Blunted arterial baroreflex causes "pathological" heart rate turbulence.

Abstract

Sudden cardiac death is the leading cause of cardiovascular mortality in developed countries. Recently, two post-myocardial-infarction risk predictors were introduced that are superior to all other presently available indicators: turbulence onset (TO) and turbulence slope (TS). These parameters characterize the behavior of instantaneous heart rate after a ventricular premature beat, i.e., they describe the reestablishing of heart rate control after an acute perturbation. We propose that the dysfunction of an important cardiovascular control mechanism, the arterial baroreflex, is the mechanism behind these new potent markers. The hypothesis is tested by means of a physiological model involving the excitation generation in the heart, the hemodynamic situation in the aorta, and baroreceptor feedback mechanisms. The data show that a blunted baroreceptor response of the heart resembles patterns of heart rate turbulence that correspond to pathological values of TO and TS. The results of the model suggest that the recently established risk parameters TO and TS characterize baroreflex function, a known risk stratifier in patients.