Heart rate variability in hypertensive patients with left ventricular diastolic dysfunction

ABSTRACT

This study aimed to evaluate the role of autonomic nervous system in determining the appearance of diastolic ventricular dysfunction in patients with previously unrecognized and untreated essential hypertension. Sixty middle aged and pharmacologically untreated hypertensive subjects [45 men and 15 women] and 30 normotensive subjects [24 men and 6 women] as a control group [group I] were studied. All patients were referred from outpatient clinic with blood pressure morethan 140/90 mmHg as detected by ambulatory blood pressure monitoring with an auscultatory device. Echocardiography was done to assess left ventricular diastolic function. Exercise ECG test was done to exclude patients with ischaemic 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 30 patients with diastolic dysfunction and group III included 30 patients with normal ventricular systolic function. In regard of age, gender, left ventricular mass index and left ventricular systolic function, there was no significant difference between all the groups of study; but the hypertensive patients of group II had a significant decreased E/A ratio, a significant decreased r-MSSD and p-NN50 and a significant increased daytime and nighttime heart rate than subjects and patients of groups I and II. There was a significant correlation between vagal dependent parameter [r-MSSD] and E/A ratio. Stepwise logistic analysis revealed that there was no significant relation between age, gender and ambulatory systolic and diastolic blood pressure and the presence of left ventricular diastolic dysfunction in hypertensive patients. It was concluded that 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 treatments that increase vagal tone