Effect of 60 degrees head-up tilt on systolic time intervals in hypertensive patients.

Time course of systolic time interval (STI) variations during 60 degrees head-up tilt (HUT) was studied in 21 patients with essential hypertension and equal number of age-matched control subjects. ECG, Phonocardiogram and carotid pulse were recorded simultaneously on polygraph. Electromechanical systole (QS2), left ventricular ejection time (LVET), pre ejection period (PEP), PEP/LVET ratio and ejection fraction (EF) were determined immediately after and at 1, 2, 3, 4 and 5 min after the tilt. In hypertensive patients, basal values of PEP and PEP/LVET ratio were insignificantly higher whereas LVET and EF were insignificantly lower as compared to the control subjects. 60 degrees HUT produced significant decrease in LVET (P < 0.001) and EF (P < 0.001) and a significant increase in PEP/LVET ratio (P < 0.001) in control subjects. The changes in hypertensive subjects were similar in pattern but statistically insignificant. It is concluded that tilt-induced changes in STIs are blunted in hypertensive patients.