Autonomic Regulation of Cardiovascular Function in Health and Disease

Abstract

The system that controls the cardiovascular activity is the autonomic nervous system (ANS), which coordinates changes in heart rate, contractile power, and vascular tone moment-to-moment to ensure homeostasis. This hierarchal system uses a balance of sympathetic (fightor-flight) and parasympathetic (rest-and-digest) limbs, which is controlled by brainstem and hypothalamus central command centers. Its mechanism depends on chemical neurotransmission acetylcholine, norepinephrine, as well as fast reflex responses, mostly the baroreflex to maintain hemodynamic equilibrium. This has been shown in health by strong heart rate variability (HRV) and respiratory sinus arrhythmia, which is a measure of autonomic flexibility. Autonomic imbalance on the other hand, which is characterised by sympathetic hyperactivity and parasympathetic withdrawal, is one of the most important pathophysiological processes in heart failure, hypertension, and arrhythmias. The measurement of autonomic activity employs instruments, such as clinical reflexes, to more complex methods of quality such as HRV, baroreflex sensitivity, and microneurography. The therapeutic interventions have developed on the basis of pharmacological principles beta-blockers, RAAS inhibitors to novel device-based neuromodulation which includes vagus nerve stimulation and renal denervation. The future of cardiovascular medicine is in individualized neuromodulation, which builds on the profound knowledge of autonomic physiology to work towards dysregulation with ever greater specificity