Physiological Basis and Clinical Significance of Heart Rate Variability

Abstract

Heart rate variability (HRV) serves as a critical non-invasive biomarker of autonomic nervous system (ANS) activity, highlighting the continuous interaction between sympathetic and parasympathetic pathways in modulating cardiovascular activity. This review elucidates the physiological foundations of HRV, including mechanisms such as respiratory sinus arrhythmia, baroreflex oscillations, and thermoregulatory adjustments. Clinically, HRV demonstrates significant utility in predicting cardiovascular risks, diabetic neuropathy progression, psychological stress, and systemic inflammation. Measurement techniques, such as time-domain and frequency-domain analyses, are discussed alongside their methodological challenges, including respiratory artifacts, protocol inconsistencies, and confounding factors like medications. While HRV’s prognostic value in conditions like myocardial infarction and heart failure is well-established, debates persist over the interpretation of spectral components, such as the controversial LF/HF ratio. Standardization of protocols and mechanistic clarity are urgently needed to enhance HRV’s reliability. By bridging physiological insights with clinical applications, this review underscores HRV’s potential as a versatile tool in personalized medicine, while advocating for interdisciplinary research to address existing limitations.