Influence of the metaboreflex on arterial blood pressure in heart failure patients.

Background: Feedback from active locomotor muscles contributes to the exercise pressor response in healthy humans, and is thought to be more prominent in heart failure (HF). The purpose of this study was to examine the influence of metaboreflex stimulation on arterial pressure in HF.
Methods: Eleven HF patients (51 ± 5 years, New York Heart Association Class I/II, left ventricular ejection fraction 32 ± 3%) and 11 controls (42 ± 3 years) were recruited. Participants completed two exercise sessions on separate days: (1) symptom limited graded exercise test; and (2) constant work rate cycling (60% peak oxygen consumption,V˙O2) for 4 minutes with 2 minutes passive recovery. Recovery was randomized to normal or locomotor muscle regional circulatory occlusion (RCO). Mean arterial pressure (MAP), systolic pressure (SBP), diastolic pressure, heart rate (HR) and V˙O2 were measured at rest, end-exercise and recovery. O2 pulse (V˙O2/HR) and the rate pressure product (RPP = HR × SBP) were calculated.
Results: In response to RCO, mean arterial pressure and SBP increased in HF compared with CTLs (6.8 ± 5.8% vs -3.0 ± 7.8%, P < .01 and 3.4 ± 6.4% vs -12.7 ± 10.4%, P < .01, respectively), with no difference in diastolic pressure (P = .61). HF patients had a smaller reduction in HR and RPP, but also displayed a larger decrease in O2 pulse consequent to locomotor metaboreflex stimulation (P < .05, for all).
Conclusion: RCO resulted in a markedly increased pressor response in HF relative to controls, due primarily to an increase of SBP and attenuated cardiac recovery as noted by the persistent elevation in HR.
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