This article reports on the application of an automatic tape-recording unit to the case-finding of children with heart disease. Field studies with this apparatus have been carried out among the elementary school population in Chicago. The incidence of heart disease in school-age children in the United States is approximately 5% according to several investigators.
Since almost all heart disease in children is associated with the production of cardiac murmurs or alteration of the cardiac sounds, a screening test based on auscultation would seem logical. Though there is a small group of patients in whom auscultation alone is insufficient to make a definite statement regarding the significance of a murmur, the subjective interpretation of auscultatory findings by a trained listener in the majority of cases is more reliable than phonocardiographic recordings. The functional or innocent systolic murmur cannot usually be distinguished from the organic one by graphic methods; also, a faint systolic murmur can be recorded by the phonocardiogram in all children at rest. The great advantage of auscultation, according to Rushmer, is that it apparently involves "those characteristics of auditory perception that allow a person to recognize a familiar voice even when distorted by the telephone."
With the apparatus described, a technician can produce good quality recordings of apical and basilar cardiac sounds from 250 children during an average school day. The physician-listener, after a training period to become proficient with the playback procedure, can evaluate 140 patients per hour. The aim is to pick out those patients who should be recalled for physical examination because of unusual records of "auscultatory" findings.
From the field studies it was apparent that the accuracy of the screening physician was the same whether he employed tape-recordings or clinical auscultation. Furthermore, there was relatively low recall rate of "false positive" interpretations, i.e., 30 per 1,000.
The economy and convenience, as regards the physician's time, for screening large populations for heart disease are apparent. Further investigation by other teams of the ease and accuracy of tape-recording cardiac sounds for case-finding seem indicated.