Study by cathode-ray oscillography of some innocent and pathologic cardiac murmurs of children

Abstract

Cardiac murmurs of several types found in children and adolescents have been recorded on magnetic tape and examined by cathode-ray oscillography. The types of murmurs studied have included two presumably innocent types of murmurs, the precordial vibratory (“twanging-string” murmur of Still) and the pulmonic-systolic murmur, which comprise the great majority of nonpathologic murmurs of childhood, and several types of organic murmurs, those due to aortic and mitral insufficiency and to a variety of congenital malformations. In terms of wave form, the precordial vibratory murmurs examined showed a discernible basic wave of frequency ranging from 90 to 180 cycles per second, among various subjects, with a small and variable degree of distortion. In oscillograms of pulmonic-systolic murmurs a basic wave in the range of frequency given above could also be discerned, but the degree of distortion was noticeably greater than that found in the precordial vibratory murmurs. In the case of the specimens examined in all the groups of organic murmurs mentioned above the wave forms were highly complex, with no detectable basic wave or recognizable pattern. A possible implication of these differences in wave form is discussed.