Systolic time intervals.

The systolic time intervals (STI) offer temporal description of the sequential phases of cardiac cycle which are influenced physiologically by the same variables as affect other measures of left ventricular (LV) performance. The STI hence offer a measure of ventricular function which augments other measures of ventricular performance. Because of the extreme sensitivity of this variable and the ease of its measurement the STI are well suited for studying the effect of pharmacologic agents upon the heart.