Systolic time intervals by echocardiography.

Technical difficulties in recording phonocardiogram or indirect carotid pulse occasionally preclude determination of the systolic time intervals. Accordingly, an alternative method was tested in 52 patients, using high-speed strip chart recording of the aortic valve echocardiogram. Satisfactory records were obtained in 36. The interval from opening to closing of the aortic valve (ejection time) was subtracted from the interval between the Q wave of the electrocardiogram and the closing of the aortic valve (total electromechanical systole) to provide the pre-ejection period. When these intervals and the pre-ejection period/ejection time ratio were compared to corresponding values obtained by conventional methods from the simultaneously recorded phonocardiograms and indirect carotid pulses, a high degree of correlation (r greater than 0.97) was found. Differences between the two methods for each interval were insignificant, being greatest in the case of the ejection time but never exceeding 16 msec. These findings indicate that the echocardiogram of the aortic valve provides an alternative, noninvasive method for determination of the systolic time intervals whenever the usual methods fail.