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 QS_t 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 QS_1’ 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.

No abstract

Comparison of the antegrade and retrograde (collateal) coronary free flows showed that the retrograde flow was less than 10 per cent of the antegrade flow in 48 per cent of animals and above 20 per cent in 11 per cent of animals.