Department of Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA.
J Cardiovasc Magn Reson. 2009 Nov 18;11(1):48. doi: 10.1186/1532-429X-11-48.
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.
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).
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.
老年心力衰竭（HF）患者在日常生活活动中表现出运动不耐受。我们假设，由于心输出量减少导致下肢血流量（LBF）减少，这将导致老年 HF 患者亚最大运动不耐受。
12 名 HF 患者（左心室射血分数[LVEF]均保留和降低）（年龄 68 +/- 10 岁），无大（主动脉）或中（髂或股动脉）血管动脉粥样硬化，以及 13 名年龄和性别匹配的健康志愿者接受了一系列复杂的评估，包括 a）峰值运动耗氧量（峰值 VO2），b）身体功能，c）心血管磁共振（CMR）亚最大运动主动脉和股动脉血流测量，以及 d）大腿肌肉面积测定。HF 患者的峰值 VO2 （14 +/- 3 ml/kg/min）较健康老年人（20 +/- 6 ml/kg/min）降低（p = 0.01）。健康老年人的 4 米步行速度为 1.35 +/- 0.24 m/sec，HF 患者为 0.98 +/- 0.15 m/sec（p < 0.001）。亚最大运动后，HF 参与者的股浅动脉 LBF 变化减少（79 +/- 92 ml/min）与健康老年人相比（222 +/- 108 ml/min；p = 0.002）。尽管如此，亚最大压力诱导的降主动脉血流量（5.0 +/- 1.2 vs. 5.1 +/- 1.3 L/min；p = 0.87）和主动脉流量静息基线差（1.6 +/- 0.8 vs. 1.7 +/- 0.8 L/min；p = 0.75）在两组之间相似。重要的是，在考虑年龄、性别、体表面积、LVEF 和大腿肌肉面积后，两组之间亚最大运动诱导的股浅动脉 LBF 差异仍然存在（p < 0.03）。
在老年心力衰竭患者的 CMR 亚最大自行车运动中，除了低心输出量之外，还有其他机制导致下肢血流量减少。
