Objective To better understand the hemodynamic and autonomic reflex abnormalities in heart-failure patients (HF), we investigated the influence of group III/IV muscle afferents on their cardiovascular response to rhythmic exercise. Methods Nine HF-patients (NYHA class-II, mean left ventricular ejection-fraction: 27 ± 3%) performed single leg knee-extensor exercise (25/50/80% peak-workload) under control conditions and with lumbar intrathecal fentanyl impairing μ-opioid receptor-sensitive muscle afferents. Results Cardiac-output (Q) and femoral blood-flow (QL) were determined, and arterial/venous blood samples collected at each workload. Exercise-induced fatigue was estimated via pre/post-exercise changes in quadriceps strength. There were no hemodynamic differences between conditions at rest. During exercise, Q was 8-13% lower with Fentanyl-blockade, secondary to significant reductions in stroke volume and heart rate. Lower norepinephrine spillover during exercise with Fentanyl revealed an attenuated sympathetic outflow that likely contributed to the 25% increase in leg vascular conductance (p < 0.05). Despite a concomitant 4% reduction in blood pressure, QL was 10-14% higher and end-exercise fatigue attenuated by 30% with Fentanyl-blockade (p < 0.05). Conclusion/practice/implications Although group III/IV muscle afferents play a critical role for central hemodynamics in HF-patients, it also appears that these sensory neurons cause excessive sympatho-excitation impairing QL which likely contributes to the exercise intolerance in this population.
|Titolo:||Group III/IV muscle afferents impair limb blood in patients with chronic heart failure|
VENTURELLI, MASSIMO (Secondo)
|Parole Chiave:||Autonomic control; Circulation; Exercise pressor reflex; Sensory neurons|
|Settore Scientifico Disciplinare:||Settore M-EDF/02 - Metodi e Didattiche delle Attivita' Sportive|
|Data di pubblicazione:||2014|
|Digital Object Identifier (DOI):||10.1016/j.ijcard.2014.04.157|
|Appare nelle tipologie:||01 - Articolo su periodico|