Comparison of left ventricular outflow tract obstruction in interruption of the aortic arch and in coarctation of the aorta, with diagnostic, developmental, and surgical implications.

A morphometric comparison of the anatomic causes of left ventricular (LV) outflow obstruction in interruption of the aortic arch and in coarctation of the aorta with ventricular septal defect (VSD), based on 30 postmortem cases of each, revealed that posterior malalignment of the conal septum with a conoventricular VSD was significantly more prevalent with interruption (93%) than with coarctation (47%) (p <0.001). The ratio of the aortic valve diameter-to-the pulmonary valve diameter, which provided a quantitative index of the degree of posterior conal septal malalignment and of the consequent LV outflow tract obstruction at and immediately below the level of the aortic valve, was significantly smaller with interruption (