Wilson J R, Rayos G, Yeoh T K, Gothard P
Cardiology Division, Vanderbilt University Medical Center, Nashville, Tennessee 37232-2170, USA.
J Am Coll Cardiol. 1995 Aug;26(2):429-35. doi: 10.1016/0735-1097(95)80018-c.
The purpose of this study was to determine how often peak exercise oxygen consumption (VO2) misclassifies the severity of cardiac dysfunction in potential heart transplant candidates.
Cardiopulmonary exercise testing is being used to help select heart transplant candidates on the basis of the assumption that a low peak exercise VO2 indicates severe hemodynamic dysfunction and a poor prognosis. However, noncardiac factors, such as muscle deconditioning, can also influence exercise capacity. Therefore, peak exercise VO2 may overestimate the severity of cardiac dysfunction in some patients.
Hemodynamic and respiratory responses to maximal treadmill exercise were measured in 64 sequential patients undergoing evaluation for heart transplantation, all of whom had an ejection fraction < 35% and reduced peak exercise VO2 levels (mean [+/- SD] 13.3 +/- 2.7 ml/min per kg).
Twenty-eight (44%) of 64 patients exhibited a reduced cardiac output response to exercise and pulmonary wedge pressure > 20 mm Hg at peak exercise, consistent with severe hemodynamic dysfunction. Twenty-three patients (36%) exhibited a normal cardiac output response to exercise but a wedge pressure > 20 mm Hg at peak exercise, suggesting moderate hemodynamic dysfunction. Thirteen patients (20%) exhibited a normal cardiac output and wedge pressure < 20 mm Hg at peak exercise, suggesting mild hemodynamic dysfunction. Despite these markedly different hemodynamic responses, all three groups exhibited similar peak exercise VO2 levels (mild dysfunction 14.2 +/- 3.5 ml/min per kg, moderate dysfunction 13.9 +/- 2.7 ml/min per kg, severe dysfunction 12.4 +/- 2.1 ml/min per kg). A peak exercise VO2 level < 14 ml/min per kg, considered to reflect severe hemodynamic dysfunction, was observed in 18 of the patients with a normal cardiac output response to exercise, whereas 7 patients with severe hemodynamic dysfunction had a peak VO2 level > 14 ml/min per kg.
More than 50% of potential heart transplant candidates with a reduced peak exercise VO2 level exhibit only mild or moderate hemodynamic dysfunction during exercise. Hemodynamic responses to exercise should be directly measured in potential transplant candidates to confirm severe circulatory dysfunction.
本研究旨在确定在潜在的心脏移植候选者中，运动峰值耗氧量（VO₂）错误分类心脏功能障碍严重程度的频率。
心肺运动试验正被用于帮助选择心脏移植候选者，其依据的假设是低运动峰值VO₂表明存在严重的血流动力学功能障碍和不良预后。然而，非心脏因素，如肌肉失健，也会影响运动能力。因此，运动峰值VO₂在某些患者中可能高估了心脏功能障碍的严重程度。
对64例连续接受心脏移植评估的患者进行了最大运动平板试验时的血流动力学和呼吸反应测量，所有患者的射血分数均<35%且运动峰值VO₂水平降低（平均[±标准差]为13.3±2.7 ml/（min·kg））。
64例患者中有28例（44%）在运动时心输出量反应降低且运动峰值时肺楔压>20 mmHg，这与严重的血流动力学功能障碍一致。23例患者（36%）运动时心输出量反应正常，但运动峰值时楔压>20 mmHg，提示中度血流动力学功能障碍。13例患者（20%）运动峰值时心输出量和楔压均正常且<20 mmHg，提示轻度血流动力学功能障碍。尽管这些血流动力学反应明显不同，但三组的运动峰值VO₂水平相似（轻度功能障碍为14.2±3.5 ml/（min·kg），中度功能障碍为13.9±2.7 ml/（min·kg），重度功能障碍为12.4±2.1 ml/（min·kg））。在运动时心输出量反应正常的患者中有18例观察到运动峰值VO₂水平<14 ml/（min·kg），这被认为反映严重的血流动力学功能障碍，而7例严重血流动力学功能障碍的患者运动峰值VO₂水平>14 ml/（min·kg）。
超过50%的运动峰值VO₂水平降低的潜在心脏移植候选者在运动时仅表现出轻度或中度血流动力学功能障碍。对于潜在的移植候选者，应直接测量其运动时的血流动力学反应以确认严重的循环功能障碍。
