Leaving the Ductus Open During BTT Shunt: Risk of Ductus-Associated Pulmonary Coarctation?

I have read with great interest the manuscript by Nasworthy et al ¹ which described a retrospective comparative cohort research study involving 36 infants receiving Blalock-Taussig-Thomas (BTT) shunt surgery and assessing the influence of ligated or left open ductus arteriosus on postoperative outcomes. They concluded that leaving the ductus arteriosus open provides a potential rescue option without increasing the risk of postoperative low cardiac output, and that ductus arteriosus management during shunt insertion had no effect on outcomes. I have some remarks and questions.

First, Infants who have had a BTT shunt have a variety of morphologic abnormalities, each with their own pathophysiology and perioperative behavior, as well as different levels of preoperative oxygen saturation both before and after prostaglandin infusion. Do the authors have any comments on morphologic differences, preoperative oxygen saturations, and prostaglandin response?

Second, while it appears that leaving the ductus arteriosus open as a potential rescue treatment in the event of a postoperative emergency is a safe method in the short term, I have concerns regarding the developement of the pulmonary arterial tree in the long term. Because those patients will undergo additional surgeries, having a well-developed pulmonary arterial tree is critical, regardless of whether the surgical approach is univentricular or biventricular. It has previously been demonstrated that there can be ductal tissue in a stenosed section of the pulmonary artery (PA) following physiologic ductal closure, and there is a high incidence of ductus-related PA stenosis in individuals with pulmonary valve atresia/stenosis. ² It has also been shown that ductal-associated PA coarctation is more common in patients with pulmonary atresia than in those with pulmonary stenosis, and can occur in up to 60% of patients with pulmonary atresia. ³ It is evident that if late stenosis or atresia develops at this location, subsequent procedures are made more difficult, particularly in the event of univentricular circulation, because of the higher pulmonary vascular resistance. As a result, some centers recommend vigorous reconstruction of the infant's central pulmonary artery which includes ligating the ductus arteriosus at the time of BTT shunt . ⁴ I would like to know if the authors have seen any ductal coarctation after BTT shunt in patients where the ductus arteriosus was left open.

I applaud the authors for their findings, but I would emphasize the necessity of making decisions that are adapted to the unique infant's anatomic morphology taking into account the long-term development of the pulmonary arterial vasculature.