Studies of Heart Sounds by Frequency Band Recoridings of Mingograph.

Abstract

By recording heart sounds and murmurs of 102 cases from mitral valve disease and functional murmur groups in frequency bands of 12.5, 25, 50,100,200, and, 400c/sec. by mingograph, phonocardiographic studies were carried out. The results are as follows : 1) In the mitral stenosis group, loud and high frequency components in the first heart sound were evident when compared to the second sound. The ratio of thd greatest amplitude of the first and second sounds was significant for a differentiation from steno-insufficieny group. The systolic murmurs in mitral steno-insuffiency cases were not recorded satisfactory from channel 4 (100c/sec) and over. Good recordings of diastolic murmurs were obtained in the low frequency bands in both groups, but above channel 4 poor recordings were also seen. The channels 2 and 3, i.e. 25 to 50c/sec showed a most clear characteristic picture of both groups, but the presystolic murmurs showed a tendency to appear in a some what higher freqnency bands. 2) The diastolic murmurs of aortic insufficiency were recorded satisfactory up to the high frequency bands and its characteristic forms were most clearly seen in channels 3 and 4 (50 to 100 c/sec). 3) The second sounds of the congenital heart disease group all showed loud and high frequency components, but this was most evidedt in A.S.D. All types of congenital cases showed a similar tendency of possesing compoents of relattively high frequency in systolic murmurs when compared to the first sound. The durations of murmurs were long in V.S.D. and Eisenmeger type and short in A.S.D. and pulmonary stenosis. 4) Functional systolic murmurs were soft and short and their frequency were low. A rapid reduction of satisfactory recording were seen over channel 4 (100c/sec).