PM1006: Isolated Pulmonary Artery of Ductal Origin: A Clinical Challenge!

Introduction: Isolated Pulmonary Artery of Ductal Origin (IPADO) refers to the anomalous origin of one of the branch PAs from the ductus arteriosus. Although rare, it has been reported in the literature with early staged intervention found to be associated with good clinical outcome. Our patient underwent successful ductal stenting relatively early but developed rapidly progressive, medically unresponsive, severe pulmonary hypertension making him a high-risk surgical candidate and raising a clinical challenge.

Case Description: A one-month-old, ex-34-week male with 22q11 deletion was transferred to our facility due to persistent desaturations. Echocardiogram showed a large membranous ventricular septal defect with left-to-right shunting, normal sized left pulmonary artery (LPA) arising from the main pulmonary artery (MPA) but an absent right pulmonary artery (RPA), and no patent ductus arteriosus (PDA). Cardiac catheterization confirmed the absence of RPA (Figure 1) with no evidence of flow to the right-sided pulmonary circulation and a nearly occluded PDA arising from the right brachiocephalic artery. A normal left-sided capillary blush on wedge angiogram suggested absence of significant pulmonary vascular disease. The PDA failed to open with a trial of high dose prostaglandin-E and was stented with follow-up angiogram confirming excellent flow to the entire right-sided pulmonary circulation (Figure 2). Post-cath course was uncomplicated and the patient was discharged on dual antiplatelet therapy and diuretics. Initial 2- and 4-week follow-ups showed clinical and echocardiographic stability, however by 8 weeks, there were signs of right ventricular hypertension, progressive right ventricular hypertrophy, and predominantly right-to-left shunting across the VSD. Repeat cath confirmed progressive pulmonary vascular disease with poor capillary blush and pruning on wedge angiogram. Pulmonary vascular indices showed no improvement with hyperoxia or nitric oxide. Given the rapid progression and severity of the disease, he was considered a high-risk surgical candidate and was managed medically with dual pulmonary vasodilator therapy. He ultimately underwent unifocalization at 5 months of age and is clinically stable at this time.

Discussion: In cases of IPADO, closure of the ductus directs the entire pulmonary blood flow to the contralateral lung, resulting in progressive pulmonary vascular disease of that lung and maldevelopment of the ipsilateral organ. Pulmonary hypertension of the contralateral (normally connected) lung after PA stenting has also been reported with a significant increase in incidence with concurrent intracardiac shunts. Although improvement of pulmonary hypertension after unifocalization has been demonstrated, the severity of our patient’s pulmonary hypertension and unresponsiveness to medical management placed him at a high surgical risk.

Conclusion: Despite early revascularization, IPADO can present as a challenge due to rapid progression of pulmonary vascular disease in the contralateral normal lung. This complication must be considered during prognostic discussions with families.