Further morphologic studies on hearts with pulmonary atresia and intact ventricular septum

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Abstract
Summary: Atresia of the outflow tract of the right ventricle in the presence of an intact ventricular septum poses major problems for surgical management. In the light of known problems, 43 autopsied hearts with this congenital abnormality were evaluated to note the arrangement of the myocardium and the cavity of the right ventricle, the state of the tricuspid valve, the precise substrate for pulmonary atresia, and the presence offistulous communications between the ventricular cavity and the coronary arteries. The specimens could be divided into two groups. The first group (38 hearts) had hypoplasia of the cavity of the right ventricle with mural hypertrophy while the second group (5 hearts) had a dilated right ventricular cavity with thinning of the wall. The larger group could be divided into two subgroups on the basis of the substrate for pulmonary atresia. Twenty hearts had muscular atresia of the right ventricular outflow tract and 18 had a potentially patent outflow tract blocked by an imperforate pulmonary valve. A comparison of these two subgroups revealed that mural hypertrophy and cavitary hypoplasia were more severe in hearts with muscular atresia. The tricuspid valve was hypoplastic and its leaflets were not dysplastic in this group but the leaflets were dysplastic in hearts with valvar pulmonary atresia. Fistulous communications between the ventricular cavity and the coronary arteries were only seen in the cases with muscular atresia. In this series, recognition of muscular pulmonary atresia would have identified those patients with the worst surgical prognosis.