Respiratory Sinus Arrhythmia

Abstract

It has been long recognized that the period of the heart, that is, the interval between two heartbeats, changes in rhythm with respiration. Change in heart periods that is synchronous with respiration is called respiratory sinus arrhythmia (RSA). In a healthy person, the heart speeds up during inspiration and slows down during expiration. RSA is perhaps one of the more widely investigated phenomenon in the field of integrative physiology. The objective in this chapter is to introduce the reader to RSA, and it is organized to address the following issues: What is RSA? What are the prominent empirical features of RSA? What are the issues related to measurement of RSA? And, what causes RSA? There is considerable evidence that suggests that RSA is a result of autonomic neural activity. Quantified RSA is simple to measure, yet a powerful index that provides an insight about autonomic nervous activity that governs cardiac function. Given the widely hypothesized dominant role of neural function in cardiac health, this index, identified many centuries ago, continues to be the focus of modern scientific exploration.

Low latency breathing frequency detection and monitoring on a personal computer

“…In general, breathing affects autonomous nervous system so that during inhalation there is an increase in sympathetic activity while during exhalation, there is an increase in parasympathetic activity. As a result, the heart rate increases during inhalation and decreases during exhalation, a phenomena observed as heart rate variability [8][9][10] and commonly explained as respiratory sinus arrhythmia [11][12][13]. In humans and most other vertebrates, breathing is mainly involuntarily driven as it is being controlled by the neurons located in Pre-Bötzinger Complex in the ventrolateral medulla of the brainstem [14][15][16].…”