Clinical significance of systolic time intervals in hypertensive patients

This paper updates the current view on clinical significance of systolic time intervals (STI) in estimating the cardiac changes associated with hypertension. The following three intervals were measured as STI: (1) electromechanical systole (QS2 interval); (2) left ventricular ejection time (LVET) and (3) pre-ejection period (PEP). Firstly, the influences of changes in heart rate, preload, afterload and myocardial contractility upon each interval were reviewed; secondly, clinical applications of STI in various types of hypertension such as essential hypertension, hypertension with angina pectoris and pheochromocytoma were studied. In patients with essential hypertension, there was a good positive correlation between PEP and left ventricular mass, and a shortening of LVET was observed only at the decompensated stage. The changes in STI in angina pectoris with or without hypertension were similar and were different from those in essential hypertensives. STI in patients with pheochromocytoma were characterized by a marked shortening of QS2 and LVET with normal PEP. These findings indicate the usefulness of STI in detecting cardiac changes in various types of hypertension.