Discussion

Bilateral arterial duct is a very rare anomaly, presumably due to maldevelopment of the sixth aortic arch during early embryogenesis. It has been more frequently described in pulmonary atresia, usually with non-confluent pulmonary arteries, with a high association with heterotaxy syndrome. ^{Reference Peirone, Abdullah, Dicke, Freedom and Smallhorn1} It has been more rarely reported in the setting of other complex CHDs such as hypoplastic left heart syndrome. ^{Reference Gray, Sorabella, Berry, Padilla, Law and Dabal2} In pulmonary atresia with ventricular septal defect, non-confluent pulmonary arteries, and in the absence of major aorto-pulmonary collateral artery, each branch pulmonary artery is supplied independently by its ipsilateral ductus arteriosus, as seen in our case. Isolation of the pulmonary artery may occur early within the first days of life, or later on up to 12 months of age. ^{Reference Waldman, Karp, Gittenberger-de Groot, Agarwala and Glagov3} Early neonatal physiologic ductal closure may result in abrupt pulmonary hypoperfusion and life-threatening hypoxia, thereby prompting emergent intervention. Surgical management has been applied successfully, consisting in either bilateral modified Blalock–Taussig shunt or unifocalisation of the non-confluent pulmonary arteries under cardiopulmonary bypass. ^{Reference Nakamura, Kanno and Nishioka4,Reference Stamm, Friehs and Zurakowski5} Both surgical strategies are challenging, especially in low-birth-weight infants, and may result in pulmonary arteries distortion and decreased long-term patency due to excessive tension on surgical anastomoses. ^{Reference Stamm, Friehs and Zurakowski5} Ductal stenting carries a < 1% procedure-related mortality rate but a 9%–13% complication rate in the current era, with reported major acute (ductal spasm, stent malposition or embolisation, and acute stent thrombosis) and late (pulmonary overflow and neointimal proliferation) complications. ^{Reference Valdeomillos, Jalal, Boudjemline and Thambo6} Because of their flexibility and low profile, we used balloon-expandable coronary stents with favourable results and long-term patency of both pulmonary arteries. Ductal stenting in duct-dependent pulmonary circulation has however become widely accepted as a safe and efficient alternative to surgery, carrying a lower risk of postprocedural complications, extracorporeal membrane oxygenation (ECMO) use or mortality, as well as higher postprocedural oxygen saturation and Nakata index as compared to modified Blalock–Taussig shunt; ^{Reference Abdelmassih, Menshawey and Menshawey7} it has also been shown to be effective in promoting a significant catch-up growth of duct-dependent discontinuous pulmonary arteries. ^{Reference Santoro, Capozzi and Giordano8} The benefits-to-risks ratio for ductal stenting has been shown to be less favourable in infants with a tortuous ductus, a body weight< 2.5 kg, and/or an insufficiently constricted ductus. ^{Reference Alwi and Mood9} High success rates have been achieved in experienced hands, and in a recent report of 38 ductal stenting in low-body-weight infants with duct-dependent pulmonary circulation, Al Nasef et al. showed that ductal stenting is feasible and effective in neonates < 2.5 kg, promoting adequate pulmonary artery growth. ^{Reference Nasef, Shahbah and Batlivala10} Reintervention rates are relatively high in this weight group, though many are planned to allow for optimal pulmonary artery growth before a definitive operation. According to ductal origin, ductal morphology, and ductal length, various techniques and vascular approaches may be considered. In tetralogy of Fallot with pulmonary atresia, the ductal morphology is often complex and ductal stenting is usually performed via an antegrade approach through the femoral vein, or a retrograde route via the femoral artery, or even via a common carotid or axillary artery surgical cut-down.