Background: The main symptoms of chronic heart failure are breathlessness and fatigue on exertion. Abnormalities of skeletal muscle cause early metabolic distress on exercise, with resultant ergoreceptor stimulation causing increased ventilation. The aim of this study is to determine the extent of enhanced ergoreflex activity in chronic heart failure in the leg.
Methods: Ten patients with chronic stable heart failure (New York Heart Association class II-III) and nine healthy age-matched controls performed two bouts of ankle dorsiflexion. On one occasion a cuff was inflated round the thigh to suprasystolic levels for 3 min immediately post-exercise: regional circulatory occlusion. Recovery with regional circulatory occlusion was compared to recovery without it.
Results: Systolic and diastolic blood pressure and ventilation were higher after 3 min post-exercise regional circulatory occlusion than after 3 min control recovery in the patient group (184+/-13.3 vs. 165+/-12.5 mm Hg, P<0.01, 94+/-4.7 vs. 86+/-3.5 mm Hg, P<0.05, 9.8+/-0.7 vs. 7.9+/-0.36 l/min, P<0.01). Systolic and diastolic blood pressure were higher after post-exercise regional circulatory occlusion than after control recovery in the control group (149+/-7.8 vs. 138+/-5.7 mm Hg, P<0.01, 86+/-3.3 vs. 82+/-2.5 mm Hg, P<0.05), but this was not the case for ventilation (8.1+/-0.62 vs. 8.1+/-0.62 l/min). Ergoreflex activity was greater in the patient group than in the controls for systolic blood pressure (91 vs. 48%, P<0.001), diastolic blood pressure (86 vs. 49%, P<0.05) and ventilation (39 vs. -1%, P<0.05).
Conclusions: Ergoreceptor stimulation contributes to an increased ventilation and blood pressure response to leg exercise in chronic heart failure patients, perhaps contributing to dyspnoea and exercise limitation. Peripheral factors such as skeletal muscle abnormalities contribute to the pathogenesis of symptoms in chronic heart failure.