Respiratory sinus arrhythmia: physiological mechanisms and relationship with systemic blood pressure fluctuations

Respiratory sinus arrhythmia (RSA) reflects the functioning of the nervous heart control, predominantly of a parasympathetic nature. The study of RSA mechanisms helps to reveal the physiological patterns of regulation of cardiac activity, and the development of new approaches to its assessment is an urgent medical task. This review will examine experimental approaches that have contributed to the development of modern ideas about autonomic nervous system role in the formation of RSA, as well as the connection between RSA and frequency-matched fluctuations in systemic blood pressure. In addition, we will consider new data on the phase relationships of fluctuations in heart rate and blood pressure in the frequency range of respiratory waves, obtained using wavelet analysis of these physiological signals.