研究背景：

血管迷走性晕厥（vasovagal syncope, VVS）是由自主神经功能异常引发的神经反射性晕厥，是临床最常见的晕厥类型。据统计20%~40%的人群在一生中至少经历一次VVS的发作。在临床中，VVS在急诊晕厥患者中的占比可达40%~60%，在儿童不明原因晕厥的占比高达80%。VVS患者预后良好，但反复的晕厥发作可引发患者巨大的心理困扰与日常生活能力下降。因此，积极的诊疗策略对改善患者生活质量十分必要。

典型VVS由交感神经异常减退和/或迷走神经异常激活引发，自主神经异常引起心率和血压的骤降，致使全身循环灌注尤其是脑灌注不足是患者意识丧失的直接原因，此类患者临床特征显著，可依据患者病史特点做出诊断。但不典型VVS患者的诊断困难，倾斜试验等辅助检查的诊断价值有限，缺少提供直接诊断依据的指标或证据。在VVS治疗方面，患者教育和生活习惯改善等非药物治疗是VVS治疗的基础，药物治疗及起搏器治疗应根据临床谨慎考虑。相较于以上传统治疗，心脏去神经消融治疗直接靶向心脏表面神经节丛，远期治疗成功率在90%以上，解决该术式的患者选择、消融策略等问题是应用和推广该治疗方案的基础。

第一部分：

心率减速力与连续心率减速力在血管迷走性晕厥诊断中的应用

目的：探讨VVS患者与健康人相比发病的危险因素，评估自主神经相关指标对VVS的诊断价值；分析VVS患者自主神经调控心率变化的生理特点，寻求对该疾病更多的认知。

方法：连续入选2017年8月至2020年6月在我院就诊的188名明确诊断为VVS的患者，同时入选132名健康人作为对照组。比较两组的基线资料，24小时Holter检查数据，心率减速力（heart rate deceleration capacity, DC），连续心率减速力（heart rate deceleration runs, DRs）等自主神经评估指标，应用Logistics回归分析评估VVS患者与健康人相比发病的危险因素。

结果：VVS患者组与健康对照组相比，DC值显著较高（10.63±2.1 ms vs. 6.58±1.7 ms, P＜0.001）；DR6-10显著较低（P＜0.01）。多因素回归分析显示：DC (OR 1.541; 95% CI 1.173-2.024; P = 0.01)，极长DR（very long DR, VLDR）即DR8-10之和(OR 5.614; 95% CI 1.486-9.771; P＜0.001)和最慢心率 (OR = 0.946, 95% CI 0.897–0.998, P = 0.041)是VVS发病的独立危险因素。DC、DC结合最慢心率及DC结合VLDR等多种模型被应用于VVS诊断，其中，DC和DC结合VLDR模型的诊断效能最高，二者的曲线下面积（area under curve, AUC）无统计学差异(P = 0.216)。DC结合VLDR模型的诊断特异性显著高于DC模型(0.879 vs. 0.681, P＜0.01)。

结论：DC结合DRs应用于VVS患者中将有助于定量评估VVS患者的迷走神经调控活动，也有助于促进VVS的诊断。

第二部分：

心率减速力与连续心率减速力在难治性血管迷走性晕厥去神经消融中的应用

目的：探讨自主神经活动评估指标与难治性VVS患者消融术后复发的相关性。

方法：连续入选2017年8月至2020年6月在我院行心脏神经消融手术的难治性VVS患者147例,比较消融术后复发与未复发组患者的心率变异性、心率减速力、连续心率减速力的差异性。

结果：与未复发组相比，1)复发组患者男性比例更少（50.1% vs 26.3%, p=0.012）；患者收缩压更低（122±14mmHg vs 115±16mmHg, p=0.004）；2)复发组患者的全天DC（10.3±3.1ms vs 8.3±4.0ms, p=0.008），日间DC（10.1±3.1ms vs 8.0±4.1ms, p=0.001），夜间DC（11.5ms±3.3ms vs 9.8±3.7ms, p=0.02）均显著较低；3) 两组患者的心率变异性分析——时域分析和频域分析相关指标均无显著性差异；两组患者的连续心率减速力指标DR1-10均未见显著性差异。多因素logistic回归分析显示，性别、收缩压及日间DC是消融术后晕厥/晕厥前兆复发的独立危险因素。

结论：复发组患者的DC显著低于未复发组患者，表明VVS患者间存在迷走神经活动的差异；两组间的HRV和DRs指标则无显著性差异，也提示多种自主神经功能评估方法之间各有优势，相互补充。

Background:

Vasovagal syncope (VVS) is a neuroreflex syncope caused by abnormal autonomic nervous function, which is the most common type of syncope in clinic. It is estimated that 20% to 40% of the population will experience at least one episode of VVS in their lifetime. VVS accounts for 40%~60% of emergency syncope patients and up to 80% of children with unexplained syncope. The prognosis for VVS patients is good, but repeated episodes of syncope can cause significant psychological distress and reduce patients' ability to perform daily activities. Therefore, active diagnosis and treatment strategies are necessary to improve patients' quality of life.

Typical VVS are triggered by abnormal sympathetic reduction and/or abnormal activation of the vagus nerve, and abnormal autonomic nerve causes a sudden decrease in heart rate and blood pressure, resulting in systemic circulatory hypoperfusion, especially cerebral hypoperfusion, which is the direct cause of the loss of consciousness in the patients. Typical VVS patients have significant clinical features and can be diagnosed according to the characteristics of the patient's medical history. However, the diagnosis of patients with atypical VVS is difficult, and the diagnostic value of auxiliary examinations such as tilt test is limited, lacking indicators or evidence to provide direct diagnostic basis. In the treatment of VVS, non-drug therapy such as patient education and improvement of living habits is the basis of VVS treatment, and drug therapy and pacemaker therapy should be carefully considered according to clinical conditions. Compared with the above traditional treatments, cardioneuroablation therapy directly targets the ganglion plexus on the surface of the heart, and the long-term treatment success rate is more than 90%. Solving the problems of patient selection and ablation strategy of this procedure is the basis for the application and promotion of this treatment program.

This study aimed to investigate the risk factors of VVS patients compared with healthy people, and to evaluate the diagnostic value of autonomic nervous system evaluation indexes for VVS. To analyze the physiological characteristics of the autonomic nerve regulating the heart rate change in VVS patients, so as to seek more understanding of this disease. To investigate autonomic nerve assessment indexes in relation to ablation and recurrence in cardioneuroablation patients with refractory vasovagal syncope.

Part one:

Application of deceleration capacity combined with deceleration runs in diagnosis of vasovagal syncope

Objectives This study aimed to investigate the risk factors of VVS patients compared with healthy people, and to evaluate the diagnostic value of autonomic nervous system evaluation indexes for VVS. To analyze the physiological characteristics of the autonomic nerve regulating the heart rate change in VVS patients, so as to seek more understanding of this disease.

Methods A total of 188 patients with definite diagnosis of VVS admitted to our hospital from August 2017 to June 2020 were continuously enrolled, and 132 healthy subjects were included as control group. Baseline data, 24-hour Holter test data, heart rate deceleration capacity (DC) and heart rate deceleration runs (DRs) of the two groups were compared. The risk factors of VVS patients compared with healthy people were evaluated by Logistics regression analysis.

Results VVS patients had higher DC (10.63±2.1 ms vs. 6.58±1.7 ms, P＜0.001) and lower DR6-10 than controls. In multivariate logistic regression, DC (OR 1.541; 95% CI 1.173-2.024; P = 0.01), VLDR (OR 5.614; 95% CI 1.486-9.771; P＜0.001) and the minimum heart rate (OR = 0.946, 95% CI 0.897–0.998; P = 0.041) were independent predictors for syncope. Various models, such as DC, DC combined minimum heart rate and DC combined VLDR, were applied to the diagnosis of VVS. Among them, the area under curve (AUC) analysis showed similar values when comparing DC alone and DC combined with VLDR (P = 0.216). The specificity of DC combined with the VLDR was significantly higher than that of the DC-only model (0.879 vs. 0.681, P＜0.01).

Conclusion In VVS patients, DC combined with DRs revealed a better ability for quantification of vagal modulation, thus may further improve VVS diagnosis.

Part two:

Application of deceleration capacity combined with deceleration runs in cardioneuroablation in patients with refractory vasovagal syncope

Objectives This study was to investigate autonomic nerve assessment indexes in relation to ablation and recurrence in cardioneuroablation patients with refractory vasovagal syncope.

Methods One hundred and forty-seven patients with refractory VVS who underwent cardiac nerve ablation in our hospital from August 2017 to June 2020 were consecutively enrolled, and the differences of heart rate variability, DC and DRs were compared between patients with and without recurrence after ablation.

Results 1) Compared with the non-recurrence group, the proportion of male patients in the recurrence group was lower (50.1% vs 26.3%, p=0.012); Patients had lower systolic blood pressure (122±14mmHg vs 115±16mmHg, p=0.004). 2) Compared with the non-recurrence group, the all-day DC (10.3±3.1ms vs 8.3±4.0ms, p=0.008) and daytime DC (10.1±3.1ms vs 8.0±4.1ms, p=0.001) in the recurrence group, The night DC (11.5±3.3ms vs 9.8±3.7ms, p=0.02) was significantly lower. 3) There was no significant difference in the relevant indexes of heart rate variability in time domain analysis and frequency domain analysis between the two groups. There was no significant difference in heart rate deceleration runs between the two groups. Multiple logistic regression analysis showed that gender, systolic blood pressure and daytime DC were independent risk factors for syncope/presyncope recurrence after ablation.

Conclusion The DC of patients in the relapsed group was significantly lower than that in the non-relapsed group, indicating that there were differences in vagus nerve activity among patients with VVS. There was no significant difference in HRV and DRs between the two groups, suggesting that various methods of autonomic nervous function assessment have their own advantages and complement each other.