Altered baroreflex gain during voluntary breathing in chronic heart failure

Background: We assessed the behavior of the baroreflex (BR) gain in chronic heart failure (CHF) patients using the spectral analysis method during app lication of a forcing stimulus, i.e. respiration. Methods: Simultaneous RR interval and arterial pressure fluctuation recordings were obtained during two random-order periods of voluntary paced-breathing (0.15 Hz and 0.25 Hz) in seven patients with moderate CHF (NYHA class II/III; EF, 30 +/- 9%; pea k VO2, 18 +/- 5 ml kg(-1) min(-1)) and six age-matched controls. BR gain wa s assessed in the time (sequential method) and frequency (cross-spectral ga in in the low and high frequency) domains. Results: Slower breathing was as sociated with a BR gain decrease in CHF patients whereas a BR gain increase was evidenced in controls (BR gain: 6 +/- 5 ms mmHg(-1) at 0.25 Hz vs. 4 /- 3 ms mmHg(-1) at 0.15 Hz, P < 0.05 in CHF; BR gain: 12 <plus/minus> 7 ms mmHg(-1) at 0.25 Hz vs. 15 +/- 7 ms mmHg(-1) at 0.15 Hz, P < 0.05 in contr ols). Conclusions: Voluntary breathing, which involves cortical centers in the brain, had major effects on cardiovascular system controller gain in CI -IF patients, indicating an impairment of the central neural regulation of the autonomic outflow. (C) 2001 European Society of Cardiology. All rights reserved.