Phonocardiographic analysis of diastolic flow murmurs in secundum atrial septal defect and ventricular septal defect.

Abstract

Diastolic flow murmurs in 20 patients with secundum atrial septal defects and 20 patients with uncomplicated ventricular septal defects were analyzed from phonocardiographic tracings. The onset of the "flow rumble" in the patients with atrial septal defect was found to occur 0.03 to 0.07 sec. (mean = 0.05 sec.) after the pulmonary component of the second sound (P2), while that in the patients with ventricular septal defect was 0.07 to 0.15 sec. (mean = 0.10 sec.) after P2. The difference of the means is statistically significant (p< 0.001). The relative earliness of the murmur in atrial septal defect is partially an ausculatory illusion; the delayed pulmonary second sound, usually found in these patients, makes the onset of the murmur appear earlier. Nevertheless, this short interval is useful clinically and can usually be discerned at the bedside. The separation of flow murmurs from other diastolic murmurs (representing semilunar valve incompetence, associated mitral valve disease, etc.) in patients with atrial and ventricular septal defects is discussed. Since flow rumbles may occur in early diastole, it is suggested that in the differential diagnosis of diastolic murmurs in these patients, characteristics other than the timing of the murmur be used to determine the etiology.