Obstruction of left ventricular outlet in association with ventricular septal defect.

A VENTRICULAR septal defect either as an isolated malformation or as part of nmany developmental complexes is the most common single developmental lesion of the heart. In an overwhelming percentage of cases, hearts bearing a ventricular septal defect whether or not other conditions are associated have no additional intracardiae lesion that causes obstruction to the normal egress of blood from the left ventricle. In a pathologic collection of 722 hearts bearing malformations, we have observed 10 cases in which a ventricular septal defect was associated with obstruction of the left ventricular outlet. The purpose of this communication is to describe the varied anatomic arrangements encountered in these 10 cases and to report on their clinical features as well as the objective functional studies, when done. One additional case that was observed clinically and at operation -is also reported. This is done since it serves to make more nearly complete the classification of those anatomic arrangements in which the common denominators are ventricular septal defect and obstruetion to left ventricular outlet. The hemodynamic derangements that obstruction of the left ventricular outlet adds to a ventrieular septal defect depend on the anatomic interrelationship between the ventricular septal defect and the site of obstruction and on the size of the defect itself. When the defect is large, the factor that determines the pressures in the chambers of the heart and the systemic circulation is the position of ob-