Tischler M D, Niggel J, Borowski D T, LeWinter M M
Cardiology Unit, Medical Center Hospital of Vermont, Burlington 05401.
J Am Coll Cardiol. 1993 Sep;22(3):751-7. doi: 10.1016/0735-1097(93)90187-6.
The aim of this study was to identify dynamic predictors of exercise duration in patients with systolic left ventricular dysfunction and to test the hypothesis that left ventricular shape is an independent determinant of exercise duration in these patients.
Measurements of left ventricular volumes and ejection fraction at rest do not predict exercise capacity in patients with systolic left ventricular dysfunction. Left ventricular shape at rest has been reported to be an independent determinant of exercise duration in these patients. The significance of alterations in left ventricular shape that occur during dynamic exercise has not been investigated.
Twenty-one patients with a documented ejection fraction < 40% performed symptom-limited graded upright bicycle exercise with simultaneous quantitative two-dimensional echocardiography. End-diastolic volume, end-systolic volume, stroke volume, ejection fraction and sphericity index were measured at rest and peak exercise.
Eleven patients exercised beyond stage II (6 min, 50 W), averaging 8.9 +/- 1.9 min; 10 patients were unable to complete stage II, averaging 4.9 +/- 0.9 min. No patient developed clinical evidence of ischemia during the exercise period. Of the echocardiographic variables considered, only end-systolic and end-diastolic sphericity indexes at peak exercise (r = 0.809 and 0.711, respectively) and the change in end-systolic sphericity index during exercise (r = 0.697) were strongly correlated with exercise duration.
Conventional descriptors of left ventricular function are poor predictors of exercise capacity. Dynamic changes in heart shape correlate strongly with exercise duration and may be important determinants of exercise capacity in patients with systolic left ventricular dysfunction.
本研究旨在确定收缩期左心室功能不全患者运动持续时间的动态预测因素，并检验左心室形态是这些患者运动持续时间的独立决定因素这一假设。
静息时左心室容积和射血分数的测量不能预测收缩期左心室功能不全患者的运动能力。据报道，静息时左心室形态是这些患者运动持续时间的独立决定因素。动态运动期间左心室形态改变的意义尚未得到研究。
21名记录射血分数<40%的患者进行症状限制的分级直立自行车运动，同时进行定量二维超声心动图检查。在静息和运动峰值时测量舒张末期容积、收缩末期容积、每搏输出量、射血分数和球形指数。
11名患者运动超过II期（6分钟，50瓦），平均8.9±1.9分钟；10名患者无法完成II期，平均4.9±0.9分钟。运动期间无患者出现缺血的临床证据。在考虑的超声心动图变量中，只有运动峰值时的收缩末期和舒张末期球形指数（分别为r = 0.809和0.711）以及运动期间收缩末期球形指数的变化（r = 0.697）与运动持续时间密切相关。
左心室功能的传统描述指标对运动能力的预测较差。心脏形态的动态变化与运动持续时间密切相关，可能是收缩期左心室功能不全患者运动能力的重要决定因素。
