Severe Subaortic Stenosis in Interrupted Aortic Arch in Infancy and Childhood

Abstract

Thirteen out of a total 50 infants with interrupted aortic arch (IAA) seen between 1979-1988 had or developed severe subaortic stenosis (SAS). One had type A interruption and 12 type B. All had a large ventricular septal defect (VSD). The infundibular septum was displaced posteriorly in eight infants, severely narrowing the left ventricular outflow tract (LVOT). Three had fibromuscular narrowing of the LVOT, one each a subaortic muscle bar and membrane. The aortic root and subaortic area were small and measured between 3-8 mm. An anomalous right subclavian artery was noted in eight of the 12 type B IAA, the anomalous vessel arising from the descending aorta in seven. Thirteen infants with IAA and SAS were submitted to surgery, 12 having their subaortic area resected with three perioperative deaths early in the series and three late deaths where active treatment was ceased, including one infant with renal dysplasia who had had a successful establishment of arch continuity and pulmonary artery banding. Of the seven survivors, six have residual Doppler gradients of between 20-50 mmHg, two requiring a second resection and one a third resection. Alternate management programs are suggested based on anatomical evaluation and echocardiography. Any newborn presenting with IAA requires careful evaluation of the subaortic area, best seen on cross-sectional echocardiography. The improved surgical survival in infants following complete repair of IAA has led this important associated anomaly of subaortic stenosis to assume greater importance as a cause of mortality and long-term morbidity.