McElroy P A, Janicki J S, Weber K T
Department of Medicine, Michael Reese Hospital, University of Chicago, Illinois 60616.
J Am Coll Cardiol. 1988 Jan;11(1):94-9. doi: 10.1016/0735-1097(88)90172-6.
Rate-responsive cardiac pacing requires a sensitive physiologic variable that is closely correlated with the heart rate-oxygen uptake relation, particularly in patients with heart failure whose cardiac output response to exercise is more dependent on heart rate. Accordingly, the heart rate response to upright exercise was measured in 81 patients with heart failure or hypertension, or both, and in 27 normal subjects. Oxygen uptake (VO2), minute ventilation (VE), cardiac output, right heart pressures and the mixed venous temperature, oxygen saturation (SvO2) and pH were analyzed throughout exercise. Linear regression analysis of these variables with heart rate revealed the following: 1) There was a highly linear heart rate-VO2 relation in each subject (the average slope of this relation was greater [p less than 0.05] in patients with more severe failure). 2) VE was highly correlated with exercise heart rate, and its slope was not different between normal subjects and patients. 3) Mixed venous temperature and pH were poor predictors of exercise heart rate, particularly at low or moderate levels of work; however, SvO2 was highly correlated with heart rate for all levels of work. Thus, in normal subjects and patients with heart failure or hypertension, or both, heart rate increases linearly with isotonic leg exercise. Minute ventilation and mixed venous oxygen saturation are highly correlated with this response and may serve as potential sensors for rate-responsive pacemakers.
频率适应性心脏起搏需要一个敏感的生理变量，该变量与心率-摄氧量关系密切相关，尤其是在心力衰竭患者中，其心输出量对运动的反应更依赖于心率。因此，对81例心力衰竭或高血压患者或两者兼具的患者以及27名正常受试者进行了直立运动时心率反应的测量。在整个运动过程中分析了摄氧量（VO2）、分钟通气量（VE）、心输出量、右心压力以及混合静脉温度、氧饱和度（SvO2）和pH值。对这些变量与心率进行线性回归分析得出以下结果：1）每个受试者的心率与VO2之间存在高度线性关系（在病情较重的患者中，这种关系的平均斜率更大[p<0.05]）。2）VE与运动心率高度相关，其斜率在正常受试者和患者之间无差异。3）混合静脉温度和pH值对运动心率的预测能力较差，尤其是在低或中等运动水平时；然而，在所有运动水平下，SvO2与心率高度相关。因此，在正常受试者以及心力衰竭或高血压患者或两者兼具的患者中，等张腿部运动时心率呈线性增加。分钟通气量和混合静脉血氧饱和度与这种反应高度相关，可能作为频率适应性起搏器的潜在传感器。
