缺血性心脏病和扩张型心肌病患者心肺运动负荷研究

Peak Oxygen Uptake and Ventilatory Efficiency of Patients with Ischemic Heart Disease and Dilated Cardiomyopathy by Cardiopulmonary Exercise Testing

缺血性心脏病是心力衰竭的常见病因,峰运动VO2已经广泛用于心力衰竭患者心脏储备能力的评估。本研究通过心肺运动试验(Cardiopulmonary Exercise Test,CPET)心脏储备指数、通气效能指数来评价缺血性心脏病和扩张型心肌病的心衰患者运动心肺储备功能变化。选择170例心力衰竭病人(包括100例缺血性心脏病、70例扩张型心肌病患者)及75例正常人,进行症状限制性CPET。于运动前、运动高峰和运动后,分别测定心率和血压、峰氧耗量(PeakVO2)和VO2与预测最大VO2比例、无氧代谢阀、VE/VCO2斜率(通气效能指数)。结果显示,缺血性心脏病和扩张型心肌病患者左室射血分数相似,血压和静态心率无明显差异,运动心率明显下降,峰氧摄取量、无氧阈值、VE/VCO2斜率与扩张型心肌病患者相比有显著差别(P<0.05),峰心率明显低于扩张性心肌病。但峰氧耗量/预测峰氧耗量比例无明显差别。45例病人运动心率未达到标准。研究表明,缺血性心脏病患者心肺运动负荷测定的运动高峰VO2、无氧阀值及VE/VCO2斜率提示缺血性心脏病患者运动时通气效能和运动耐力下降比扩张型心肌病患者更为显著。

Studies in patients with heart failure have consistently shown a reduction in cardiac output and stroke volume at a given work rate and a lower peak heart rate when compared to normal subjects. Previous studies suggest that an attenuated exercise heart rate response and ventilation efficiency may be associated with chronic heart failure and with mortality. Heart rate response to exercise and ventilation function in patients with chronic heart failure due to ischemic heart disease or dilated cardiomyopathy remains a research issue. This paper studies the sinoatrial rate response and peak VO2 and ventilatory efficiency in heart failure patients with ischemic heart disease and dilated cardiomyopathy. 170 patients with chronic heart failure were selected, with 100 patients with ischemic heart disease, and 70 patients with dilated cardiomyopathy. All patients underwent modified Bruce treadmill exercise protocol. Exercise electrocardiogram and gas metabolic analysis were recorded. 75 normal subjects were taken as the control group. Heart rate on ECG response to treadmill exercise was determined as the percentage of target predicted Heart rate and the percentage of peak VO2 to predicted VO2. VE/VCO2 slop, anaerobic threshold AT were derived from cardiopulmonary exercise test. The patients with ischemic heart disease are older than those with dilated cardiomyopathy （P〈0.001）. Rest heart rate was found similar in both patients with ischemic or nonischemic heart disease. Peak heart rate response to peak exercise was reduced in patients with ischemic heart disease as compared with those with dilated cardiomyopathy（P=0.002）. 45 patients have chronotropic imcompetence（CI）, with less than 80% of predicted target heart rate, among which 28 patients are with ischemic heart disease and 17 patients with dilated cardiomyopathy （P〉0.05）. Age is correlated with peak VO2 in both patients with ischemic heart disease or dilated cardiomyopathy. But age is not correlated with percentage predicted VO2 in patients of both groups. Peak VO2 were reduced in patients with ischemic heart disease as compared with those with dilated cardiomyopathy （P=0.02）, predicted VO2 was similar for patients of both groups, ratio of peak VO2 to predicted MVO2 was also similar （P=0.38）. VE/VCO2 slop was increased （P=0.0001）. AT was reduced in patients with ischemic heart disease （P=0.016）. RQ ratio was not significant different between patients of two groups （P=1.0）. In patients with heart failure, coronary artery disease has a more significant influence on sino-atrial node function than in those without. Gas metabolism and exercise tolerance were significant limited as is similar to dilated cardiomyopathy. Respiratory Q ratio was similar between two groups. Peak VO2 was reduced in both ischemic heart disease and nonischmeic dilated cardiomyopathy. But there was no significant difference in MVO2/predicted VO2 between two groups. Ratio of MVO2 to predicted VO2 was similar. Heart rate response to exercise in patients with ischemic heart disease was more severely impaired than those with dilated cardiomyopathy. Ventilatory efficiency （VE/VCO2 slop） was significantly reduced in ischemic heart disease as compared with those with dilated cardiomyopathy. Chronotropic imcopletence was found in patients with ischemic heart disease and dilated cardiomyopathy. Appropriate medical and revascularization management or electrophysiology approach may modulate these disturbances in such patients.