Hetherington M, Haennel R, Teo K K, Kappagoda T
Am J Cardiol. 1986 Nov 1;58(10):891-5. doi: 10.1016/s0002-9149(86)80005-4.
This investigation was undertaken in patients who had an acute myocardial infarction 12.6 +/- 0.4 months earlier to determine, using conventional methods, the nature of stroke volume changes during training regimens. Twenty-seven patients (mean age 52 +/- 2 years; rest ejection fraction 49 +/- 2%; New York Heart Association functional class I or II) and 9 normal, age-matched sedentary control subjects (mean age 50 +/- 1 years) exercised in the upright position on a bicycle ergometer. Stroke volume was measured by impedance cardiography at rest and after each workload. Ten patients (group A) had a stroke volume response similar to that of the normal sedentary subjects. In 8 patients (group B) the stroke volume increased initially, then decreased (more than 15%) at heart rates (HRs) greater than 100 to 105 beats/min. Nine patients (group C) had a flattened stroke volume response throughout exercise. Training HR determined by conventional methods corresponded to a maximal stroke volume in the normal subjects. Training HR in group A corresponded to a stroke volume that was maximal or near-maximal. Training HR in group B corresponded to a maximal or diminishing stroke volume. In group C, the training HR corresponded to a stroke volume no different from that at rest. Thus, training HR determined by conventional methods based solely on the chronotropic responses to exercise may place patients who have abnormal stroke volume responses to upright exercise in a situation during training sessions in which an inappropriately high HR, excessive fatigue or silent ischemia may develop.
本研究针对12.6±0.4个月前发生急性心肌梗死的患者展开，采用传统方法确定训练方案期间每搏输出量变化的性质。27例患者（平均年龄52±2岁；静息射血分数49±2%；纽约心脏协会心功能分级为I级或II级）和9名年龄匹配的正常久坐对照者（平均年龄50±1岁）在自行车测力计上进行直立位运动。在静息状态及每个工作负荷后，通过阻抗心动图测量每搏输出量。10例患者（A组）的每搏输出量反应与正常久坐受试者相似。8例患者（B组）的每搏输出量最初增加，然后在心率大于100至105次/分钟时下降（超过15%）。9例患者（C组）在整个运动过程中每搏输出量反应呈平台状。通过传统方法确定的训练心率在正常受试者中对应最大每搏输出量。A组的训练心率对应最大或接近最大的每搏输出量。B组的训练心率对应最大或递减的每搏输出量。在C组中，训练心率对应与静息时无差异的每搏输出量。因此，仅基于运动时变时反应通过传统方法确定的训练心率，可能会使对直立运动有异常每搏输出量反应的患者在训练期间处于可能出现不适当高心率、过度疲劳或无症状性缺血的情况。
