The Apical First Heart Sound as an Aid in the Diagnosis of Atrial Septal Defect

Abstract

The phonocardiograms of 187 patients were reviewed. In 89 the apical first heart sound was soft or single; in 57 M ₁ was louder than T ₁ and in 23 the two components were equal. In only 18 cases was T ₁ louder than M ₁ at the mitral area, and of this group five were suspected of having atrial septal defect and 10 were proved cases. In three of the proved cases, this was the only significant finding, the other usual features being absent. Only two proved cases of atrial septal defect in this series did not have T ₁ louder than M ₁ at the apex; both had T ₁ equal to M ₁ . One case suspected of having atrial septal defect also had T ₁ equal to M ₁ and in another suspected case the first heart sound was single. This unusual characteristic of the first heart sound may be useful as an indication favoring the diagnosis of uncomplicated atrial septal defect.