Measurements of the electromechanical systole (QS2) and its components: electromechanical delay (QS1), isovolumic contraction time (ICT), and left ventricular ejection time (LVET), were conducted on 30 healthy men at rest and during exercise of varying intensity. The measurements were performed through simultaneous, non-invasive recordings of the electrocardiogram, phonocardiogram, and carotidogram. The conclusions are: (1) QS2 and its components are principally correlated to the duration of the cardiac cycle (RR); (2) in changing posture from supine to sitting, the mean QSt and mean ICT tend to increase, but these changes are not statistically significant. LVET and QS2 are both significantly shortened; (3) during exercise there is a decrease in the mean values of QS1’ ICT, LVET, and QS2. The degree of LVET shortening is not as great as predicted by the ‘resting’ regression equation; (4) variations in arterial blood pressure and work load do not significantly affect systolic time intervals; (5) the effect of age on systolic time intervals is difficult to assess and needs further investigation.

Keywords:
Exercise cardiac dynamics, Exercise and myocardial performance, Cardiac response to exercise, Cardiac cycle time intervals
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© 1974 S. Karger AG, Basel
1974
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