Introduction to heart rate variability

Abstract

Beat-to-beat intervals of cardiac sinus rhythm are not constant but show complex and continuous fluctuations called heart rate variability (HRV). Because HRV disappears with cardiac denervation by complete autonomic blockades or cardiac transplantation, HRV is thought to originate from the brain and to transfer to the heart through the autonomic nervous system. HRV includes a plenty of information not only about autonomic neural cardiac regulations but also about health state and hazard that are captured by the brain. To extract information that meets with particular purposes, various methods have been developed for the analysis of HRV. This chapter explains the basic mechanisms generating HRV and introduces the purposes and corresponding methods for HRV analyses.