A focus on the assessment of the autonomic function using heart rate variability

Heart rate variability (HRV), the variation in the time interval between successive heartbeats, has emerged as a method to evaluate autonomic function and is increasingly accepted as a biomarker reflecting the balance between the sympathetic and parasympathetic nervous system (SNS and PNS, respectively) branches. Since 1996, most HRV measurements have been performed according to the Task Force standards of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology. However, despite the established guidelines and growing body of research on HRV, this technique has not been fully incorporated into routine clinical practice. This review provides a comprehensive overview of the different aspects of HRV measurement, highlighting the fundamental principles, available methods, and physiological basis of HRV assessment to elucidate its role in understanding autonomic function in normal and abnormal health conditions.