Leppo J A
Department of Nuclear Medicine, University of Massachusetts Medical Center, Worcester 01655-0243, USA.
J Nucl Cardiol. 1996 Nov-Dec;3(6 Pt 2):S22-6. doi: 10.1016/s1071-3581(96)90204-4.
In choosing a pharmacologic agent for stress testing, the clinician must keep a number of things in mind, such as the diagnostic utility of the agent or in what situations a vasodilator or catecholamine will be the better choice. Although all stress agents produce similar diagnostic accuracy for CAD, vasodilators have a higher cardiac uptake than catecholamines, and the addition of exercise improves the heart/background contrast ratios. With regard to physiologic comparisons, exercise or dobutamine will double coronary perfusion compared with baseline flow, but vasodilators produce a threefold or fourfold increase. The clinician should also keep in mind that adenosine will produce the shortest duration of hyperemia, whereas dobutamine and arbutamine produce a longer effect, and dipyridamole has the longest duration. If electrophysiologic considerations are important, exercise and catecholamines accelerate sinoatrial and atrioventricular conduction and are not typically associated with heart block. In contrast, adenosine can cause transient atrioventricular block, but this rarely occurs with dipyridamole. Clinical factors also must be considered. Although clinical utility of pharmacologic stress agents in the first 24 hours after infarction has not been demonstrated, the prognostic utility of vasodilators in the subsequent 2- to 4-day period has been shown. With patients with pulmonary disease (asthma) who do not have wheezing, dipyridamole can be used, but dobutamine or arbutamine should be used in patients with recent respiratory failure or bronchospasm before testing. In patients with left bundle branch block, vasodilators are the preferred stress agents rather than synthetic catecholamines or dynamic exercise. In the first crossover thallium imaging, there was good overall agreement in segmental perfusion comparing adenosine and dipyridamole, but there was a tendency for adenosine to detect more ischemia. The clinical significance (if any) for these findings has yet to be determined.
在选择用于负荷试验的药物时，临床医生必须牢记许多事项，例如该药物的诊断效用，或者在哪些情况下血管扩张剂或儿茶酚胺会是更好的选择。尽管所有负荷药物对冠心病的诊断准确性相似，但血管扩张剂的心脏摄取率高于儿茶酚胺，并且增加运动可改善心脏/本底对比度。关于生理学比较，与基线血流相比，运动或多巴酚丁胺可使冠状动脉灌注增加一倍，但血管扩张剂可使灌注增加三倍或四倍。临床医生还应牢记，腺苷产生的充血持续时间最短，而多巴酚丁胺和阿巴美丁的作用持续时间较长，双嘧达莫的持续时间最长。如果电生理因素很重要，运动和儿茶酚胺会加速窦房结和房室传导，通常不会导致心脏传导阻滞。相比之下，腺苷可导致短暂的房室传导阻滞，但双嘧达莫很少出现这种情况。临床因素也必须考虑在内。尽管尚未证实药物负荷剂在心肌梗死后最初24小时内的临床效用，但已显示血管扩张剂在随后2至4天的预后效用。对于没有喘息的肺部疾病（哮喘）患者，可以使用双嘧达莫，但对于近期有呼吸衰竭或支气管痉挛的患者，在检查前应使用多巴酚丁胺或阿巴美丁。对于左束支传导阻滞患者，血管扩张剂是首选的负荷剂，而不是合成儿茶酚胺或动态运动。在首次交叉铊显像中，比较腺苷和双嘧达莫时，节段灌注总体上有良好的一致性，但腺苷有检测到更多缺血的趋势。这些发现的临床意义（如果有的话）尚未确定。
