Discussion

The spiral of clinical deterioration observed in some neonates with Ebstein’s anomaly has been attributed to ductal patency and circular shunts. ^{Reference Da Fonseca Da Silva, Devine, Alsaied, Yeh, Lin and Da Silva1–Reference Wald, Adatia, Van Arsdell and Hornberger3} In the absence of anatomic pulmonary obstruction or after relief of outflow obstructions, early limitation of ductal patency ductal was paired with improved survival in neonates with Ebstein’s anomaly. ^{Reference Wald, Adatia, Van Arsdell and Hornberger3} Functional pulmonary atresia happens because the pulmonary blood pressure exceeds the pressure that the small and ineffective functional right ventricle can generate, and the leaflets of the pulmonary valve are unable to open. Therefore, as long as the pulmonary vascular resistance remains high and pulmonary insufficiency remains minimal, systemic oxygenation is maintained through the opened arterial duct and little systemic steal occurs. Yet, when the pulmonary vascular resistance drops, a large arterial duct will jeopardize the diagnosis of functional pulmonary atresia. A large arterial duct will also increase the pulmonary artery pressures, impedes the opening of the pulmonary valve leaflets, and increases the systemic steal. Medically induced pulmonary vasodilation may not always result in the excursion of the pulmonary valve leaflets and the diagnosis will be delayed. In addition, the evaluation of the accurate functional capacity of the right ventricle is very challenging in the presence of systemic pulmonary artery pressures mediated by a large arterial duct. On the other side, in neonates with pulmonary valve insufficiency, ductal patency mediates dangerous circular shunts, leading to intolerable ventricular volume load, significant systemic steal, and haemodynamic instability. In addition, a large left-to-right ductal shunt may compromise cardiac output as increased left atrial pressures limit the right-to-left atrial flow and right-sided decompression.

In all these scenarios, the limitation of ductal patency appears clinically reasonable and beneficial. Transcatheter ductal closure is an appealing minimally invasive straightforward alternative when compared to medical therapy in term neonates or surgical ligation. ^{Reference Kuntz, Staffa and Graham10} However, this percutaneous approach and manipulation can be technically difficult in low birth weight neonates. The relative mismatch of currently available introducers, plugs, or occluders to the small anatomic dimensions makes the effective closure of very large ducts very challenging. The implantation of multiple coils or occlusion devices is risky and can be associated with a higher risk of device embolization. ^{Reference Slaughter, Cua and Notestine5} Others and we have reported spontaneous ductal closure after unsuccessful attempts at transcatheter device closure of arterial ducts in preterm infants. ^{Reference Sathanandam, Gutfinger and O'Brien7–Reference Deniwar, Brown and Balaguru9} Here, we report, for the first time, the same event in two consecutive term newborns with Ebstein’s anomaly. Congenital interventionists are also familiar with different degrees of temporary ductal spasms secondary to mechanical stimulation during cardiac catheterizations. ^{Reference Batlivala, Glatz, Gillespie, Dori and Rome11,Reference De Decker, Comitis, Thomas, van der Merwe and Lawrenson12} However, in these two term newborns, we did not observe ductal spasms or changes in the ductal size whether during manipulation or at the end of the procedure and the postoperative ductal closure was permanent without any evidence of recanalization during follow-up. It appears that mechanical stimulation of the ductal inner wall from transcatheter wire/device manipulation and/or the acute stretch provoked by the occluder deployment within the lumen may initiate the process of spontaneous ductal closure even in term neonates. Therefore, a watchful observation for a minimum of 48 hours after a failed closure procedure might avoid surgical ligation of the arterial duct and related morbidity and complications. ^{Reference Méot, Haddad and Patkai8,Reference Deniwar, Brown and Balaguru9}