Ruchi Kothari

Background: Hypertension, the silent killer is as an important risk factor for cardiac arrest, stroke, kidney disease and increased mortality rates in adults. Heart Rate Variability (HRV) is a physiological phenomenon of variation in the time interval between heartbeats and is a gold-standard to assess the perpetually changing oscillations of a salubrious heart. Early detection of hypertension by a non-invasive tool as HRV can identify the autonomic regulation in hypertensive individuals at high risk for developing cardiovascular morbidities complications.  Aim: To study the autonomic correlates of cardiovascular health in hypertension in terms of short term HRV and to analyze the association between HRV indices and elevated blood pressure. Methods: It was a cross-sectional observational study carried out in Sports Physiology Laboratory in Department of Physiology of a rural medical college in central India. 25 known cases of hypertension (having Systolic BP >140 mmHg and diastolic BP >90 mmHg) in the age group of 35-60 yrs and 75 age matched normotensives as controls (Systolic BP Results: The mean age of control males was 39.80±6.68 and mean age of control females was 37.05±2.75. Out of hypertensives, 17 were males (mean age 42.58 ± 6.94) and 8 were females (mean age 42.6±8.84). There was statistically significant difference observed in SDNN, RMSSD, HF%, HF nu between control and cases males but no significant relationship was observed among other parameters in males. On comparing the sympatho-vagal ratio (LF/HF), female cases were having high ratio than control females indicating a dominant sympathetic response. From Pearson’s correlation analysis, a positive non-significant relationship was observed between systolic BP and Frequency domain indices in controls while in cases a negative correlation was found which was also statistically non-significant. A strong positive correlation was found between Systolic BP and SDNN (r=0.55) in hypertensives. The time domain parameters were also found to be negatively correlated with mean heart rate in both controls and cases. Conclusions: This pioneering study analyzed the association between heart rate variability indices and high blood pressure.  The analysis of HRV can distinguish parasympathetic from sympathetic influences on the heart and provides important insights into the role of the autonomic nervous system in the pathogenesis of essential hypertension. HRV is reduced in men and women with systemic hypertension. Among normotensive men, lower HRV was associated with greater risk for developing hypertension. These findings clearly exhibit that autonomic dysregulation is present in the early stage of hypertension.

Hypertension is among the most significant global health issues to date and is closely related to the autonomic nervous system, as evidenced by short-term heart rate variability (HRV). Short-term HRV is a noninvasive marker of the autonomic regulation of cardiac activity, related to the balance between sympathetic and parasympathetic activity. This is a narrative review on the complex interaction between hypertension and short-term HRV, considering pathophysiological mechanisms, clinical implications, and potential applications in diagnosis and management. Evidence has shown that hypertension is associated with reduced HRV, which means autonomic dysfunction and increased cardiovascular risk. The mechanistic pathways include alterations in increased sympathetic activity, and reduced vagal tone. Decreased HRV has also emerged as a predictor of the development and progression of hypertension, suggesting that it may be a useful biomarker. However, standardization of HRV measurement and interpretation are some of the challenges that have been identified. This review integrates the current knowledge, highlights gaps in understanding, and proposes directions for future research that may help leverage HRV in the management and risk stratification of hypertension.