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.

Serial measurements of systolic time intervals during treatment with hydrochlorothiazide alone and combined with other antihypertensive agents.

As part of the Veterans Administration cooperative studies on antihypertensive agents, systolic time intervals (STIs) were recorded before and after 2 or 4 weeks of treatment with hydrochlorothiazide (HCTZ) alone in 320 asymptomatic patients with mild to moderate hypertension. After treatment with HCTZ, left ventricular ejection time corrected for heart rate (delta LVET) was significantly reduced. This decrease is consistent with other hemodynamic observations indicating a reduced preload and stroke volume after administration of thiazides. Electromechanical systole corrected for heart rate (delta QS2) decreased, while the ratio of preejection period to LVET (PEP/LVET) increased, reflecting reduced left ventricular function. PEP did not change. Four step 2 drugs--hydralazine, prazosin, oxprenolol and propranolol--were then added randomly to HCTZ and further recordings of STIs were taken at 1 and 6 months after administration of these drugs. The delta LVET and delta QS2 increased and PEP/LVET decreased, suggesting improved left ventricular function after administration of all 4 agents. These changes may have been due to the added agents or to the recovery of cardiac output that occurs independently during long-term treatment with thiazide diuretic drugs alone. PEP decreased slightly after hydralazine and prazosin and increased slightly after treatment with the beta-blocking drugs, although none of these changes were significant except those during hydralazine treatment. Processing of the STIs was greatly facilitated by the automated system for recording and analyzing the measurements.

First derivative of the apex cardiogram and systolic time intervals in evaluation of myocardial contractility in man.

The sensitivity of various systolic ... myocardial contractility.

A new microcomputer-based ECG analysis system.

A new automated ECG system using advances in microprocessor technology and computerized electrocardiography is described. This microcomputer-based system is self-contained and mobile. It acquires both the 12-lead and orthogonal lead (Frank) electrocardiograms and analyzes the latter within minutes. Software includes the program developed in the Veterans Administration which uses advanced statistical classification techniques and a large well-documented patient data base. Diagnostic probabilities are computed using a Bayesian approach. Diagnostic performance has been tested using independent clinical criteria and found to be quite accurate. This system enables the clinician to immediately review the computer's identifications, measurements, and diagnostic classifications and quickly use these results in clinical decision making. Serial comparisons are readily made since all previous recordings are stored on floppy diskettes. The use of microprocessors in this system makes it economically feasible for practicing physicians.

Clinical study of ticrynafen. A new diuretic, antihypertensive, and uricosuric agent.

In a double-blind study, 20 hypertensive patients were randomly assigned to a six-week regimen of either ticrynafen or hydrochlorothiazide. Blood pressure was significantly reduced with both medications, although most patients required an increase in dosage from 250 to 500 mg ticrynafen daily. Whereas the serum uric acid level rose moderately in the hydrochlorothiazide-treated patients, it fell strikingly to less than half of the pretreatment level in patients treated with ticryafen. Body weight decreased slightly in both groups, as did serum potassium levels. Blood urea nitrogen and serum creatinine levels rose slightly in both groups. The magnitude of these changes was not significantly different between the two groups. Use of ticryafen was well tolerated. Ticryafen appears to be a useful new antihypertensive agent because of its unique combination of diuretic, antihypertensive, and hypouricemic effects.