Melbourne Shunt Promotes Growth of Diminutive Central Pulmonary Arteries in Patients With Pulmonary Atresia, Ventricular Septal Defect, and Systemic-to-Pulmonary Collateral Arteries

Background: We manage patients with pulmonary atresia, ventricular septal defect, major systemic-to-pulmonary collateral arteries, and diminutive central pulmonary arteries with a staged approach. The first procedure is a central end-to-side aortopulmonary shunt (Melbourne shunt) intended to cause growth and development of the central pulmonary arteries. We subsequently measured central pulmonary artery growth after Melbourne shunt. Methods: Forty consecutive patients were followed after Melbourne shunt. The maximum pulmonary artery diameter was measured at the time of surgery and at subsequent catheterizations or surgery. Results: Median pulmonary artery size at surgery was 2 mm. The median pulmonary artery diameter was 5.5 mm at first assessment (median, 6.35 months) and 7 mm at most recent assessment (19.7 months). Mean modified Nakata index increased from 27 mm²/m² at surgery to 138 mm²/m² at first assessment, and 176 mm²/m² at final assessment. There was one acute shunt failure from anastomotic stenosis. Thirteen patients (32.5%) required 21 percutaneous interventions. There were 4 deaths during a median follow-up of 68 months. At the time of complete repair (n = 25) all patients required pulmonary artery augmentation, and 8 are in various stages of palliation. The remaining patients are considered not reparable owing to irreversible pulmonary hypertension (n = 4) or have required fenestration of ventricular septal defect after complete repair (n = 2). Conclusions: Melbourne shunt promotes modest growth of central pulmonary arteries leading to complete repair in the majority of patients. There is considerable need for further interventions in these patients to augment the size of the pulmonary arteries.