The tricuspid valve in pulmonary atresia and intact ventricular septum: a morphological study of 60 cases.

A morphologic study of the tricuspid valve was performed in 70 patients with pulmonary atresia and intact ventricular septum who had died and subsequently undergone autopsy. The right ventricular cavity was enlarged in 8 patients, normal in 4 patients, mildly underdeveloped in 18 patients, and markedly underdeveloped in 24 patients. In the patients with dilated and enlarged right ventricle, the tricuspid valve exhibited features of dysplasia or Ebstein's malformation (downward displacement), or both, with a dilated anulus. The majority of patients had restriction of the tricuspid valve apparatus and an underdeveloped anulus, usually of a severe degree. The right ventricle appeared to have normal dimensions in four patients, but the tricuspid valve and tensor apparatus, even in these patients, exhibited departures from the normal. This study suggests that in many of these patients adequate right ventricular growth will not be achieved because of inadequate right ventricular filling. This seems directly related to moderate or severe underdevelopment of the tricuspid valve.