Relationship between systolic time intervals and arterial blood pressure

Abstract

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.

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“…This approximation was used in the derivation of Equation (6b) from Equation (6a), with P ART replacing X. The data series for peak arterial blood pressure P ART found in De Scalzi et al 18 provided support for this approximation. For normotensives, Var(X) / [E(X)] 2 = 12.4 2 / 128.6 2 = 0.0093, and for hypertensives it is 22.4 2 / 175.7 2 = 0.0163…”

“…The mathematical relationship between measured P ART and measured B ART can then be readily determined by curve fitting, which then allows calculation of B ART from any cuff-measured P ART .The duration of arterial systole B ART is known to increase with arterial blood pressure. In 1986, De Scalzi et al18 reported that normal subjects have significantly lower values of average B ART compared to hypertensives [341.7 ± 18.4 ms versus 355.1 ± 15.2 ms (p < 0.025)]. Hence, average B ART in hypertensives is approximately 4% longer than the B ART average in normotensives (355.1 ms /341.7 ms).…”