Heart Rate Variability in Patients with Essential Hypertension

Abstract

Background: Essential hypertension may be associated with altered cardiovascular autonomic nerve
function. Heart Rate Variability (HRV) analysis is an important tool for quantitative measurement of
autonomic nerve activity.
Objective: To assess the cardiac autonomic nerve function status in essential
hypertension by analyzing time domain measures of heart rate variability.
Methods: This cross sectional study was carried out in the Department of Physiology, Bangabandhu Sheikh Mujib Medical
University from 1st July 2008 to 30th June 2009.For this purpose, 60 hypertensive male patients with
age ranged between 40-60 years (group B) were enrolled from the Out Patient Department of Cardiology,
BSMMU, Dhaka. Based on treatment received, hypertensive patients were subdivided into group B1
i.e.untreated patients on their 1st day of diagnosis and group B2 i.e.patients with antihypertensive
therapy. For comparison, 30 age & sex matched apparently healthy normotensive subjects (group A)
were also studied as control group. Time domain measures of Heart Rate Variability (HRV) such as
Mean RR intervals, Mean HR, SDNN & RMSSD were assessed by a Polygraph machine to observe
both sympathetic and parasympathetic nerve function status. For statistical analysis of data,
Independent sample t-test, One-way ANOVA test, were used as applicable.
Results: Mean R-R interval SDNN and RMSSD were significantly (P<0.01) lower but mean heart rate was significantly (P<0.01)
higher in untreated hypertensive patients than those of normotensive subjects. But differences in all
these 4 parameters when compared between control and treated hypertensive patients were found
statistically non significant.
Conclusion: Impaired cardiac autonomic nerve function characterized by
sympathetic overactivity may occur in hypertensive patients.

Key words: Mean RR; SDNN; RMSSD; hypertension

DOI: 10.3329/jbsp.v5i1.5411

J Bangladesh Soc Physiol. 2010 June; 5(1): 1-7