Abstract 16098: Mechanism of Branch Pulmonary Artery Stenosis After the Arterial Switch Operation

Background: Branch pulmonary artery (PA) stenosis, most commonly on the left, is a recognized postoperative complication of the arterial switch operation (ASO) for transposition of the great arteries. We hypothesized that greater rightward rotation of the neopulmonary root and dilation of the ascending aorta are associated with stenosis of the left PA (LPA). Methods: This study represents a retrospective analysis of cardiac magnetic resonance imaging (CMR) studies performed in patients after ASO. Neo-pulmonary root position in relation to the aorta was expressed as an angle, with a negative angle implying a rightward neo-pulmonary root. For the purpose of this study, perfusion imbalance was defined as u003c40% of pulmonary blood flow to the affected lung. The offset between the LPA and right PA (RPA) as a result of cranial displacement of the LPA by asymmetric aortic root dilation was measured in the coronal plane. Results: 74 patients / studies were included for analysis. 73% had no branch PA stenosis, 24% h...