Ives Stephen J, Amann Markus, Venturelli Massimo, Witman Melissa A H, Groot H Jonathan, Wray D Walter, Morgan David E, Stehlik Josef, Richardson Russell S
1Geriatric Research, Education, and Clinical Center, George E. Wahlen Department of Veteran Affairs Medical Center, Salt Lake City, UT; 2Department of Internal Medicine, University of Utah, Salt Lake City, UT; 3Health and Exercise Sciences Department, Skidmore College, Saratoga Springs, NY; 4Department of Exercise and Sport Science, University of Utah, Salt Lake City, UT; 5Department of Biomedical Sciences for Health, University of Milan, Milan, ITALY; 6Department of Kinesiology and Applied Physiology, University of Delaware, Newark, DE; and 7Department of Anesthesiology, University of Utah, Salt Lake City, UT.
Med Sci Sports Exerc. 2016 Mar;48(3):368-76. doi: 10.1249/MSS.0000000000000782.
Sensitization of mechanosensitive afferents, which contribute to the exercise pressor reflex, has been recognized as a characteristic of patients with heart failure (HF); however, the hemodynamic implications of this hypersensitivity are unclear.
The present study used passive leg movement (PLM) and intrathecal injection of fentanyl to blunt the afferent portion of this reflex arc to better understand the role of the mechanoreflex on central and peripheral hemodynamics in HF.
Femoral blood flow (FBF), mean arterial pressure, femoral vascular conductance, HR, stroke volume, cardiac output, ventilation, and muscle oxygenation of the vastus lateralis were assessed in 10 patients with New York Heart Association class II HF at baseline and during 3 min of PLM both with fentanyl and without (control).
Fentanyl had no effect on baseline measures but increased (control vs fentanyl, P < 0.05) the peak PLM-induced change in FBF (493 ± 155 vs 804 ± 198 ΔmL·min(-1)) and femoral vascular conductance (4.7 ± 2 vs 8.5 ± 3 ΔmL·min(-1)·mm Hg)(-1) while norepinephrine spillover (103% ± 19% vs 58% ± 17%Δ) and retrograde FBF (371 ± 115 vs 260 ± 68 ΔmL·min(-1)) tended to be reduced (P < 0.10). In addition, fentanyl administration resulted in greater PLM-induced increases in muscle oxygenation, suggestive of increased microvascular perfusion. Fentanyl had no effect on the ventilation, mean arterial pressure, HR, stroke volume, or cardiac output response to PLM.
Although movement-induced central hemodynamics were unchanged by afferent blockade, peripheral hemodynamic responses were significantly enhanced. Thus, in patients with HF, a heightened mechanoreflex seems to augment peripheral sympathetic vasoconstriction in response to movement, a phenomenon that may contribute to exercise intolerance in this population.
机械敏感传入神经的致敏作用对运动升压反射有影响，这已被认为是心力衰竭（HF）患者的一个特征；然而，这种超敏反应对血流动力学的影响尚不清楚。
本研究采用被动腿部运动（PLM）和鞘内注射芬太尼来阻断该反射弧的传入部分，以更好地了解机械反射在HF患者的中枢和外周血流动力学中的作用。
在基线时以及在有芬太尼和无芬太尼（对照）的情况下进行3分钟PLM期间，对10例纽约心脏协会II级HF患者的股血流量（FBF）、平均动脉压、股血管传导率、心率、每搏输出量、心输出量、通气和股外侧肌的肌肉氧合进行评估。
芬太尼对基线测量值无影响，但增加了（对照与芬太尼相比，P<0.05）PLM诱导的FBF峰值变化（493±155对804±198ΔmL·min⁻¹）和股血管传导率（4.7±2对8.5±3ΔmL·min⁻¹·mmHg⁻¹），而去甲肾上腺素溢出（103%±19%对58%±17%Δ）和逆行FBF（371±115对260±68ΔmL·min⁻¹）趋于降低（P<0.10）。此外，给予芬太尼导致PLM诱导的肌肉氧合增加更大，提示微血管灌注增加。芬太尼对PLM引起的通气、平均动脉压、心率、每搏输出量或心输出量反应无影响。
虽然传入神经阻滞未改变运动诱导的中枢血流动力学，但外周血流动力学反应显著增强。因此，在HF患者中，增强的机械反射似乎会增强运动时外周交感神经血管收缩，这一现象可能导致该人群运动不耐受。
