title: Reduced peripheral arterial blood flow with preserved cardiac output during submaximal bicycle exercise in elderly heart failure.
abstract: BACKGROUND
  Older heart failure (HF) patients exhibit exercise intolerance during activities of daily living. We hypothesized that reduced lower extremity blood flow (LBF) due to reduced forward cardiac output would contribute to submaximal exercise intolerance in older HF patients.
  
  
  RESULTS
  Twelve HF patients both with preserved and reduced left ventricular ejection fraction (LVEF) (aged 68 +/- 10 years) without large (aorta) or medium sized (iliac or femoral artery) vessel atherosclerosis, and 13 age and gender matched healthy volunteers underwent a sophisticated battery of assessments including a) peak exercise oxygen consumption (peak VO2), b) physical function, c) cardiovascular magnetic resonance (CMR) submaximal exercise measures of aortic and femoral arterial blood flow, and d) determination of thigh muscle area. Peak VO2 was reduced in HF subjects (14 +/- 3 ml/kg/min) compared to healthy elderly subjects (20 +/- 6 ml/kg/min) (p = 0.01). Four-meter walk speed was 1.35 +/- 0.24 m/sec in healthy elderly verses 0.98 +/- 0.15 m/sec in HF subjects (p < 0.001). After submaximal exercise, the change in superficial femoral LBF was reduced in HF participants (79 +/- 92 ml/min) compared to healthy elderly (222 +/- 108 ml/min; p = 0.002). This occurred even though submaximal stress-induced measures of the flow in the descending aorta (5.0 +/- 1.2 vs. 5.1 +/- 1.3 L/min; p = 0.87), and the stress-resting baseline difference in aortic flow (1.6 +/- 0.8 vs. 1.7 +/- 0.8 L/min; p = 0.75) were similar between the 2 groups. Importantly, the difference in submaximal exercise induced superficial femoral LBF between the 2 groups persisted after accounting for age, gender, body surface area, LVEF, and thigh muscle area (p <or= 0.03).
  
  
  CONCLUSIONS
  During CMR submaximal bike exercise in the elderly with heart failure, mechanisms other than low cardiac output are responsible for reduced lower extremity blood flow.
authors.affiliation: Department of Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA. jirapa2801@yahoo.com
authors.forename: Chirapa
authors.initials: C
authors.lastname: Puntawangkoon
authors.forename: Dalane W
authors.initials: DW
authors.lastname: Kitzman
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Kritchevsky
authors.forename: Craig A
authors.initials: CA
authors.lastname: Hamilton
authors.forename: Barbara
authors.initials: B
authors.lastname: Nicklas
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Leng
authors.forename: Peter H
authors.initials: PH
authors.lastname: Brubaker
authors.forename: W Gregory
authors.initials: WG
authors.lastname: Hundley
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001013:Aorta, Thoracic / Q000503:physiopathology; D001642:Bicycling; D002302:Cardiac Output; D016022:Case-Control Studies; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D005263:Femoral Artery / Q000503:physiopathology; D006333:Heart Failure / Q000188:drug therapy / Q000503:physiopathology*; D006801:Humans; D007083:Iliac Artery / Q000503:physiopathology; D035002:Lower Extremity / Q000098:blood supply*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000098:blood supply / Q000503:physiopathology; D012039:Regional Blood Flow; D013318:Stroke Volume; D016277:Ventricular Function, Left