Cnota James F, Mays Wayne A, Knecht Sandra K, Kopser Shannon, Michelfelder Erik C, Knilans Timothy K, Claytor Randal P, Kimball Thomas R
Department of Pediatrics, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.
Med Sci Sports Exerc. 2003 Sep;35(9):1503-10. doi: 10.1249/01.MSS.0000084436.15808.52.
This study compared cardiac hemodynamics during supine cycle ergometry and dobutamine stress.
Thirty-two healthy volunteers (19 female, 13 male, 23.5 +/- 3.5 yr old) completed respective tests on separate days and in random order. Heart rate, blood pressure, and cardiac output were recorded at baseline and peak stress. Echocardiographic measures included left ventricular end-diastolic dimension, fractional shortening, heart rate corrected velocity of circumferential fiber shortening, end-systolic wall stress, and the difference between measured and predicted fiber shortening for measured wall stress.
Compared with peak exercise, dobutamine infusion resulted in lower cardiac output (12 +/- 2 vs 16 +/- 4 l x min(-1), P < 0.0001), heart rates (163 +/- 7 vs 175 +/- 12 beats x min(-1), P < 0.0001), and systolic blood pressure (160 +/- 22 vs 185 +/- 20 mm Hg, P < or = 0.0001). Echocardiography demonstrated smaller left ventricular end-diastolic dimension (4.2 +/- 0.7 vs 4.5 +/- 0.7 cm, P = 0.013), higher fractional shortening (0.55 +/- 0.07 vs 0.50 +/- 0.06%, P < 0.001), higher VCFc (2.07 +/- 0.36 vs 1.54 +/- 0.20 circs x s(-1), P < 0.001) higher VCFdiff (0.94 +/- 0.35 vs 0.48 +/- 0.20 circs x s(-1), P < 0.001), and lower end-systolic wall stress (25 +/- 11 vs 42 +/- 16 g x cm(-2), P < 0.001). The stress-velocity relationship during dobutamine demonstrated higher y-intercept and steeper slope, indicating greater load-independent contractility.
The cardiovascular adaptation to exercise and dobutamine stress differ significantly. Cardiac output during peak exercise is greater than during peak dobutamine secondary to increased heart rate and stroke volume. Despite a greater increase in contractility and decrease in afterload, a smaller increase in cardiac output during dobutamine stress may be secondary to limited ventricular preload.
本研究比较了仰卧位蹬车运动和多巴酚丁胺负荷试验期间的心脏血流动力学。
32名健康志愿者（19名女性，13名男性，年龄23.5±3.5岁）在不同日期以随机顺序完成各自的测试。在基线和负荷峰值时记录心率、血压和心输出量。超声心动图测量指标包括左心室舒张末期内径、缩短分数、心率校正的圆周纤维缩短速度、收缩末期壁应力以及实测壁应力下实测纤维缩短与预测纤维缩短之间的差值。
与运动峰值相比，多巴酚丁胺输注导致心输出量降低（12±2 vs 16±4 l·min⁻¹，P<0.0001）、心率降低（163±7 vs 175±12次·min⁻¹，P<0.0001）和收缩压降低（160±22 vs 185±20 mmHg，P≤0.0001）。超声心动图显示左心室舒张末期内径较小（4.2±0.7 vs 4.5±0.7 cm，P = 0.013）、缩短分数较高（0.55±0.07 vs 0.50±0.06%，P<0.001）、VCFc较高（2.07±0.36 vs 1.54±0.20周·s⁻¹，P<0.001）、VCFdiff较高（0.94±0.35 vs 0.48±0.20周·s⁻¹，P<0.001）以及收缩末期壁应力较低（25±11 vs 42±16 g·cm⁻²，P<0.001）。多巴酚丁胺负荷试验期间的应力-速度关系显示截距较高且斜率较陡，表明负荷依赖性收缩性更强。
心血管系统对运动和多巴酚丁胺负荷试验的适应性存在显著差异。运动峰值时的心输出量大于多巴酚丁胺峰值时的心输出量，这是由于心率和每搏输出量增加所致。尽管多巴酚丁胺负荷试验期间收缩性增加幅度更大且后负荷降低，但心输出量增加幅度较小可能是由于心室前负荷受限。
