CONTRIBUTION OF MUSCLE AFFERENTS TO THE HEMODYNAMIC, AUTONOMIC, AND VENTILATORY RESPONSES TO EXERCISE IN PATIENTS WITH CHRONIC HEART-FAILURE - EFFECTS OF PHYSICAL-TRAINING

Background A neural linkage between peripheral abnor malities and the exaggerated exercise responses in chronic heart failure (CHF) was post ulated. We studied the ergoreceptors (afferents sensitive to skeletal muscle work) in CHF and whether training can affect their activity. Me thods and Results In 12 stable CHF patients (ejection fraction [EF] = 26.4%) and 10 control subjects (EF=55.3%), we compared the responses t o dynamic handgrip and during a S-minute period of posthandgrip region al circulatory occlusion (PH-RCO). The ergoreflex contribution was qua ntified as the percentage responses to exercise maintained by PH-RCO c ompared with recovery without PH-RCO. Patients showed ergoreflex overa ctivation compared with control subjects in terms of ventilation (86.5 % versus 54.5%), diastolic pressure (97.8% versus 53.5%), and leg vasc ular resistance (108.1% versus 48.9%) (all P<.05). The contribution of the ergoreflex to vagal withdrawal (high frequency of RR variability) and sympathetic activation (low frequency of RR, pressure variability ) was evident in both groups. Nine control subjects and nine CHF patie nts participated in 6 weeks of forearm training. Training reduced the ergoreflex contributions more in CHF than in control subjects: diastol ic pressure (-33.2% versus -4.6%), ventilation (-57.6% versus -24.6%). and leg vascular resistance (-59.9% versus -8.0%) (all P<.05;). Concl usions (1) The ergoreflex role has a larger effect on the responses to exercise in CHF than in control subjects. (2) Training may reduce thi s exaggerated ergoreflex activity, thereby improving the responses to exercise.