Pulmonic Stenosis, Ventricular Septal Defect, and Right Ventricular Pressure above Systemic Level

Ten patients with pulmonic stenosis are reported who, despite having right ventricular systolic pressures much above systemic levels, had ventricular septal defects proved at operation in 9 and suggested by indicator-dilution curves in the other. Because of the high right ventricular systolic pressures these patients had clinical and electrocardiographic evidence of marked right ventricular hypertrophy and were initially thought to have severe pulmonic stenosis with an intact ventricular septum. One patient had an almost single ventricle with pulmonic and aortic stenosis. In all the others the right ventricular systolic pressure failed to equilibrate with pressures in the systemic circulation. In 2 patients this was probably due to obstruction of the ventricular septal defect by the septal leaflet of the tricuspid valve. In the others the suggestion that the ventricular septal defect was closed off during systole by muscular contraction was confirmed in 1 patient at operation. This syndrome has been reported in other series and may occur in as many as 5 to 10 per cent of patients diagnosed as having severe pulmonic stenosis. It is important to know before operation whether or not there is a ventricular septal defect associated with the pulmonic stenosis, for this influences the decision about doing a right ventriculotomy. The preoperative diagnosis of this variant of tetralogy of Fallot may be made by phonocardiography and cardiac catheterization.