血管迷走性晕厥患者倾斜试验中自主神经功能异常的临床分析

Clinical analysis of autonomic nervous system dysfunction in patients with vasovagal syncope during head-up tilt test

目的 通过心率变异性分析,明确血管迷走性晕厥过程中的自主神经功能异常。方法 对2014年1月~2016年3月在武汉大学人民医院就诊、疑诊为血管迷走性晕厥的51例患者行直立倾斜试验,记录试验过程中的动态心电图并计算倾斜试验各阶段的15 min心率变异性指标,包括窦性心搏RR间期标准差（SDNN）、相邻NN差值的均方根（r MSSD）、差值〉50 ms相邻RR间期的百分比（p NN50）、低频功率（LF）、高频功率（HF）和平衡比（LF/HF）,分析上述指标在试验过程中的变化情况。结果 51例晕厥患者有24例含服硝酸甘油后出现阳性反应,包括心脏抑制型1例、血管抑制型7例、混合型16例,27例患者试验阴性。倾斜试验阳性组和阴性组在基础倾斜试验阶段的心率变异性指标差异无统计学意义,而在含服硝酸甘油后,阳性组的p NN50较阴性组显著升高（P=0.036）。与含服硝酸甘油前比较,阴性组的r MSSD、p NN50和HF均出现了显著下降（P〈0.01、P〈0.01、P=0.003）,LF/HF表现出升高的趋势,但差异无统计学意义（P=0.535）;而阳性组上述指标变化差异均无统计学意义。结论 血管迷走性晕厥患者在倾斜试验过程中存在自主神经调节功能异常,未能进行适当的自主神经调节,从而可能导致晕厥的发生。

Objective To investigate the abnormalities of antonomic nervous system in vasovagal syncope by analysis of heart rate variability（HRV）. Methods Fifty one patients with suspected vasovagal syncope admitted to Renmin Hospital of Wuhan University from January 2014 to March 2016 were enrolled. Head-up tilt test（HUTT） was performed in these patients and Holter ECG was monitored during the test. 15-min HRV indices including standard deviation of normal to normal intervals（SDNN）, the root mean square of successive differences between normal RR intervals（r MSSD）,percentage of normal-normal intervals that differ by 50 ms in the total number of RR intervals（p NN50）, low frequency（LF）, high frequency（HF） and ratio LF to HF（LF/HF） were calculated during different stages in HUTT and their changes were analyzed. Results Among the 51 enrolled patients with syncope, a total of 24 cases were HUTT positive after taking nitroglycerin（1 case with cardio-inhibitory reaction, 7 cases with vaso-inhibitory reaction, and 16 cases with mixed reaction）. And 27 cases were HUTT negative. No significant differences in HRV indices were found between positive group and negative group during basic test. However, after taking nitroglycerin, pNN50 in positive group became significantly higher than negative group（P = 0.036）. RMSSD, pNN50 and HF in HUTT negative group were all decreased sharply compared with before medication（P 0.01, P 0.01, P = 0.003）. LF/HF showed an increasing trend but with no significance（P = 0.535）. But in HUTT positive group, all these four indices were not changed.Conclusion The dysfunction of autonomic nervous system may exist during HUTT in patients with vasovagal syncope. The absence of proper antonomic regulation may cause the occurrence of syncope.