Heart rate variability in heart failure

The automatic nervous system has an important role in the development and progression of the heart failure syndrome. Increased sympathetic, reduced parasympathetic, and impaired baroreceptor activity are well-documented features of heart failure. The analysis of heart rate variability can given insight into these autonomic abnormalities. A number of techniques now exist for assessing heart rate variability, and in general they reflect the known autonomic abnormalities. Power spectral analysis of RR variability has been claimed to reflect symphatovagal balance, but the reduced or absent low- frequency component in heart failure is paradoxical. It is likely that the absent low-frequency component in heart failure reflects impaired baroreceptor function. Although these various techniques of heart rate variability may be useful, reliability and reproducibility are problematic in this area. Better, more refined techniques for the noninvasive assessment of autonomic and baroreceptor function are still needed.