Physiologic Differentiation of Pulmonic Stenosis with and without an Intact Ventricular Septum

W ITH THE advent of open-heart sur-gery it has become more than ever iin-portailt to differentiate between pulmonic stenosis with an intact ventricular septumn (designated as pulmonic stenosis) and pul-monic stenosis with a right-to-left shunt through a ventricular septal defect (tetralogy of Fallot) because of their different operative treatment and operative mortality. Failure to close an associated ventricular septal de-fect after completely relieving the obstruction to right ventricular outflow may produce a large left-to-right shunt and bring on conges-tive heart failure;1-3 if enough obstruction remains, there may be no or little left-to-right shunt but the treatment cannot then be con-sidered ideal.2 Unfortunately, attempts to detect the ven-tricular septal defect at operation by passing a finger down through the pulmonary valve or by looking for an immediate left-to-right shunt into the right ventricle may be unsuc-cessful. The alternative of performing rou-tine right ventriculotomy would disclose un-suspected ventricular septal defects but has the disadvantage that it could lead to com-plications like hemorrhage, ventricular rup-ture,3 or ventricular aneurysm. ' An accurate anatonmie diagnosis preoperatively is there-fore very important and this may usually be done by routine clinical and radiologic exam-ination and electrocardiography.4-7 There are times, however, when these studies are not adequate to make a definite diagnosis; the