Ventricular pressure flow relationships in isolated valvular stenosis.

The obstruction to the outflow of blood from the right ventricle in pulmonary stenosis has, in the past, been considered largely in terms of pressure gradients recorded between the pulmonary artery and right ventricle during cardiac catheterization and surgical operations, or of the degree of stenosis demonstrated by angiocardiography and autopsy. More recently it has been recognized that muscular hypertrophy is responsible for the infundibular stenosis so often seen in severe cases of pulmonary valvular stenosis, and this has led to more critical appraisal of pressure flow relationships in the right ventricle.