Unilateral Branch Pulmonary Artery Origin From a Solitary Arterial Trunk With Major Aortopulmonary Collaterals to the Contralateral Lung: Anatomic and Developmental Considerations.

In both truncus arteriosus communis (TAC) and tetralogy of Fallot (TOF), there is a rare phenotype that includes a single branch pulmonary artery (PA) arising from a solitary great artery and major aortopulmonary collaterals (MAPCAs) supplying the contralateral lung. We describe the intracardiac and great vessel anatomy of infants with this phenotype, consider rationale for classifying patients as TOF vs TAC, and describe surgical outcomes. Our institution's surgical database was reviewed for patients with a single branch PA from a solitary arterial trunk and contralateral MAPCAs from 2007 to 2019. Demographic, imaging, and surgical data were collected and described. All 11 patients underwent complete repair with a median right ventricular to aortic pressure ratio of 0.36 (range 0.26-0.50). At 0.1-9.1 years after repair (median 0.8 years) there was approximately balanced left-right lung perfusion (median 52% to the right lung, range 34-74%). The MAPCA lungs exemplified the full spectrum of PA and MAPCA anatomy, from absent intrapericardial PAs with all single supply MAPCAs to a normally arborizing PA with all dual supply MAPCAs and present pulmonary valve leaflet tissue. All patients had a systemic semilunar valve with 3 thin and similarly sized leaflets and fibrous continuity with the tricuspid valve, and all had coronary origins and outflow tract morphology more consistent with TOF. It is appropriate to classify all patients with a single anomalous PA from a solitary arterial trunk and MAPCAs to the contralateral lung as TOF rather than TAC Type A3. All variants were amenable to surgical repair.