Major VASCULAR surgery in which the heart is not directly attacked can be performed with a minimum of operative risk. In our opinion the reason for this is that the heart is capable of maintaining its full function throughout the period of surgical manipulation.
Performance of closed direct intracardiac surgery for such congenital conditions as pulmonic stenosis and atrial septal defect and for such acquired lesions can be accomplished with a low operative mortality, although the heart is forced to maintain its circulatory function both during and after the definitive surgery. However, it will be noted that each of these conditions is deleterious to the heart primarily because of overwork and strain of the right ventricle. Functionally, each of these conditions is a "rightsided" cardiac lesion. In each the left ventricle is spared by the disease, "protected" against overwork by the lesion itself. In fact, the left ventricle actually may