Intensity Distribution of the Systolic Murmur in Ventricular Septal Defect on the Chest Surface

Publisher Website
Google Scholar
Abstract
The intensity distribution of systolic murmur on chest surface was examined on 7 patients with ventricular septal defect. The frequencies of 79, 100, 200, 400 and 800 cps were investigated. On the chest surface the equal intensity contour lines of the systolic murmur in ventricular septal defect were of approximately concentric circles centering around the point of maximum intensity of the murmur for each frequency. On the frequencies of 79, 100, 200 and 400 cps, the relationships between the relative intensity in decibels [dB] of the murmur and the distance from the point of maximum intensity of the murmur were inversely proportional. The apparent dampings/cm of distance were from 0.4-1.8 dB/cm for 100 cps, 0.4-2.0 dB/cm and from 0.7-3.3 dB/cm for 400 cps. On the frequency of 800 cps, the apparent damping becomes smaller according as the distance from the point of maximum intensity increased, in 4 of 7 cases. The apparent viscous damping obtained from the present data was generally smaller than the viscous damping of the sound during the transmission over chest surface.