Chronic heart failure. The relationship between increased activity of skeletal muscle ergoreceptors and reduced exercise tolerance.

BACKGROUND

In chronic heart failure (CHF), skeletal muscle abnormalities may lead to the overactivation of ergoreceptors which in turn may cause sympathetic overactivation and increased ventilatory response to exercise.

AIM: To assess ergoreceptor reflex response to exercise and to evaluate whether ergoreceptor overactivity is related to the progression of CHF.

METHODS

In 69 patients with CHF (66 males, mean age 62.7+/-11.6 years, NYHA class I/II/III/IV - 11/32/24/2 patients, respectively) and 24 controls without CHF (22 males, mean age 59+/-4.6 years) the ergoreflex contribution to the ventilatory and haemodynamic responses to exercise was evaluated. Moreover, in 13 patients with CHF, reproducibility of the measurements was assessed by repeating the test 1 to 7 days later.

RESULTS

Enhanced ergoreflex effects on ventilation (1.9+/-1.6 vs 0.14+/-0.7 l/min, p<0.05) and systolic blood pressure (19.2+/-14.9 vs 6.1+/-5.9 mmHg, p<0.05) were found in patients with CHF compared with control subjects. Ergoreceptor overactivity was associated with a worse symptomatic state (NYHA class I vs II vs III, IV: 0.9 vs 1.5 vs 2.9 l/min, p<0.05) and lower exercise tolerance (peak V0(2): r=-0.51, p<0.0001; VE/VC0(2): r=0.50, p<0.0001). The mean values of the ergoreceptor reflex did not differ significantly between the two tests (t=1.5, p=0.14; variability coefficient = 21.5%).

CONCLUSIONS

In CHF, overactivation of the ergoreflex is associated with the progression of the syndrome and may be responsible for reduced exercise tolerance. Reproducibility of ergoreflex measurements is satisfactory.