PHONOCARDIOGRAPHIC STUDY OF VENTRICULAR SEPTAL DEFECT

Abstract

Phonocardiographic studies were made on fifty patients with ventricular septal defect by means of multichannel phonocardiography.The results obtained were as follows.1) The intensity of the apical first heart sound was not increased. The pulmonary second heart sound increased in cases with Eisenmenger's complex, but decreased in cases with tetralogy of Fallot. The splitting of the first and second heart sound was observed in few cases. The diastolic murmur at the apical area was observed in patients with elevated systolic pressure in the right ventricle.2) The intensity ratio of the systolic murmur in ventricular septal defect had wide range of distribution, and it is useful for diagnosis if it is high, but not so much when it is low. Configuration of the systolic murmur was in large majority plateau shape with a peak and it is followed by diamond shape. The pattern in tetralogy of Fallot and Eisenmenger's complex was diamond shape in all cases.3) Relationship to some extent was observed between clinical severity, pulmonary artery pressure, shunt flow, right ventricle pressure, pulmonary vascular resistance and intensity of the systolic murmur, but the intensity of the systolic murmur decreased in severe cases. Continuity of the systolic murmur was holosystolic in severe cases, but it was not holosystolic in most of slight cases.4) The time interval between the onset of QRS of the E.C.G and the onset of the systolic murmur (Q-Mm time) was average 0.094 second in cases with ventricular septal defect, average 0.097 second in cases with tetralogy of Fallot and average 0.09 second in cases with Eisenmenger's complex. Thus it does not exceed 0.10 second, this is a characteristic finding in ventricular septal defect.In the valvular events in the first heart sound, a delay was found in both ventricular elements, but especially in the opening of the pulmonary valve. This shows that, in the ventricular septal defects, both ventricles are loaded, but the loading is higher in the right ventricle. Conclusion was derived that the systolic murmur started before the opening of semilunal valves, i.e., during isometric contraction.