Efremov Kristian, Brisinda Donatella, Venuti Angela, Iantorno Emilia, Cataldi Claudia, Fioravanti Francesco, Fenici Riccardo
Catholic University of the Sacred Heart, Biomagnetism Center, Clinical Physiology , Rome , Italy.
Open Heart. 2014 Jun 14;1(1):e000063. doi: 10.1136/openhrt-2014-000063. eCollection 2014.
The aim of this study was to determine whether or not heart rate variability (HRV) analysis during the first 20 min of head-up tilt testing could predict whether patients will develop syncope after nitroglycerine administration.
64 patients with previous loss of consciousness underwent head-up tilt testing with the Italian protocol, which involves the administration of nitroglycerine after 20 min of tilt. HRV parameters were analysed from 5 min intervals selected during pretest supine rest (phase 1), the first 5 min (phase 2) and the last 5 min (phase 3) of passive 20 min of tilting, prior to the administration of nitroglycerine. Differences in power (ms(2)) of the spectral components between the various phases of tilting were calculated for each patient and expressed as Δ.
20 patients (group 1, 9 women, mean age 43.2±24.5 years) had a syncope during tilt testing after nitroglycerine, while the other 44 (group 2, 24 women, mean age 41±20.5 years) did not. In group 1, the HRV spectral parameters high frequency (HF) and total power (TP) had a significant decrement from phases 2 to 3 (p=0.012 and 0.027, respectively), while in group 2 the average HF and TP values did not change. The Δ of spectral parameters between phases 2 and 3 were able to differentiate between the two groups and to predict syncope after nitroglycerine administration (p<0.05).
HRV analysis within the first 20 min of passive tilting demonstrated that patients with nitroglycerine-induced syncope are characterised by a progressive decrement of parasympathetic activity, which does not occur in patients with a negative response to nitroglycerine. If confirmed on a wider population, HRV analysis could replace nitroglycerine administration and shorten the duration of the tilt test.
本研究旨在确定头高位倾斜试验最初20分钟期间的心率变异性（HRV）分析能否预测患者在服用硝酸甘油后是否会发生晕厥。
64例既往有过意识丧失的患者按照意大利方案进行头高位倾斜试验，该方案包括在倾斜20分钟后给予硝酸甘油。在服用硝酸甘油之前，于试验前仰卧休息（阶段1）、被动倾斜20分钟的前5分钟（阶段2）和最后5分钟（阶段3）期间，每隔5分钟分析HRV参数。计算每位患者在倾斜各阶段之间频谱成分的功率差异（毫秒²），并表示为Δ。
20例患者（第1组，9名女性，平均年龄43.2±24.5岁）在服用硝酸甘油后的倾斜试验期间发生晕厥，而其他44例患者（第2组，24名女性，平均年龄41±20.5岁）未发生晕厥。在第1组中，HRV频谱参数高频（HF）和总功率（TP）从阶段2到阶段3有显著下降（分别为p = 0.012和0.027），而在第2组中，平均HF和TP值没有变化。阶段2和阶段3之间频谱参数的Δ能够区分两组，并预测服用硝酸甘油后的晕厥情况（p<0.05）。
被动倾斜最初20分钟内的HRV分析表明，硝酸甘油诱发晕厥的患者具有副交感神经活动逐渐下降的特征，而对硝酸甘油反应阴性的患者则不会出现这种情况。如果在更广泛的人群中得到证实，HRV分析可以取代硝酸甘油给药，并缩短倾斜试验的持续时间。
