title: Skeletal muscle microcirculatory abnormalities are associated with exercise intolerance, ventilatory inefficiency, and impaired autonomic control in heart failure.
abstract: BACKGROUND
  Several skeletal muscle abnormalities have been identified in patients with chronic heart failure (CHF), including endothelial dysfunction. We hypothesized that skeletal muscle microcirculation, assessed by near-infrared spectroscopy (NIRS), is impaired in CHF patients and is associated with disease severity.
  
  
  METHODS
  Eighty-three stable patients with mild-moderate CHF (72 males, mean age 54 ± 14 years, body mass index 26.7 ± 3.4 kg/m(2)) and 8 healthy subjects, matched for age, gender and body mass index, underwent NIRS with the vascular occlusion technique and cardiopulmonary exercise testing (CPET) evaluation on the same day. Tissue oxygen saturation (StO(2), %), defined as the percentage of hemoglobin saturation in the microvasculature compartments, was measured in the thenar muscle by NIRS before, during and after 3-minute occlusion of the brachial artery. Measurements included StO(2), oxygen consumption rate (OCR, %/min) and reperfusion rate (RR, %/min). All subjects underwent a symptom-limited CPET on a cycle ergometer. Measurements included VO(2) at peak exercise (VO(2)peak, ml/kg/min) and anaerobic threshold (VO(2)AT, ml/kg/min), VE/VCO(2) slope, chronotropic reserve (CR, %) and heart rate recovery (HRR(1), bpm).
  
  
  RESULTS
  CHF patients had significantly lower StO(2) (75 ± 8.2 vs 80.3 ± 6, p < 0.05), lower OCR (32.3 ± 10.4 vs 37.7 ± 5.5, p < 0.05) and lower RR (10 ± 2.8 vs 15.7 ± 6.3, p < 0.05) compared with healthy controls. CHF patients with RR ≥9.5 had a significantly greater VO(2)peak (p < 0.001), VO(2)AT (p < 0.01), CR (p = 0.01) and HRR(1) (p = 0.01), and lower VE/VCO(2) slope (p = 0.001), compared to those with RR <9.5. In a multivariate analysis, RR was identified as an independent predictor of VO(2)peak, VE/VCO(2) slope and HRR(1).
  
  
  CONCLUSIONS
  Peripheral muscle microcirculation, as assessed by NIRS, is significantly impaired in CHF patients and is associated with disease severity.
authors: First Critical Care Medicine Department, Cardiopulmonary Exercise Testing and Rehabilitation Laboratory, Evgenidio Hospital, NKUA, Athens, Greece.
authors: Christos
authors: C
authors: Manetos
authors: Stavros
authors: S
authors: Dimopoulos
authors: Georgios
authors: G
authors: Tzanis
authors: Stella
authors: S
authors: Vakrou
authors: Athanasios
authors: A
authors: Tasoulis
authors: Chris
authors: C
authors: Kapelios
authors: Varvara
authors: V
authors: Agapitou
authors: Argirios
authors: A
authors: Ntalianis
authors: John
authors: J
authors: Terrovitis
authors: Serafim
authors: S
authors: Nanas
mesh_terms: D000328:Adult; D000368:Aged; D017776:Autonomic Pathways / Q000503:physiopathology*; D016022:Case-Control Studies; D002908:Chronic Disease; D003430:Cross-Sectional Studies; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D006333:Heart Failure / Q000150:complications / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008833:Microcirculation / Q000502:physiology*; D055806:Microvessels / Q000503:physiopathology*; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000098:blood supply*; D010101:Oxygen Consumption / Q000502:physiology; D011379:Prognosis; D012131:Respiratory Insufficiency / Q000209:etiology / Q000503:physiopathology*; D012720:Severity of Illness Index; D019265:Spectroscopy, Near-Infrared