Incremental large and small muscle mass exercise in patients with heart failure : evidence of preserved peripheral haemodynamics and metabolism

Aim: Doubt still remains as to whether peripheral vascular and skeletal muscle dysfunction accompanies the compromised cardiac function associated with heart failure with reduced ejection fraction (HFrEF). The aim of this study was to examine the effect of HFrEF on the haemodynamic and metabolic responses to exercise with both a large (cycle) and a small [knee extensor (KE)] muscle mass in comparison with well-matched healthy controls (Ctrls). Methods: Utilizing blood sampling and thermodilution blood flow measurements, we studied incremental cycle and KE exercise in 12 patients with HFrEF (ejection fraction: 25 \ub1 3%) and eight Ctrls. Results: Incremental cycle exercise in both groups [heart failure with reduced ejection fraction (HFrEF): 23 \ub1 1 to 116 \ub1 10; Ctrls: 22 \ub1 1 to 137 \ub1 5 W] resulted in a similar rise in blood flow (HFrEF: 1525 \ub1 132 to 4216 \ub1 408; Ctrls: 1774 \ub1 161 to 4713 \ub1 448 mL min-1), oxygen uptake (HFrEF: 206 \ub1 24 to 586 \ub1 34; Ctrls: 252 \ub1 21 to 747 \ub1 89 mL min-1) and lactate efflux across the leg (HFrEF: 479 \ub1 122 to 4929 \ub1 1255; Ctrls: 537 \ub1 155 to 5776 \ub1 1010 mm min-1). Vascular resistance fell similarly in both groups with increasing exercise intensity (HFrEF: 66 \ub1 10 to 24 \ub1 3; Ctrls: 69 \ub1 12 to 24 \ub1 4 mmHg L-1 min-1). Incremental KE exercise also revealed similar haemodynamic and metabolic responses in both Ctrls and patients. Conclusion: Although assessed in a relatively small cohort, these data reveal that, when compared with well-matched healthy Ctrls, alterations in peripheral haemodynamics and skeletal muscle metabolism during exercise may not be an obligatory accompaniment to HFrEF