“…Intracardiac phonocardiography has provided support for the theory that the diastolic "flow rumble" of atrial septal defect originates at the tricuspid valve and that of ventricular septal defect at the mitral valve (Liu and Jacono, 1958;Feruglio and Sreenivasan, 1959;Feruglio and Gunton, 1960). It is commonly accepted that the presence of a "flow rumble" indicates a rather large left-to-right shunt (Wood, Magidson, and Wilson, 1954;Leatham and Segal, 1962;Segal, Novack, and Kasparian, 1964).…”