Mechanisms of respiratory sinus arrhythmia in patients with mild heart failure

Magdi El-Omar, Attila Kardos, Barbara Casadei
2001 American Journal of Physiology. Heart and Circulatory Physiology  
dei. Mechanisms of respiratory sinus arrhythmia in patients with mild heart failure. Am J Physiol Heart Circ Physiol 280: H125-H131, 2001.-The high-frequency (HF) component of the heart rate variability (HRV) is regarded as an index of cardiac vagal responsiveness. However, when vagal tone is decreased, nonneural mechanisms could account for a significant proportion of the HF component. To test this hypothesis, we examined the HRV spectral power in 20 patients with mild chronic heart failure
more » ... ic heart failure (CHF) and 11 controls before and during ganglion blockade with trimethaphan camsylate (3-6 mg/min iv). A small HF component was still present during ganglion blockade, and its amplitude did not differ between CHF patients and controls. The average contribution of nonneural oscillations to the HF component was 15% (range 1-77%) in patients with CHF and 3% (range 0.7-30%) in healthy controls (P Ͻ 0.005). During controlled breathing at 0.16 Hz, however, it decreased to 1% (range 0.2-13%) in healthy controls and 5% (range 1-44%) in CHF patients. Our results indicate that the HF component can significantly overestimate cardiac vagal responsiveness in patients with mild CHF. This bias is improved by controlled breathing, since this maneuver increases the vagal contribution to HF without affecting its nonneural component. autonomic nervous system; vagus nerve; stretch Address for reprint requests and other correspondence: B. Casadei, University
doi:10.1152/ajpheart.2001.280.1.h125 pmid:11123226 fatcat:4higkddi7rfvld4ghdocxqzmee