The graphic configuration of innocent systolic murmurs.

The systolic murmurs heard in healthy subjects used to be called " functional " murmurs. White et al. (1942) recommended the term " physiologic." Evans (1947) called these murmurs " innocent." Others have called them " incidental,' "' accidental,'' or "' murmurs of unknown origin." The decision that a systolic murmur is innocent usually depends not only on the character of the murmur itself, but also on the absence of any evidence of organic heart disease. The improvement in the technique of phonocardiography during the last decade provides a means whereby the innocent systolic murmurs can be studied more objectively. Such a study should lead to more accurate diagnosis, to a more useful classification, and perhaps to an explanation of the production of these murmurs. Bass et al. (1933) found that innocent systolic murmurs were composed only of high-frequency vibrations and this differentiated them from organic murmurs which were composed of both lowand high-frequency vibrations. Evans (1948) clearly demonstrated the brief duration of innocent systolic murmurs by phonocardiography, and later (1951) he stated that " A detection of the frequency of the separate murmurs may also contribute to a readier recognition of the innocent ones from amongst the others." Evans (1948) also described the phonocardiogram of the late systolic murmur. Harris et al. (1949) studied the phonocardiogram of children with mitral regurgitation and children with innocent systolic murmurs; they described the short duration and " vibratory " nature of the innocent murmur, and noted the similarity of pattern to that produced by a tuning fork. Harris and Friedman (1952) collected 28 tracings of " vibratory" systolic murmurs in children, and Boldrini et al. (1954) added a further 20 tracings. The latter workers found the duration of the murmur was between 0-07 and 0-12 seconds. Other workers (Wood, 1950; Gmachl, 1953; and Wells, 1954) have published tracings of innocent systolic murmurs. The object ofthe present study is to describe the appearance on the phonocardiogram ofinnocent systolic murmurs. The appearance should be of value in the diagnosis and explanation of innocent systolic murmurs, and should help in the differentiation of such murmurs from the murmurs of organic heart disease.