Decreased vagal dependent time-domain heart rate variability in hypertensive patients with left ventricular diastolic dysfunction

ABSTRACT

To evaluate the role of the autonomic nervous system in determining the appearance of diastolic ventricular dysfunction in patients with previously unrecognized and untreated essential hypertension. We studied 100 middle-aged and pharmacologically untreated hypertensive subjects [88 men and 12 women] and 50 normotensive subjects [44 men and 6 women] as a control group [group I]. A l l patients were referred from the outpatient clinic in Farwania Hospital with blood pressure more than 140/90 mmHg as detected by ambulatory blood pressure monitoring with an auscltatory device. Echocardiography was done to assess left ventricular diastolic function. Exercise ECG test was done to exclude patients with ischemic heart disease. Holter ECG monitor was done for all subjects to assess heart rate variability. Hypertensive patients were classified into two groups group II included 50 patients with diastolic dysfunction and group III included 50 patients with normal ventricular diastolic function. With respect to age, gender, left ventricular mass index and left ventricular systolic function there were no significant difference between all groups of study [P = NS]. The hypertensive patients of group II had a significant decreased E/A ratio [P < 0.05], a significant decreased r-MSSD and p-NN50 [P < 0.05] and a significant increased daytime and nighttime heart rate [P < 0.05] than subjects and patients of groups I and III. There was a significant correlation between vagal dependent parameter [r-MSSD] and E/A ratio [r = 0.875, P < 0.05]. Stepwise logistic analysis revealed no significant relation between age, gender and ambulatory systolic and diastolic blood pressure and the presence of left ventricular diastolic dysfunction in hypertensive patients. Left ventricular diastolic dysfunction in hypertensive patients without left ventricle hypertrophy is related to reduced parasympathetic activity and this supports the use of non-pharmacologic treatment that increases diastolic vagal tone