Bairey C N, de Yang L, Berman D S, Rozanski A
Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California 90048.
J Am Coll Cardiol. 1990 Oct;16(4):847-54. doi: 10.1016/s0735-1097(10)80332-8.
The recent development of the VEST, an ambulatory radionuclide detector, to measure left ventricular ejection fraction may enhance the detection of ischemia during daily activities in patients with coronary artery disease. The normal range and determinants of ejection fraction responses to stimuli other than physical exercise, however, are not adequately characterized. Therefore, ejection fraction responses to various activities were measured in 18 normal subjects utilizing the VEST. Uniform increases (greater than 5%) in ejection fraction were seen during physical exercise, uniform decreases were seen during cold pressor testing and modest changes (including decreases greater than 5%) were seen in ejection fraction during mental stress, micturition and hyperventilation. Different forms of stress produced significantly different changes in ejection fraction, even when values were controlled for changes in heart rate. Ventricular loading conditions in the form of enhanced blood pressure responses during mental stress may have contributed to the relatively smaller changes in ejection fraction compared with those during exercise. Subjects demonstrating a decrease in ejection fraction during mental stress did not differ from other subjects in hemodynamic reactivity during mental testing but did have evidence of increased parasympathetic tone during cold pressor and bicycle exercise testing. The results reveal that normal ejection fraction response differs among varying physiologic stimuli. These changes are in part related to changes in heart rate and blood pressure; however, other factors, such as neurohumoral regulation, may also play a role. These findings indicate that the patient's activity and the setting in which it occurs must be considered when interpreting ambulatory ejection fraction responses.
动态放射性核素检测仪VEST用于测量左心室射血分数，其最新进展可能会提高对冠心病患者日常活动期间缺血情况的检测。然而，除体育锻炼外，射血分数对其他刺激的正常范围及决定因素尚未得到充分描述。因此，利用VEST对18名正常受试者进行了各种活动时射血分数反应的测量。体育锻炼期间可见射血分数均匀增加（大于5%），冷加压试验期间可见均匀下降，精神应激、排尿及过度通气期间射血分数有适度变化（包括下降大于5%）。即使控制心率变化，不同形式的应激在射血分数上产生的变化仍显著不同。与运动期间相比，精神应激期间以血压反应增强形式出现的心室负荷情况可能导致射血分数变化相对较小。精神应激期间射血分数下降的受试者在精神测试期间的血流动力学反应性与其他受试者并无差异，但在冷加压及自行车运动测试期间确实有副交感神经张力增加的证据。结果显示，正常射血分数反应在不同生理刺激之间存在差异。这些变化部分与心率和血压变化有关；然而，其他因素，如神经体液调节，也可能起作用。这些发现表明，在解释动态射血分数反应时，必须考虑患者的活动及其发生环境。
