Abstract
An automatic cardiac sound analyzer newly developed by authors applying an analog data processing system described.
Outline of the analyzer :
1. In order to identify the first and second heart sounds, and systole and diastole of a cardiac cycle, the carotid arterial pulse was adopted for the reference tracing. The sharp rise in rapid ejection phase and the incisura of the carotid arterial pulse were detected from the second derivative of the pulse tracing, and the detected signals were used for reference of the heart sounds. The time lag between the heart sounds and the reference signals was synchronized by a magnetic delay apparatus.
2. Envelope method was used for pattern analysis of heart sounds and murmurs.
3. Results of the analysis was displayed on an illuminated plastic panel in real time. This analyzer gives answers on the following items ; amplitude of heart sounds, innocent and organic systolic murmurs, respiratory and constant splitting of the second heart sound, physiologic third heart sound and gallop, high and low pitched diastolic murmurs and cardiac rhythm disorders.
Screening of abnormal cadiac sounds
In order to test the function of this analyzer, 159 freshmen of uiversity of Tokyo were selected. The analyzer made quite satisfactory diagnosis with 7 false positive and 1 false negative results. This is compatible with the capacity of non-specialist physician.
This false negative case was reexamined after readjustment of the analyzer, and the correct diagnosis was obtained.
