Minimization of Heart Rate Bias in the Estimation of Heart Rate Variability

Background: Heart Rate (HR) is a time varying signal indicating the beating activity of the heart, whereas Heart Rate Variability (HRV) is a noninvasive tool to evaluate the cardiac autonomic regulations. The HRV is widely used to evaluate cardiac/autonomic health in normal healthy as well as chronic diseased population. The HR and HRV are significantly connected with each other. HRV is dependent on the average HR as well on the Autonomic Nervous System (ANS) activity. To make the HRV a potential marker of ANS activity, the influence of HR must be reduced. The present study is designed to minimize the effect of HR on HRV by normalization of the RR interval tachogram. Method: Forty six young adults participated in the non-invasive and benign study. 10 minutes of Electrocardiogram (ECG) lead II was recorded in each case in supine position. The electrocardiographic records of the subjects were divided into three groups based on their HR viz., slow, moderate and fast HR. The HRV indices were extracted at pre and post HR bias minimization. Results: The improved HRV was observed with HR bias minimization in all three categories of HR. The reduced HRV was found with increasing heart rate even after HR bias minimization. Conclusion: Significant impact of normalization was found on moderate and fast HR subjects. This suggests that the HRV studies would yield better results with HR bias reduced, thereby improving health monitoring systems based on HRV.