Intracardiac phonocardiogram in thirty cases of atrial septal defect.

Thirty cases of atrial septal defect proved by cardiac catheterization, surgery, or post-morten examination have been investigated with the technic of intracardiac phonocar-diography, which provided precise localization of the source of heart sounds and murmurs. The site and mechanism of origin of the many auscultatory signs in uncomplicated atrial septal defect and in cases of Lutembacher's syndrome, tricuspid atresia, and persistent atrioventricular canal were elucidated by direct intracardiac sound recordings and simultaneous external chest phonocardiograms. THERE have been many recent reports of the auscultatory features of atrial septal defect and these have been reviewed both clinically and with the aid of chest phono-cardiography.1-7 The commonest auscultatory findings in uncomplicated atrial septal defect are a basal systolic ejection murmur, usually soft, and a wide, fixed splitting of the second sound over the pulmonary area. Less frequently an early blowing diastolic murmur is heard at the base and along the left sternal border iii the second and third left intercostal spaces. At the apex, or medial to it, systolic and dias-tolic murmurs may occasionally be present, together with an accentuated first sound. The systolic apical murmur is usually of regurgitant type (pansystolic) ; the diastolic apical murmur occurs in mid-diastole or in presystole. There appears to be no general agreement about the site and mechanism of production of these signs. The relative importance of various factors such as the flow across the atrial septal defect, the increased flow through the tricuspid and pulmonary valves, and the anatomic changes in the mitral and tricuspid valves, has not been established with certainty. The purpose of this study was to contribute to a better understanding of the site and mechanism of production of the altered heart sounds and murmurs in atrial septal defect with the help of intracardiac sound recording. The technic originally described by Liewis et al.8 for intracardiae phonocardiography has been used. Precise localization of the sources of sounds and murmurs is possible with the aid of a barium titanate microphone incorporated in the leading tip of a specially designed catheter. Some intracardiac phono-cardiograms by this and other technics in cases of atrial septal defect have been reported .9-'2 MATERIAL AND METHODS Thirty cases of proved atrial septal defect are included in this study: 18 were male and 12 female, and they ranged in age from 3 to 54 years, the majority being in the second and third decade of life. The diagnosis …