[Heart rate turbulence--a new ECG predictor for risk of sudden death].

Heart Rate Turbulence (HRT) is a newly described physiological chronotropic response of sinus rhythm following a single ventricular premature beat (VPB) consisting of early acceleration and later deceleration of heart rate. Using two large independent cohorts of postinfarction patients, the absence of HRT was retrospectively validated to be a potent multivariate risk predictor, stronger than a number of currently available risk stratifiers. Although exact pathophysiological mechanism of HRT remains speculative, it is now believed that HRT arises from the haemodynamic changes and baroreceptor reflexes that occur following a VPB. Therefore, HRT descriptors (Turbulence Onset and Turbulence Slope) may serve as very reasonable, Holter--based surrogates of baroreflex sensitivity available in clinical practice. The aim of this review is to summarise the current knowledge on pathophysiological mechanisms of HRT and to discuss practical problem of its detection.