Phonocardiographic Recordings of First and Second Heart Sound in Determining the Systole/Diastole-Ratio during Exercise Test

Abstract

The objective was to examine whether a microphone can be used to detect first and second heart sound during an exercise test and if these recordings can be used to calculate S/D-ratios in healthy subjects. Furthermore the objective was to describe the changes in systolic and diastolic duration under cardiac stress.

Nine healthy subjects (5M, 4F) completed a standardized exercise test while wearing a Panasonic microphone incorporated in a specially designed coupler. Recordings of heart sounds were made with Acarix Data Acquisition System at the end of each workload level.

As heart rate increased, the recordings became more difficult to interpret as did detection of first and second heart sounds. Recordings from female subjects were easier to interpret than those of male subjects. As heart rate increased, the S/D-ratio increased accordingly. The development of systole and diastole duration was very similar in male and female subjects.

First and second heart sound can be detected using a microphone, but noise at higher load levels necessitates the development of a noise-reducing filter. Furthermore the duration of systole and diastole was found altered during stress. The systole duration decreased minimally whilst the diastole duration decreased markedly as a function of higher heart rate.