Pulmonary Valvular Stenosis

The three main causes of pulmonary valvular stenosis are (Amplatz and Moller 1993): commissural fusion of the pulmonary cusps causing a thickened, dome-like pulmonary valve, bicuspid pulmonary valve and valvular dysplasia. Previously known as trilogy of Fallot, two elements of this trilogy, hypertrophy of the right ventricle and rightto-left shunt through a patent foramen ovale, are the consequences of the pulmonary arterial stenosis (PVS). When the stenosis is limited to the pulmonary valves, and depending on the stenosis intensity, right ventricular systole causes a post-stenotic dilatation of the main pulmonary artery extending in the left main pulmonary artery (Fig. 22.1) due to their common leftward and backward orientation. Elevated pressure leads to muscular hypertrophy of the right ventricle, most marked in the outflow tract. Hypertrophy of the right ventricle leads to counterclockwise rotation of the heart. These changes in the orientation cause the post-stenotic jet to impact primarily on the left main pulmonary artery Open image in new window Fig. 22.1a,b. Typical right ventriculography of a pulmonary valvular stenosis (a). Moderate stenosis of the right ventricular outflow tract. Dome-shaped valvular stenosis with jet phenomenon responsible for the left pulmonary artery dilatation. In another patient, the selective dilatation of the left pulmonary artery is depicted, extending in the proximal part of the left descending PA (b). This acquisition should be performed with cardiac gating and systolic and diastolic short-axis reformations of the valvular apparatus