VARIABILITY OF HEART-RATE AND CARDIAC-FAI LURE

Under pathological conditions, the autonomic nervous system, which con tinually regulates cardiac function, may have adverse effects on pump function and electrical activation. The sinus rhythm is an indirect ma rker of the different components of the autonomic nervous system and c hanges in the heart rate reflect the permanent variation of vagal and sympathetic tone. Analysis of variability in the temporal or frequenti al domaines, provides information about the modulation of the differen t components of the autonomic nervous system. In the post-infarction p eriod, studies have shown that the heart rate variability is an indepe ndant predictive factor of cardiovascular mortality. The data availabl e in patients with cardiac failure is limited. There is a decrease in heart rate variability and this decrease seems to be associated with a higher risk.