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

The significance of left ventricular ejection time in heart failure with reduced ejection fraction

Left ventricular ejection time (LVET) is defined as the time interval from aortic valve opening to aortic valve closure, and is the phase of systole during which the left ventricle ejects blood into the aorta. LVET has been used for several decades to assess left ventricular function and contractility. However, there is a recent interest in LVET as a measure of therapeutic action for novel drugs in patients with heart failure with reduced ejection fraction (HFrEF), since LVET is shortened in these patients. This review provides an overview of the available information on LVET including methods of measuring LVET, mechanistic understanding of LVET, association of LVET with outcomes, mechanisms behind shortened LVET in HFrEF and the potential implications of drugs that affect and normalize LVET.

Mechanism of prolongation of pre-ejection period in the hypertrophied left ventricle with normal systolic function in unanesthetized hypertensive dogs

To determine the mechanism for prolongation of pre-ejection period (PEP) in the hypertensive heart with normal systolic function, cardiac catheterizations, echocardiograms, and electrocardiograms were performed at the baseline period (CS, control stage) and eight weeks (HS, hypertensive stage) after the induction of systemic hypertension by Page's method in unanesthetized dogs. Mean aortic blood pressure increased significantly (96 +/- 12 to 137 +/- 26 mmHg) (p less than 0.05). Diastolic aortic pressure also increased significantly (80 +/- 12 to 118 +/- 24 mmHg) (p less than 0.01). Left ventricular (LV) PEP of HS was significantly prolonged (72 +/- 12 vs. 87 +/- 22 ms, CS vs. HS). The ratio of LV pre-ejection period to ejection time (PEP/ET) also increased significantly (0.33 +/- 0.04 to 0.42 +/- 0.07) (p less than 0.05). LV end-diastolic wall stress as an index of preload decreased significantly (7.7 +/- 2.5 vs. 5.9 +/- 1.8 10(3) dynes/cm2, CS vs. HS). Heart rate, mean velocity of circumferential fiber shortening (VCF) and end-systolic wall stress of HS did not change. That is, myocardial contractility in the hypertensive heart of HS most likely is not depressed. At autopsy, left ventricle to body weight ratio of HS was significantly (p less than 0.01) greater than the sham-operated dogs (5.7 +/- 0.8 vs. 4.3 +/- 0.5 g/kg). From these findings, there are two possible factors responsible for prolongation of PEP of HS. First, elevated diastolic aortic pressure may influence PEP. Second, the prolonged PEP is possibly caused by the decrease of preload.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship between systolic time intervals and arterial blood pressure

It has been suggested that systolic time intervals (STI) can be used to monitor the cardiac effects of antihypertensive treatments and also to evaluate hypertensive patients. STI changes observed in hypertensives have been ascribed to myocardial disease, although they could be due to the existence of a relationship between STI and blood pressure. A group of 37 subjects (18 normotensives and 19 hypertensives) with no signs of heart failure and left ventricular dysfunction were studied to examine the relationship of STI to blood pressure. Pacing with an external battery pulse generator was performed at the rate of 95 beats/min in order to eliminate differences in heart rate. STI were measured from good quality high speed (100 mm/s) recordings and the average value of 10 consecutive cardiac cycles was used for statistical analysis. Normal subjects showed significantly lower values of pre-ejection period (PEP), electromechanical systole (QS2), and pre-ejection period/left ventricular ejection time ratio (PEP/LVET). Moreover, a significant inverse relationship between diastolic pressure and LVET and significant direct relationships between diastolic pressure and PEP, systolic pressure and PEP, diastolic pressure and PEP/LVET, and between systolic pressure and PEP/LVET were demonstrated. We suggest to consider the relation of STI to blood pressure to provide regression equations to best appreciate and use STI.