Waxman M B, Yao L, Cameron D A, Wald R W, Roseman J
Department of Medicine, University of Toronto, Ontario, Canada.
Am J Cardiol. 1989 Jan 1;63(1):58-65. doi: 10.1016/0002-9149(89)91076-x.
The ability of isoproterenol to induce symptoms and laboratory findings of a vasodepressor reaction was tested in 48 patients, ages 17 to 74, divided into 4 groups according to the reason for their referral. Group 1 comprised 12 patients with vasodepressor syncope, group 2 had 8 patients with syncope of unknown origin, group 3 included 11 patients with syncope due to seizures in 2 and ventricular tachycardia in 9, group 4 had 17 patients with various arrhythmias not associated with syncope. Isoproterenol boluses were administered starting at 2 micrograms and increased in 2-micrograms steps to a maximum of 8 micrograms at 0 degree and +60 degrees. The responses at 0 degrees were all normal. At +60 degrees a vasodepressor reaction consisting of syncope or near syncope, hypotension and bradycardia was produced by isoproterenol (mean dose 6.0 +/- 0.26 micrograms) in 8 patients from group 1 (66.6%), 4 from group 2 (50%), 0 from group 3 and 4 from group 4 (23.5%). Three of the 4 patients in group 4 had a remote history of classic vasodepressor syncope. The overall sensitivity and specificity of the test were 73 and 85%, respectively, while the predictive accuracy of a test with positive or negative outcome were 69 and 89%, respectively. Muscarinic receptor blockade with atropine in 4 patients prevented isoproterenol-induced bradycardia but not hypotension or symptoms of fainting. Beta-adrenergic receptor blockade with propranolol inhibited all aspects of the isoproterenol-induced faint. Thus, the administration of isoproterenol during a passive upright tilt may identify persons who suffer from or are prone to a vasodepressor reaction.
对48例年龄在17至74岁之间的患者进行了异丙肾上腺素诱发血管减压反应症状和实验室检查结果的能力测试，这些患者根据转诊原因分为4组。第1组包括12例血管减压性晕厥患者，第2组有8例不明原因晕厥患者，第3组包括11例晕厥患者，其中2例因癫痫发作，9例因室性心动过速，第4组有17例患有与晕厥无关的各种心律失常患者。从2微克开始静脉推注异丙肾上腺素，以2微克的步长增加，在0度和+60度时最大剂量为8微克。0度时的反应均正常。在+60度时，异丙肾上腺素（平均剂量6.0±0.26微克）在第1组的8例患者（66.6%）、第2组的4例患者（50%）、第3组的0例患者和第4组的4例患者（23.5%）中诱发了由晕厥或接近晕厥、低血压和心动过缓组成的血管减压反应。第4组的4例患者中有3例有典型血管减压性晕厥的既往史。该测试的总体敏感性和特异性分别为73%和85%，而阳性或阴性结果测试的预测准确性分别为69%和89%。4例患者用阿托品进行毒蕈碱受体阻滞可预防异丙肾上腺素诱发的心动过缓，但不能预防低血压或晕厥症状。用普萘洛尔进行β肾上腺素能受体阻滞可抑制异丙肾上腺素诱发晕厥的所有方面。因此，在被动直立倾斜期间给予异丙肾上腺素可识别患有或易患血管减压反应的人。
