Serial measurements of systolic time intervals: effects of propranolol alone and combined with other agents in hypertensive patients.
Systolic time intervals (STI) were recorded serially before and during 1 year of treatment in 367 hypertensive men. The patients were randomly assigned, double-blind, to one of the following regimens: propranolol alone (P), propranolol plus hydrochlorothiazide (P + T), propranolol plus hydralazine (P + H), propranolol plus hydrochlorothiazide plus hydralazine (P + T + H), or reserpine plus hydrochlorothiazide (R + T). Systolic time intervals were calculated by a computer pattern-recognition and measurement program. Diastolic blood pressure and heart rate (HR) decreased with each treatment regimen. The preejection period (PEP) was prolonged following P alone. The left ventricular ejection time (LVET), after correction for HR, was shortened with P + T and R + T and prolonged after P + H. The PEP/LVET was reduced with P + H. The prolongation of PEP during long-term administration of P is comparable with previous studies of its acute effects and suggests a moderate decrease in left ventricular performance. Calculation of STI also appears to be a useful method for showing the effects of adding other antihypertensive agents.