EXAMINATION OF VARIABILITY IN ARTERIAL BLOOD-PRESSURE AT REST USING SPECTRAL-ANALYSIS IN HYPERTENSIVE PATIENTS

Introduction: We hypothesize that in essential hypertension sympatheti c nervous activity is related to the development of left ventricular h ypertrophy, which can be regarded as a measure of the severity of hype rtension. Methods: Using spectral analysis, we studied the short-term variability in resting blood pressure and heart rate in essential hype rtensive subjects. We measured blood over 10 min using a Finapres in 8 8 subjects after 20 min rest. We performed echocardiography to evaluat e left ventricular hypertrophy and thereby identified three groups: 23 control subjects (group I), 29 hypertensive subjects (World Health Or ganization criteria) without left ventricular hypertrophy (group II) a nd 36 hypertensive subjects with left ventricular hypertrophy (group I II). None had been treated for hypertension before the study. Results: The variability in blood pressure over a low-frequency period conside red to be a marker of sympathetic activity was significantly increased in group II compared with groups I and III (analysis of covariance ta king into account blood pressure and age). The variability in heart ra te was similar in groups II and III, but both groups had a significant ly reduced variability in heart rate compared with group I. Conclusion : These data, which examine globally using a non-invasive method, all neurohormonal factors associated with the development of left ventricu lar hypertrophy, demonstrate that, in the time course of hypertension, low-frequency oscillations in blood pressure and heart rate are shift ed to a lower level, presumably reflecting altered function of the sym pathetic nervous system. We suggest that spectral analysis of blood pr essure at rest in hypertensive patients can lead to complementary info rmation to single measures of blood pressure and detect differences in the cardiovascular regulatory system.