Failure to decrease parasympathetic tone during upright tilt predicts a positive tilt-table test.
Failure to decrease parasympathetic tone during upright tilt predicts a positive tilt-table test.
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在直立倾斜期间未能降低副交感神经张力预示着倾斜台试验呈阳性。
DOI：
10.1016/s0002-9149(99)80623-7
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
Lerman,BB
中科院分区：
文献类型：
--
作者：
Lippman,N;Stein,KM;Lerman,BB
血管降压剂晕厥最常见的机制是通过增强交感神经张力激活心脏机械受体。由于自主神经系统在这种反应中的核心作用，我们假设交感和副交感神经系统（通过分析或心率变异性来评估）对直立应激的反应将区分倾斜桌反应阳性和阴性的患者。因此，我们评估了28例接受倾斜试验诊断血管降压性晕厥的患者。根据在仰卧和直立阶段（未输注异丙肾上腺素）获得的5分钟心电图样本，我们计算了平均RR间隔，反映了心脏交感神经和副交感神经的整体张力，以及RR间隔连续差异的均方根（RMSSD），这是与副交感神经张力相关的高频心率变异性的一种测量方法。11例倾斜反应阴性，17例倾斜反应阳性。两组在基线时无差异。在直立倾斜的反应中，两组的平均RR下降幅度相似。相反，RMSSD在直立倾斜阴性反应的患者中下降了36% (p = 0.05)，但在倾斜阳性反应的患者中没有显著变化。直立应激反应中RMSSD缺失或减少对预测阳性检测结果有100%的特异性和41%的敏感性。因此，直立倾斜时副交感神经张力退出失败（RMSSD评估）预示着积极的倾斜反应。这些结果表明，在这些患者中，交感神经张力的更大增加是维持直立反应的心率和血压所必需的，并且与交感神经张力增强可能是血管降压性晕厥发展的核心假设相一致。
The most frequently proposed mechanism for vasodepressor syncope is based on cardiac mechanoreceptor activation by augmented sympathetic tone. Because of the central role of the autonomic nervous system in this response, we hypothesized that the responses of the sympathetic ana parasympathetic nervous systems (as assessed by analysis or heart rate variability) to orthostatic stress would differentiate patients with a positive from those with a negative tilt-table response. We therefore evaluated 28 patients undergoing tilt-table testing for presumed vasodepressor syncope. Based on 5-minure electrocardiographic samples obtained during the supine and upright phases (without isoproterenol infusion), we computed the mean RR interval, reflecting integrated cardiac sympathetic and parasympathetic tone, as well as the root-mean-square of successive differences of the RR intervals (RMSSD), a measure of high-frequency heart rate variability that is correlated with parasympathetic tone. Eleven patients had a negative and 17 a positive tilt response. There were no differences between the groups at baseline. In response to upright tilt, the mean RR decreased by a similar magnitude in both groups. In contrast, RMSSD decreased by 36% (p = 0.05) in response to upright tilt in patients with a negative response, but did not change significantly in patients with a positive tilt response. Absence or a decrease in RMSSD in response to orthostatic stress had 100% specificity and 41% sensitivity for predicting a positive test result. Thus, failure of withdrawal of parasympathetic tone (as assessed by RMSSD) during upright tilt predicts a positive tilt response. These results suggest that a greater increase in sympathetic tone is necessary in these patients to maintain heart rate and blood pressure in response to orthostasis, and are consistent with the hypothesis that augmented sympathetic tone may be central to the development of vasodepressor syncope.