The Narrow Infundibulum in Pulmonary Valvular Stenosis

OBSTRUCTION to the outflow of blood from the right ventricle may occur as a result of congenital stenosis of the pulmonary valve, of the infundibulum, or of the supravalvular area. These all result in a fixed constriction of the lumen of the involved region. Recently, considerable interest has been focused upon a more dynamic type of infundibular obstruction that occurs in a number of patients with valvular pulmonic stenosis and an intact ventricular septum. This narrowing becomes most prominent durinog systole, and is due to hypertrophy of the wall of the right ventricle in the area of its outflow tract. Although some controversy exists as to the importance of this phenomenon, there is evidence that it may occasionally become quite significant if it is not recognized preoperatively and corrected at the time of surgery on the valve. The purpose of the present paper is to analyze the outflow tract of the right ventricle as studied by routine angiocardiography, and to establish criteria that indicate the presence of an abnormally narrowed infundibulum in patients with pulmonary valvular stenosis and an intact ventricular septum.