, 9]. This strategy is attractive as it addresses several drawbacks that increase PVO risk in the other techniques. The pathway between the right pulmonary veins and the left atrium is straightforward, native pulmonary vein orifice stenosis is irrelevant, interposition prosthetic material is not used and issues of patch shrinkage, pulmonary vein distortion or anastomotic strictures are minimized. Finally, surgery can be performed without circulatory arrest need, and IVC stenosis risk is eliminated. However, potential shortcomings can include bleeding due to tissue friability (the pericardium and scimitar vein), especially in infants, phrenic nerve injury, PVO due to inadequate openings on the vein, pericardium or left atrium or insufficient pericardial flap. In the current issue of the journal, Sun et al. [10] from Shanghai report their experience with the pericardial tunnel technique in 9 children, including 5 infants. They had no mortality, major complications or PVO. This report is valuable as it validates the Lugones technique in a larger series, confirms the low incidence of technical complications despite the learning curve and proves the utility of this technique in infants despite notional concerns about tissue friability. The authors favour this technique in patients in whom the scimitar vein joins the IVC at an angle <_45 and share their experience and thoughts on how to avoid several pitfalls of this surgery. In summary, the pericardial tunnel repair strategy for scimitar syndrome might provide the optimal morphological product that neutralizes many of the anatomical factors instigating PVO C O N G EN IT A L