Kraemer M D, Kubo S H, Rector T S, Brunsvold N, Bank A J
Department of Medicine, University of Minnesota Medical School, Minneapolis 55455.
J Am Coll Cardiol. 1993 Mar 1;21(3):641-8. doi: 10.1016/0735-1097(93)90096-j.
This study was conducted to determine the relations among exercise capacity and pulmonary, peripheral vascular, cardiac and neurohormonal factors in patients with chronic heart failure.
The mechanisms of exercise intolerance in heart failure have not been fully clarified. Previous studies have indicated that peripheral factors such as regional blood flow may be more closely associated with exercise capacity than cardiac function, whereas the role of pulmonary function has received less attention.
Fifty patients with stable heart failure underwent a comprehensive assessment that included a symptom-limited maximal cardiopulmonary exercise test, right heart catheterization, pulmonary function tests, neurohormonal levels, radionuclide ventriculography and forearm blood flow at rest and after 5 min of brachial artery occlusion. Univariate and stepwise linear regression analyses were used to relate peak exercise oxygen uptake to indexes of cardiac, peripheral vascular, pulmonary and neurohormonal factors both alone and in combination.
The mean ejection fraction was 19% and peak oxygen uptake was 16.5 ml/min per kg in this group of patients. By univariate analysis, there were no significant correlations between peak oxygen uptake and rest cardiac output, pulmonary wedge pressure, ejection fraction and pulmonary or systemic vascular resistance. In contrast, even in the absence of arterial desaturation during exercise, the forced expiratory volume in 1 s (r = 0.55, p < 0.001), forced vital capacity (r = 0.46, p < 0.01) and diffusing capacity for carbon monoxide (r = 0.47, p < 0.01) were all significantly associated with peak oxygen uptake. Peak postocclusion forearm blood flow (r = 0.45, p < 0.01), the corresponding minimal forearm vascular resistance (r = -0.56; p < 0.01) and plasma norepinephrine level at rest (r = -0.45; p < 0.01) were also significantly correlated with peak oxygen uptake. By multivariate analysis, minimal forearm vascular resistance and forced expiratory volume in 1 s were shown to be independently related to peak oxygen uptake, with a combined R value of 0.71. Other two-variate models included forced expiratory volume and plasma norepinephrine (R = 0.67) and forced expiratory volume and diffusing capacity (R = 0.65). Because forced vital capacity was highly correlated with forced expiratory volume in 1 s, it could be combined with the same variables to yield similar R values. Addition of any third variable did not improve these correlations.
In comparison with rest indexes of cardiac performance, measures of pulmonary function and peripheral vasodilator capacity were more closely associated with peak exercise oxygen uptake in patients with heart failure. Furthermore, the associations were independent of each other and together accounted for 50% of the variance in peak oxygen uptake. These data suggest that pulmonary and peripheral vascular adaptations may be important determinants of exercise intolerance in heart failure.
本研究旨在确定慢性心力衰竭患者运动能力与肺、外周血管、心脏及神经激素因素之间的关系。
心力衰竭患者运动不耐受的机制尚未完全阐明。既往研究表明，诸如局部血流等外周因素可能比心功能与运动能力的关系更为密切，而肺功能的作用则较少受到关注。
50例稳定型心力衰竭患者接受了全面评估，包括症状限制的最大心肺运动试验、右心导管检查、肺功能测试、神经激素水平检测、放射性核素心室造影以及静息和肱动脉阻断5分钟后的前臂血流测定。采用单因素和逐步线性回归分析，分别及联合分析运动峰值摄氧量与心脏、外周血管、肺及神经激素因素指标之间的关系。
该组患者的平均射血分数为19%，峰值摄氧量为16.5 ml/min per kg。单因素分析显示，峰值摄氧量与静息心输出量、肺楔压、射血分数及肺或体循环血管阻力之间无显著相关性。相反，即使运动期间无动脉血氧饱和度降低，1秒用力呼气量（r = 0.55，p < 0.001）、用力肺活量（r = 0.46，p < 0.01）和一氧化碳弥散量（r = 0.47，p < 0.01）均与峰值摄氧量显著相关。阻断后前臂血流峰值（r = 0.45，p < 0.01）、相应的最小前臂血管阻力（r = -0.56；p < 0.01）和静息血浆去甲肾上腺素水平（r = -0.45；p < 0.01）也与峰值摄氧量显著相关。多因素分析显示，最小前臂血管阻力和1秒用力呼气量与峰值摄氧量独立相关，联合R值为0.71。其他二元模型包括1秒用力呼气量与血浆去甲肾上腺素（R = 0.67）以及1秒用力呼气量与弥散量（R = 0.65）。由于用力肺活量与1秒用力呼气量高度相关，它可与相同变量联合得出相似的R值。添加任何第三个变量均未改善这些相关性。
与心脏功能的静息指标相比，肺功能和外周血管扩张能力指标与心力衰竭患者运动峰值摄氧量的关系更为密切。此外，这些关联相互独立，共同解释了峰值摄氧量变异的50%。这些数据表明，肺和外周血管适应性可能是心力衰竭患者运动不耐受的重要决定因素。
