Balaji S, Oslizlok P C, McKay C A, Allen M C, Case C L, Hewett K W, Gillette P C
South Carolina Children's Heart Center, Division of Pediatric Cardiology, Medical University of South Carolina, Charleston 29425.
Pacing Clin Electrophysiol. 1994 Feb;17(2):152-6. doi: 10.1111/j.1540-8159.1994.tb01366.x.
The effect of intravenous bolus doses (0.25, 0.5, 1.0 microgram) of isoproterenol on the QT and RR intervals was reviewed in a group of 34 children undergoing autonomic testing for syncope. Twenty-one patients had a positive orthostatic test and 13 were negative. The two groups (positive and negative) were compared. Baseline QT and RR intervals were similar. The RR interval was shortened by isoproterenol in both groups. Isoproterenol shortened the QT interval in the negative group (as seen in normal persons), but produced QT prolongation in the positive group, although neither reached statistical significance when compared to baseline within the respective group. Comparing the values for RR and QT at each dose of isoproterenol (including baseline) between the two groups showed a significant difference in the QT interval after the 1.0-microgram dose of isoproterenol. Thus children with orthostatic positive neurocardiogenic syncope showed a different QT response to beta-adrenergic stimulation. This lends support to the theory of altered beta-adrenergic sensitivity being present in children with neurocardiogenic syncope.
在一组34名因晕厥接受自主神经功能测试的儿童中，回顾了静脉推注不同剂量（0.25、0.5、1.0微克）异丙肾上腺素对QT间期和RR间期的影响。21例患者直立试验阳性，13例阴性。对两组（阳性和阴性）进行了比较。基线QT间期和RR间期相似。两组中异丙肾上腺素均使RR间期缩短。异丙肾上腺素使阴性组的QT间期缩短（如在正常人中所见），但使阳性组的QT间期延长，尽管与各自组内的基线相比，两者均未达到统计学显著性差异。比较两组在各剂量异丙肾上腺素（包括基线）下的RR和QT值，发现在1.0微克剂量的异丙肾上腺素后，QT间期存在显著差异。因此，直立试验阳性的神经心源性晕厥儿童对β-肾上腺素能刺激表现出不同的QT反应。这支持了神经心源性晕厥儿童存在β-肾上腺素能敏感性改变的理论。
