High-frequency dominant depression of peripheral vagal control of heart rate in rats with chronic heart failure

Aim To examine whether dynamic characteristics of the peripheral vagal control of heart rate (HR) are altered in chronic heart failure (CHF). Methods The right vagal nerve was electrically stimulated according to a binary white noise signal, and the transfer function from vagal nerve stimulation (VNS) to HR was estimated in the frequency range from 0.01 to 1 Hz in five control rats and five CHF rats under anaesthetized conditions. The rate of VNS was changed among 10, 20 and 40 Hz. Results A multiple linear regression analysis indicated that the increase in the VNS rate augmented the ratio of the high-frequency (HF) gain to the steady-state gain in the control group but not in the CHF group. As a result, the dynamic gain of the transfer function in the frequencies near 1 Hz decreased more in the CHF group than in the control group. Conclusion Changes in the dynamic characteristics of the peripheral vagal control of HR may contribute to the manifestation of decreased HF components of HR variability observed in CHF.