Böttcher M, Czernin J, Sun K T, Phelps M E, Schelbert H R
Department of Molecular and Medical Pharmacology, UCLA School of Medicine 90095-1735, USA.
J Nucl Med. 1995 Nov;36(11):2016-21.
Stress testing with intravenous injection of dipyridamole is frequently used for noninvasive detection of coronary artery disease (CAD) with PET or SPECT. Dietary intake of caffeinated food, beverages or medication might alter both resting and dipyridamole-induced hyperemic blood flow, thereby compromising the diagnostic sensitivity of dipyridamole stress testing.
To quantify the effect on myocardial blood flow at rest and during intravenous injection of dipyridamole, 12 healthy volunteers (mean age 27 +/- 6 yr) with low risk for CAD were studied with dynamic PET and a tracer kinetic model for 13N-ammonia after 24 hr of caffeine abstinence and after caffeine intake.
Caffeine tended to increase the rate pressure product from 6873 +/- 1494 to 7566 +/- 1102 (p = 0.051), whereas resting myocardial blood flow remained unchanged (0.61 +/- 0.13 versus 0.58 +/- 0.07 ml/g/min, p = ns). The heart rate response to dipyridamole was inversely related to serum caffeine levels. Hyperemic blood flow (2.01 +/- 0.46 versus 1.31 +/- 0.0.38 ml/g/min; p < 0.001) and flow reserve (3.4 +/- 0.8 versus 2.3 +/- 0.7; p < 0.001) were inversely related to the caffeine dose. Coronary vascular resistance at rest tended to increase (132 +/- 32 versus 147 +/- 25 mmHg/ml/g/min; p = 0.06), whereas minimal coronary vascular resistance was significantly higher after caffeine (41 +/- 9 to 69 +/- 25 mmHg/ml/g/min; p < 0.01).
Caffeine intake alters the coronary vasomotor tone at rest, which might lower the threshold for ischemic events in patients with CAD. It reduces hyperemic blood flow and flow reserve and the dipyridamole-induced increase in heart rate in a dose-dependent fashion. These findings emphasize the importance of carefully screening patients for intake of caffeinated food, beverages or medication prior to dipyridamole stress testing.
静脉注射双嘧达莫进行负荷试验常用于通过PET或SPECT对冠状动脉疾病（CAD）进行无创检测。摄入含咖啡因的食物、饮料或药物可能会改变静息状态及双嘧达莫诱导的充血性血流，从而降低双嘧达莫负荷试验的诊断敏感性。
为量化静息及静脉注射双嘧达莫期间对心肌血流的影响，对12名CAD低风险的健康志愿者（平均年龄27±6岁）在戒咖啡因24小时后及摄入咖啡因后，采用动态PET及13N-氨示踪动力学模型进行研究。
咖啡因倾向于使心率血压乘积从6873±1494增加至7566±1102（p = 0.051），而静息心肌血流保持不变（0.61±0.13对0.58±0.07 ml/g/min，p =无统计学意义）。对双嘧达莫的心率反应与血清咖啡因水平呈负相关。充血性血流（2.01±0.46对1.31±0.0.38 ml/g/min；p < 0.001）及血流储备（3.4±0.8对2.3±0.7；p < 0.001）与咖啡因剂量呈负相关。静息时冠状动脉血管阻力倾向于增加（132±32对147±25 mmHg/ml/g/min；p = 0.06），而咖啡因摄入后最小冠状动脉血管阻力显著更高（41±9至69±25 mmHg/ml/g/min；p < 0.01）。
摄入咖啡因会改变静息时的冠状动脉血管舒缩张力，这可能会降低CAD患者缺血事件的阈值。它以剂量依赖的方式降低充血性血流和血流储备以及双嘧达莫诱导的心率增加。这些发现强调了在双嘧达莫负荷试验前仔细筛查患者摄入含咖啡因食物、饮料或药物情况的重要性。
