肺叶切除术后自主神经在房颤中的作用

目的探讨自主神经在肺叶切除术后房颤发生中的作用。方法对281例60岁以上接受肺叶或全肺切除术的患者进行术后连续96h的动态心电图监测,对出现房颤患者在房颤发生前2h的心率变异性指标进行分析,并与同期性别、年龄相匹配未发生房颤患者相应时间段的心率变异性指标进行对比研究,分析交感神经张力与迷走神经张力在房颤发生前的变化。结果 281例肺切除患者术后有48例患者出现房颤,发生率17.1%;房颤组及对照组的病例基本资料无明显统计学差异,房颤组在房颤发生前2h反映迷走神经张力的指标SDNN、rMSSD、pNN50、HF明显增高,而反映交感/副交感神经平衡的指标LF/HF与对照组降低无统计学差异;而在房颤发生前5min SDNN、rMSSD、pNN50、HF明显增高,而LF/HF比值明显降低,表明迷走神经张力明显增高。结论肺叶切除术后的房颤发生前心率变异性存在明显增高的表现,肺叶切除术后交感神经张力明显增高的背景下迷走神经张力竞争性增高可能是导致房颤发生的重要机制。     

自主神经在阵发性心房颤动发生中的作用

目的 探讨自主神经在阵发性心房颤动发生中的作用。方法 分析31例阵发性房颤患者47次房颤（〉30s）发作前动态心电图心率变异性时域和频域指标。患者分为器质性心脏病组（19例）和非器质性心脏病组（12例）。根据房颤发作前频域指标变化，将阵发性房颤分为3组：房颤发作前心率变异性频域指标低频（LF）成分增加，LFIHF比例增加为交感神经介导房颤，房颤发作前心率变异性频域指标高频（HF）成分增加，LF／HF比例减小为迷走神经介导房颤，其余的为未分类房颤。结果 器质性心脏病组房颤发作28次，其中交感神经介导房颤17次（60．7％），非器质性心脏病组房颤发作19次，迷走神经介导房颤12次（63．2％）。结论 自主神经在房颤的发作中起着重要的作用，器质性心脏病中的阵发性房颤多为交感神经介导房颤。非器质性心脏病中的阵发性房颤多为迷走神经介导房颤。     

自主神经系统在心房颤动中的作用和联系

心房颤动（房颤）在临床上极为常见,目前心房颤动的机制尚未阐明,其中自主神经系统在房颤的发生、维持、终止和决定室性心律上是一个潜在的强大的调节因素。存在于中枢、神经节、外周组织、细胞和亚细胞水平的交感和副交感系统的复杂相互作用都能够改变心脏的传导性和不应期,较为重要的是分布于心脏的自主神经的调节作用能引起心房节律的改变以及影响触发活动的产生和类型,所有这些变化都能引发和维持房颤。本文就心脏自主神经系统在房颤发生发展过程中的可能的作用机制及相互联系作一综述,为基础研究和临床实践中对房颤的机制研究和治疗提供参考依据和理论基础。     

胸腔镜辅助与开胸肺叶切除术后房颤发生率和心率变异性的比较

目的 比较经胸腔镜与开胸肺叶切除手术后房颤发生率和术后心率变异性的差别。方法 60岁以上接受胸腔镜下肺叶切除术（胸腔镜组,n=112）与既往数据库中接受开胸肺叶切除术患者(开胸组,n=112),在性别、年龄等基础临床资料与其相匹配患者,在术后经动态心电图监测96 h,分析房颤发生率以及术后不同时间段的心率变异性指标变化。结果 胸腔镜组术后发生房颤19例（发生率17.0%）、开胸组发生20例（17.9%）,房颤发生时间均在术后24 h之后,两组之间无显著差异。两组术后整体心率变异性无显著差异。结论 胸腔镜手术并不能降低房颤的发生率,不同方式肺叶切除术对术后心率变异性无显著影响。     

心率变异性分析的检测指标及方法

心率变异性（ＨＲＶ）分析是近年来日益兴起的无创伤性检测自主神经张力的方法。而自主神经张力改变同各种心血管疾病的发生、发展及预后关系密切。因此ＨＲＶ分析在评价心血管疾病预后及猝死发生方面有重要价值。本文旨在介绍ＨＲＶ分析有关检测指标及方法，以使读者对ＨＲＶ充分了解。     

依那普利对心肌梗死后自主神经功能时间生物学特征的影响

目的探讨心肌梗死后自主神经功能（ANS）时间生物学特征的改变及药物影响。方法将69例陈旧性心肌梗死患者随机分为两组，组Ⅰ根据病情应用硝酸盐类、β-受体阻滞剂（仅限倍他乐：克）和利尿剂（仅限双氨克尿塞）治疗，组Ⅱ在此治疗方案基础上加用依那普利，人选30例健康人为对照组。应用动态心电监测仪及其心率变异性（HRV）分析软件进行24h心电监测，应用余弦拟和法统计分析软件进行统计学处理。结果三组的HRV昼夜分布均呈近日节律分布。组Ⅰ、组ⅡANs功能明显受损，交感神经与迷走神经兴奋性活动的基本节律发生改变。经治疗后组Ⅱ的ANS功能有了明显恢复。绪论依那普利治疗对ANS功能的恢复可能有较好作用。     

冠心病心肌缺血发作时自主神经功能的变化

采用心率变异性（ＨＲＶ）自回归（ＡＲ）和快速傅立叶转换（ＦＦＴ）两种频域法对比分析５０例冠心病病人和５０例正常人ＨＲＶ的昼夜变化及心肌缺血时与无缺血时的ＨＲＶ变化，并对两种频域法进行相关性分析。结果表明：冠心病组和对照组的ＨＲＶ呈昼夜变化，白天以低频成分（ＬＦ，代表交感神经活性）占优势，夜间以高频成分（ＨＦ，反映迷走神经活性）占优势；冠心病心肌缺血病人的ＨＲＶ昼夜变化减少（ＡＲ法，ＬＦ／ＨＦ：冠心病组为２．２±０．９ＶＳ０．８±１．１，对照组为２．４±１．２ＶＳ０．３±０．８，Ｐ＜０．０５），清晨自主神经调节发生突然变化，即由迷走神经兴奋转为交感神经兴奋；劳累型心绞痛病人心肌缺血时ＬＦ增高（１６３±１３２ｍｓ２ＶＳ２４７±１６２ｍｓ２，Ｐ＜０．０５），ＨＦ减少（７５±２１ｍｓ２ＶＳ５７±１１ｍｓ２，Ｐ＜０．０５），心肌缺血次数与ＬＦ呈正相关（ｒ＝０．６７）．上午６～１０时心肌缺血发生最多。两种能谱估计法呈高度正相关（ｒ＝０．９８）。提示：劳累型心绞痛的发作与交感神经功能亢进、迷走神经张力减弱有关；清晨自主神经功能调节的突然变化可起板机作用，使此时心肌缺血的发生频度增高。     

心脏自主神经活动在阵发性心房颤动发生和维持中的作用

心脏自主神经尤其是心迷走神经的功能活动与阵发性心房颤动（房颤）的发生和维持关系密切。据一些临床实验观察表明阵发性房颤与副交感神经的紧张性升高有关。Bettoni等对连续非选择的77例阵发性房颤患者的动态心电图检查结果进行分析发现：阵发性房颤的发作与自主神经紧张性的变化直接相关，首先是肾上腺素能神经紧张性升高，但很快转为以迷走神经紧张性升高为主；并且心率离散度的变化在有器质性与无器质性心脏病患者中差异无统计学意义。本文就阵发性房颤的发生和维持与心脏自主神经功能活动的关系作一综述。     

心房重构在房颤中的作用

房颤的发病机制非常复杂,与心房的重构(包括电学重构、解剖重构和自主神经系统重构)密切相关.房颤可诱导离子通道蛋白表达和(或)功能异常,进而反馈性地促进心房功能性折返基质的形成,发生电学重构;循环往复的电学重构造成心房基质的改变,失活的心房肌细胞被纤维组织替代,心房逐渐纤维化,出现解剖重构;与此同时,心房广泛的纤维化进一步阻碍电冲动的传导,反过来加重电学重构;自主神经系统重构可通过正向反馈环机制促进房颤的维持和复发.早期治疗心房重构可延迟甚至预防房颤的发生和发展.     

自主神经在血管迷走性晕厥发病中的作用

目的探索自主神经系统如何介导血管迷走性晕厥的发生。方法对９４例不明原因晕厥的病人进行了倾斜试验。倾斜过程中动态监测心电图、血压和心率。进行心率变异性分析。结果４４例发生晕厥，其中基础倾斜试验晕厥３２例，阳性率３４．０％；异丙肾上腺素晕厥１２例，阳性率增加１２．８％。晕厥时ＬＦ及ＨＦ明显下降，ＶＬＦ明显升高。结论（１）血管迷走性晕厥时，交感神经和迷走神经张力受抑制，导致血管扩张，血压下降。（２）ＶＬＦ的升高与ＬＦ的下降明显相关。ＶＬＦ升高的意义有待深入研究     

Role of autonomic tone in the initiation and termination of paroxysmal atrial fibrillation in patients without structural heart disease

INTRODUCTION: Previous studies have suggested that paroxysmal atrial fibrillation (PAF) of vagal origin often occurs at night and PAF of sympathetic origin occurs during the daytime; however, autonomic tone after spontaneous termination of PAF has not been determined. The aim of this study was to evaluate by heart rate variability (HRV) analysis the relationship between the time of PAF onset and autonomic tone before and after PAF. METHODS AND RESULTS: Twenty-three patients (65 +/- 2 years) who underwent 24-hour ambulatory monitoring, had one or more episodes of PAF (>30 min), and had maintained normal sinus rhythm for >60 min before/after PAF were enrolled in this study. Mean duration of PAF was 6.2 +/- 1.2 hours. HRV parameters were analyzed in a 10-minutes section at 60 minutes, 20 minutes, and immediately before the onset of PAF and after its termination. PAF began at night in 14 patients (group N) and during the daytime in 9 patients (group D). In group N, the high-frequency (HF) component and low-frequency (LF) component showed a significant decrease after PAF; PAF was preceded by a gradual increase in HF and LF. Changes in the LF/HF ratio, however, did not occur before or after PAF. Conversely, group D showed a significant increase in the LF/HF ratio before PAF and a decrease in LF and the LF/HF ratio after PAF, but no changes in HF. These changes in HRV parameters were not influenced by the duration or termination time of PAF. CONCLUSION: This study suggests that the autonomic nervous system plays an important role in both the initiation and termination of PAF. Furthermore, the time of PAF onset influences the autonomic tone at the initiation and termination of PAF.     

Initiating mechanisms of paroxysmal atrial fibrillation.

BACKGROUND: The understanding of the onset mechanisms of paroxysmal atrial fibrillation (AF) may help to develop preventive therapy. Specific heart rate (HR) patterns and autonomic changes immediately before the onset of paroxysmal AF are not fully investigated. We undertook the present study to assess HR and heart rate variability (HRV) changes before the onset of AF using 24-h Holter electrocardiographic analysis in patients without antiarrhythmic medication. METHODS AND RESULTS: In 27 patients, 48 episodes of AF, lasting more than 30s and preceded by sinus rhythm for more than 1h were analysed. The hour preceding AF was divided in 5- and 30 min blocks. HR was also analysed in the last 15 beats. In 21% of the episodes, HR decreased >or=5% in the last 5 min (defined as deceleration); it increased >or=5% in 37% (defined as acceleration). HR, standard deviation (SD) and SD corrected for RR interval changed significantly in the last 5 min in the total group. Acceleration and deceleration were already visible over 30-min blocks in both these subgroups; changes in SD were only seen in the accelerators. The number of atrial premature beats (PACs) increased before AF, most clearly in the accelerators. Spectral HRV analysis revealed no additional information. CONCLUSIONS: Changes in HR, SD, and an increased number of PACs herald AF from at least 30 min before onset, more pronounced in accelerators. Spectral HRV parameters are not useful to foresee AF onset. This has possible implications for device therapy.     

Interaction between the autonomic nervous system and atrial tachyarrhythmias

Atrial tachyarrhythmias are the most common arrhythmias in the general population. The abundant experimental evidence suggests that the autonomic nervous system plays an important role in the occurrence of atrial arrhythmias. However, complex interactions of the autonomic nervous system with the arrhythmogenic substrate make it difficult to correlate human arrhythmias with the laboratory data. Development of new methods to explore the subtle modulation of the autonomic nervous system may have implications for understanding the arrhythmogenic mechanism and providing an effective therapy.     

Inducibility of atrial fibrillation during atrioventricular pacing with varying intervals: role of atrial electrophysiology and the autonomic nervous system

INTRODUCTION: Patients receiving VVI pacemakers have a higher incidence of paroxysmal atrial fibrillation (AF) than those receiving DDD pacemakers. However, the mechanism behind the difference is not clear. The purpose of this study was to investigate whether atrial electrophysiology and the autonomic nervous system play a role in the occurrence of AF during AV pacing. METHODS AND RESULTS: The study population consisted of 28 patients who had (group I, n = 15) or did not have (group II, n = 13) AF induced by a single extrastimulus during pacing with different AV intervals. Atrial pressure, atrial size, atrial effective refractory periods, and atrial dispersion were evaluated during pacing with different AV intervals. Twenty-four-hour heart rate variability and baroreflex sensitivity also were examined. Atrial pressure, atrial size, effective refractory periods in the right posterolateral atrium and distal coronary sinus, and atrial dispersion increased as the AV interval shortened from 160 to 0 msec. During AV pacing, group I patients had greater minimal (52+/-17 vs 25+/-7 msec; P < 0.005) and maximal (76+/-16 vs 36+/-9 msec; P < 0.005) atrial dispersion than group II patients. The differences in atrial size and atrial dispersion among different AV intervals were greater in patients with AF than in those without AF. Baroreflex sensitivity (6.6+/-1.7 vs 3.9+/-1.0; P < 0.00005), but not heart rate variability, was higher in patients with AF than in those without AF. CONCLUSION: Abnormal atrial electrophysiology and higher vagal reflex activity can play important roles in the genesis of AF in patients receiving pacemakers.     

The cardiac autonomic nervous system: A target for modulation of atrial fibrillation

The cardiac autonomic nerve system (CANS) is a potentially potent modulator of the initiation and perpetuation of atrial fibrillation (AF). In this review, we focus on the relationship between the autonomic nervous system (ANS) and the pathophysiology of AF and the potential benefit and limitations of neuromodulation in the management of this arrhythmia from eight aspects. We conclude that Activation and Remodeling of CANS involved in the initiation and maintenance of AF. The network control mechanism, innervation regions, and sympathetic/parasympathetic balance play an important role in AF substrate. And the formation of Complex Fractional Atrial Electrograms also related to CANS activity. In addition, modulating CANS function by potential therapeutic applications include ganglionated plexus ablation, renal sympathetic denervation, and low‐level vagal nerve stimulation, may enable AF to be controlled. Although the role of the ANS has long been recognized, a better understanding of the complex interrelationships of the various components of the CANS will lead to improvement of treatments for this common arrhythmia.     

Preoperative alterations in correlation properties and complexity of R-R interval dynamics predict the risk of atrial fibrillation after coronary artery bypass grafting in patients with preserved left ventricular function

Introduction: We evaluated whether there are constant preoperative alterations in nonlinear R–R interval dynamics that associate with the risk of postoperative atrial fibrillation in patients with preserved left ventricular function. Methods: We analyzed mean normal‐to‐normal R–R intervals, short‐term scaling exponent of detrended fluctuation analysis (DFA α₁), approximate entropy and entropy of symbolic dynamics (SymDyn En) from 10‐minute ECG recordings during rest, paced breathing, and passive tilt performed 1 day before surgery in 67 elective coronary artery bypass grafting patients. Results: Nineteen patients developed postoperative atrial fibrillation. The preoperative DFA α₁ was constantly lower in patients developing postoperative atrial fibrillation than in patients remaining in sinus rhythm (P = 0.016); during spontaneous breathing, the DFA α₁ was 0.93 ± 0.33 in patients with atrial fibrillation and 1.13 ± 0.24 in patients with sinus rhythm. The entropy of symbolic dynamics was higher during the spontaneous breathing in patients with atrial fibrillation than in patients with sinus rhythm (4.72 ± 0.51 vs 4.36 ± 0.51, P = 0.012). Higher short‐term scaling exponent of detrended fluctuation analysis during the spontaneous breathing period reduced the risk of postoperative atrial fibrillation (OR 0.31 for an interquartile increase in DFA α₁, 95% CI 0.13–0.78), while higher entropy of symbolic dynamics increased it (OR 3.16 for an interquartile increase in SymDyn En, 95% CI 1.23–8.10), independently of age and clinical risk factors. Conclusion: The preoperatively altered nonlinear R–R interval dynamics were independent predictors of postoperative atrial fibrillation and might become a useful tool for the risk assessment of atrial fibrillation.     

Low-level vagosympathetic nerve stimulation inhibits atrial fibrillation inducibility: direct evidence by neural recordings from intrinsic cardiac ganglia

Intrinsic Cardiac Ganglia Activity Inhibited by Low‐Level Vagal Stimulation . Introduction: We hypothesized that low‐level vagosympathetic stimulation (LL‐VNS) can suppress atrial fibrillation (AF) by inhibiting the activity of the intrinsic cardiac autonomic nervous system (ICANS). Methods and Results: Wire electrodes inserted into both vagosympathetic trunks allowed LL‐VNS at 10% or 50% below the voltage required to slow the sinus rate or atrioventricular conduction. Multielectrode catheters were attached to atria, atrial appendages and all pulmonary veins. Electrical stimulation at the anterior right and superior left ganglionated plexi (ARGP, SLGP) was used to simulate a hyperactive state of the ICANS. Effective refractory period (ERP) and window of vulnerability (WOV) for AF were determined at baseline and during ARGP+SLGP stimulation in the presence or absence of LL‐VNS. Neural activity was recorded from the ARGP or SLGP. ARGP+SLGP stimulation induced shortening of ERP, increase of ERP dispersion and increase of AF inducibility (WOV), all of which were suppressed by LL‐VNS (10% or 50% below threshold) at all tested sites. Sham LL‐VNS failed to induce these changes. The effects of LL‐VNS were mediated by inhibition of the ICANS, as evidenced by (1) LL‐VNS suppression of the ability of the ARGP stimulation to slow the sinus rate, (2) the frequency and amplitude of the neural activity recorded from the ARGP or SLGP was markedly suppressed by LL‐VNS, and (3) the spatial gradient of the ERP and WOV from the PV‐atrial junction toward the atrial appendage was eliminated by LL‐VNS. Conclusions: LL‐VNS suppressed AF inducibility by inhibiting the neural activity of major GP within the ICANS. (J Cardiovasc Electrophysiol, Vol. 22, pp. 455‐463)     

Predictive value of heart rate variability for the recurrence of chronic atrial fibrillation after electrical cardioversion

BACKGROUND: The relation between heart rate variability (HRV) and occurrence of atrial fibrillation (AF) in paroxysmal AF has been well studied, but there are controversial observations regarding the relation of HRV parameters to the recurrence of chronic AF after cardioversion. HYPOTHESIS: The present study compared HRV parameters of patients with chronic AF on the second day of cardioversion with a healthy control group and investigated their predictive value for AF recurrence. METHODS: Forty-one patients with chronic AF (> 3 months), who had various underlying cardiovascular disorders, were enrolled to the study. Of these, 31 patients were successfully cardioverted by external direct current shock, but 27 patients fulfilled the entry criteria. Twenty healthy subjects served as a control group. On the second day of restoration of sinus rhythm, 24-h Holter recording was obtained and the following time-domain indices of HRV were measured: SDNN (the standard deviation of the mean RR interval expressed in ms), SDANN (the SD of the averages of RR intervals in all 5-min segments of the 24-h recording), rMSSD (the root mean square of differences of successive RR intervals), and pNN50 (the percentage of adjacent RR intervals that differed by more than 50 ms). Patients were followed-up for 6 weeks for recurrence of AF. RESULTS: After cardioversion, SDNN and SDANN were found to be significantly lower in the AF group than in the control group (86.4 +/- 31.7 ms vs. 142.1 +/- 40.2 ms, and 57 +/- 17.4 ms vs. 124.4 +/- 37.7 ms, p < 0.001 and p < 0.001, respectively). The indices of vagal modulation of heart rate (rMSS and pNN50) were not different between the AF group and the control group. Recurrence of AF was observed in 15 patients. In these patients, all HRV parameters were significantly depressed compared with those with maintained sinus rhythm. Logistic regression analysis revealed that only decreased pNN50 was an independent predictor of AF relapse (relative risk = 1.5, p = 0.02, 95% confidence interval 1.1-2.2). There was also a trend toward a shortened SDNN as a predictor of AF recurrences. CONCLUSION: Suppressed HRV parameters and decreased vagal tone are probably a risk factor for AF recurrences after cardioversion to sinus rhythm in a specific subset of patients with chronic AF.