Raviele A, Gasparini G, Di Pede F, Delise P, Bonso A, Piccolo E
Divisione Cardiologica, Ospedale Umberto I, Mestre, Venezia.
G Ital Cardiol. 1990 Mar;20(3):185-94.
The vaso-vagal nature of syncopes which remained unexplained despite full clinical and electrophysiological investigation was evaluated by means of 60 degrees head-up tilt test for 60 minutes. Thirty patients (16 men and 14 women, mean age 63.6 years, 19 with and 11 without organic heart disease) with 1 to 28 (mean 5.1) episodes of syncope of unknown origin were studied together with 11 asymptomatic control subjects. Head-up tilt test was considered positive if syncope developed in association with hypotension and/or bradycardia. During baseline head-up tilt 15 patients (50%) showed a positive test, with vasodepressor response (marked hypotension without marked bradycardia) in 10 cases and with mixed response (marked hypotension with marked bradycardia) in 5 cases. None of the control subjects became symptomatic during the test. Mean time to syncope was 24.9 minutes. Baseline head-up tilt test was reproducibly positive in 10 out of 14 patients (71%). Eight of these 10 patients underwent serial head-up tilt tests after atropine (0.04 mg/Kg i.v. in 1 minute), propranolol (0.2 mg/Kg i.v. in 3 minutes) and etilefrin (15-30 mg/day orally for 2-3 days) to determine the pathogenesis of vaso-vagal syncope. Atropine prevented tilt-induced syncope in 3 out of 7 patients (43%), propranolol in 2 out of 7 (29%) and etilephrine in 6 out of 6 (100%). Seven patients were chronically treated with drugs selected on the basis of acute drug testing. One patient-responder to atropine received transdermal scopolamine and the other 6 received etilephrine. None of these 7 patients had syncopal recurrences or death during a mean follow-up of 7.7 months, except 1 who experienced another episode of syncope after having discontinued etilephrine 4 months before. These results suggest that: 1) head-up tilt is a very sensitive and highly specific test to unmask susceptibility to vaso-vagal reaction in patients with syncope of unknown origin; 2) withdrawal of alpha-sympathetic stimulation is the principal mechanism responsible for vasodilation and syncope during head-up tilt; 3) alpha-sympathomimetic agents, such as etilephrine, are effective in preventing spontaneous episodes of vaso-vagal syncope during a short-term follow-up.
对于那些尽管经过全面临床和电生理检查仍无法解释的晕厥，通过60度头高位倾斜试验60分钟来评估其血管迷走性本质。研究了30例不明原因晕厥发作1至28次（平均5.1次）的患者（16例男性和14例女性，平均年龄63.6岁，19例有器质性心脏病，11例无器质性心脏病），并与11名无症状对照者一起进行研究。如果晕厥与低血压和/或心动过缓同时发生，则头高位倾斜试验被认为是阳性。在基础头高位倾斜期间，15例患者（50%）试验呈阳性，其中10例为血管减压反应（显著低血压但无显著心动过缓），5例为混合反应（显著低血压伴显著心动过缓）。在试验过程中，没有一名对照者出现症状。晕厥的平均发作时间为24.9分钟。14例患者中有10例（71%）基础头高位倾斜试验结果可重复呈阳性。这10例患者中的8例在静脉注射阿托品（0.04 mg/Kg，1分钟内）、普萘洛尔（0.2 mg/Kg，3分钟内）和乙苯福林（15 - 30 mg/天，口服2 - 3天）后进行了系列头高位倾斜试验，以确定血管迷走性晕厥的发病机制。阿托品可预防7例患者中的3例（43%）倾斜诱发的晕厥，普萘洛尔可预防7例中的2例（29%），乙苯福林可预防6例中的6例（100%）。7例患者根据急性药物试验结果选择药物进行长期治疗。1例对阿托品有反应的患者接受了透皮东莨菪碱治疗，另外6例接受了乙苯福林治疗。在平均7.7个月的随访期间，这7例患者均未出现晕厥复发或死亡，除了1例在停用乙苯福林4个月后又发生了一次晕厥。这些结果表明：1）头高位倾斜试验对于揭示不明原因晕厥患者对血管迷走反应的易感性是一项非常敏感且高度特异的检查；2）α - 交感神经刺激的撤离是头高位倾斜期间血管扩张和晕厥的主要机制；3）α - 拟交感神经药物，如乙苯福林，在短期随访期间可有效预防血管迷走性晕厥的自发发作。
