老年人动态心电图心律失常特点及对阵发性 房颤的诊断

目的:分析65岁以上老年人十二导联动态心电图(12-Holter)心律失常的特点及其对阵发性房颤的诊断价值。方法:①采用回顾性分析的方法,随机选择500例65岁以上老年人的动态心电图进行心律失常情况的统计分析,并同时选择500例小于65岁的心电图作为对照;②另选择500例65岁以上老年人的十二导联普通心电图(ECG)作为对照,对比分析12-Holter与ECG两种方法对老年人阵发性房颤的检出率。结果:①65岁以上老年人动态心电图各种心律失常、ST-T改变的发生率高。而在各类心律失常中房性早搏、室性期前收缩、房性心动过速、房颤发生率较高。②动态心电图对于阵发性房颤的检出率显著高于普通十二导联心电图。结论:①老年人动态心电图检查结果异常率高;②与普通心电图比较,动态心电图诊断老年人阵发性房颤有较高的价值。     

Predicting initiation and termination of atrial fibrillation from the ECG.

Atrial fibrillation is the most common cardiac arrhythmia, affecting more than two million people in the US. Several therapies for patients with atrial fibrillation are available, but methods to help physicians select the optimal therapy for an individual patient are still required. Knowledge of whether a patient with a normal ECG will exhibit atrial fibrillation in the future, as well as whether atrial fibrillation will terminate spontaneously, would be very useful in clinical routine. The paper presents a software system for predicting the initiation and termination of atrial fibrillation from the ECG. The algorithms have been validated on ECGs from several signal databases. Prediction of the initiation of atrial fibrillation was achieved by detecting premature heart beats and analyzing the morphology of their P waves. Prediction of the termination of atrial fibrillation was based on calculation of the major atrial frequency. This frequency has been shown to decrease significantly prior to the termination of atrial fibrillation. Nevertheless, the effect is much less distinct in the large data set used for this study compared to previous studies. The initiation of atrial fibrillation, however, could be correctly predicted in approximately 75% of the data analyzed.     

Atrial fibrillation and pacing algorithms

Pacing prevention algorithms have been introduced in order to maximize the benefits of atrial pacing in atrial fibrillation prevention. It has been demonstrated that algorithms actually keep overdrive atrial pacing, reduce atrial premature contractions, and prevent short-long atrial cycle phenomenon, with good patient tolerance. However, clinical studies showed inconsistent benefits on clinical endpoints such as atrial fibrillation burden. Factors which may be responsible for neutral results include an already high atrial pacing percentage in conventional DDDR, non-optimal atrial pacing site and deleterious effects of high percentages of apical ventricular pacing. Atrial antitachycardia pacing (ATP) therapies are effective in treating spontaneous atrial tachyarrhythmias, mainly when delivered early after arrhythmia onset and/or on slower tachycardias. Effective ATP therapies may reduce atrial fibrillation burden, but conflicting evidence does exist as regards this issue, probably because current clinical studies may be underpowered to detect such an efficacy. Wide application of atrial ATP may reduce the need for hospitalizations and electrical cardioversions and favorably impact on quality of life. Consistent monitoring of atrial and ventricular rhythm as well as that of ATP effectiveness may be extremely useful for optimizing device programming and pharmacological therapy.     

Non-pharmacological treatment of atrial fibrillation

In selected patients with atrial fibrillation and severe symptoms, non-pharmacological treatment may be an alternative or supplement to drug therapy. Atrioventricular nodal radiofrequency ablation (requires pacemaker implantation), or atrial pacing for sick sinus syndrome, are established treatment modalities. All other non-pharmacological therapies for atrial fibrillation are still experimental. After the Maze operation, atrial depolarization has to follow one specific path determined by surgical scars in the myocardium. This prevents new episodes of atrial fibrillation, but at a cost of perioperative morbidity and mortality. Catheter-based "Maze-like" radiofrequency ablation is technically difficult, and thrombo-embolic complications may occur. Paroxysmal atrial fibrillation sometimes is initiated by spontaneous depolarizations in a pulmonary vein inlet. Radio frequency ablation against such focal activity has been reported with high therapeutic success, but the results await confirmation from several centres. For ventricular rate control, most electrophysiologists presently prefer ablation to induce a complete atrioventricular conduction block (with pacemaker) rather than trying to modify conduction by incomplete block. Atrial or dual chamber pacing may prevent atrial fibrillation induced by bradycardia. It remains to confirm that biatrial or multisite right atrial pacing prevents atrial fibrillation more efficiently than ordinary right atrial pacing. An atrial defibrillator is able to diagnose and convert atrial fibrillation. The equipment is expensive, and therapy without sedation may be unpleasant beyond tolerability.     

Apocynin: a potent NADPH oxidase inhibitor for the management of atrial fibrillation

Abstract

Oxidative stress in atrial tissue may be causally related to atrial fibrillation as suggested by clinical and animal studies. Reactive oxygen species (ROS) are known to play a key role in fibrosis and the induction of after-depolarization and triggered activity. Therefore, suppressing oxidative stress may have a potential beneficial role in the management of atrial fibrillation. Since increased NADPH oxidase activity is shown to play a key role in generation of ROS in atrial tissue and in atrial fibrillation, our proposed strategy to target upstream inhibition of ROS production by inhibition of NADPH oxidase activity may provide a novel approach to prevent atrial fibrillation recurrences. We hypothesize that apocynin could be effective against atrial fibrillation, by virtue of its potent inhibitory effect of a major oxidative system (i.e. NADPH oxidase) combined with its demonstrated anti-inflammatory, antifibrotic and antihypertensive effects which partially are driven from its antioxidant property. Atrial fibrillation is known to be initiated by the interaction of these multiple factors.     

Cryoablation in persistent atrial fibrillation – a critical appraisal

Ablation of atrial fibrillation is an established treatment for the management of patients with paroxysmal and persistent atrial fibrillation. The complex pathophysiology of persistent atrial fibrillation has fuelled the concept of adjunctive substrate modification on top of pulmonary vein isolation. However, recent studies have failed to demonstrate additive benefit from complex ablation approaches, thus supporting that standalone pulmonary vein isolation may prove sufficient, at least as the initial ablation strategy in persistent atrial fibrillation. In this premise, the new-generation cryoballoon is an attractive option in this demanding subgroup of patients due to its reliable efficacy in achieving pulmonary vein isolation combined with collateral debulking of the neighbouring atrial myocardium. In this review, we present a critical appraisal of the role of cryoablation in patients with persistent atrial fibrillation, discussing related technical considerations and existing scientific evidence.     

Characterization of fibrillatory rhythms by ensemble vector directional analysis

Recent studies have demonstrated that fibrillatory rhythms are not random phenomena but have definable patterns. However, standard mapping techniques may have limitations in their ability to identify the organization of fibrillation. The purpose of this study was to develop and apply a method, "ensemble vector mapping," for characterizing the spatiotemporal organization of fibrillation. Ventricular fibrillation was induced by burst pacing in normal mongrel dogs. In a separate protocol, atrial fibrillation was induced by epicardial aconitine application. Epicardial electrograms were recorded from a 112-electrode plaque array using a computerized mapping system. Vectors were created by summing orthogonal bipolar electrograms. The magnitude of the vectors was transformed using a logarithmic function, integrated over time, and normalized for local electrogram amplitude to produce an "ensemble vector" index whose magnitude is high when beat-to-beat activation direction is consistent and low when activation direction is variable. The mean index was 137 +/- 36 mV/s during ventricular pacing at a cycle length of 300 ms but only 39 +/- 23 mV/s during ventricular fibrillation (P < 0.001). The ensemble vector index was also lower during atrial fibrillation (60 +/- 54 mV/s) than during atrial pacing (115 +/- 27 mV/s, P < 0.01 vs. atrial fibrillation) but not as low as during ventricular fibrillation (P < 0.05, atrial vs. ventricular fibrillation). The index was also capable of distinguishing atrial tachycardia from atrial fibrillation. Ensemble vector mapping produces an objective assessment of the consistency of myocardial activation during fibrillation. The consistency of activation direction differs in different models of fibrillation and is higher during atrial than ventricular fibrillation. This technique has the potential to rapidly characterize repetitive activation patterns in fibrillatory rhythms and may help distinguish among different characteristics of fibrillatory rhythms.     

46例甲状腺功能亢进性心脏病临床分析

目的：探讨甲状腺功能亢进性心脏病的防治措施。方法：回顾性分析2003年6月至2009年6月收治的46例甲状腺功能抗进性心脏病患者的临床资料。其中男20例,女26例,年龄15-78岁,病程7月-30年;伴心功能衰竭28例（60.9%）,心房纤颤30例（65.2%）,和病态窦房结综合征1例（2.2%）。结果：46例患者均服用甲状腺药物治疗后,甲亢病情缓解,心力衰竭好转。30例心房纤颤患者中,19例恢复窦性心律,剩余11例平均心室率控制在70-100次/min。结论：甲亢性心脏病治疗的关键在于早期诊断,甲亢病情控制后,绝大部分心脏异常可减轻或消失。     

Effect of atrio-ventricular conduction on the appearance of supraventricular arrhythmia and thrombotic complications in patients with chronic stimulation of cardiac ventricles in sick sinus syndrome]

Two hundred three patients with sick sinus node disease were treated with continuous ventricular stimulation between 1981 and 1985. To 1988, 168 patients aged between 26 and 88 years were followed-up for 5.1 years on the average. All these patients were divided into two groups: I (93 patients) with sinusal bradycardia, and group II (93 patients) with brady-tachycardia. Ventriculo-atrial conduction was seen in 82.61% of patients of group I in whom the implantation of electric stimulator produced the attacks of atrial fibrillation, and in 44.23% of patients without such attacks (p < 0.01); in 80.77% of patients of group II in whom atrial fibrillation became stable with time, and in 50.57% with intermittent atrial fibrillation (p < 0.01) ventriculo-atrial conduction was noted. It may be concluded, that the presence of ventriculo-atrial conduction in patients with prolonged stimulation of the cardiac ventricles favor the occurrence and stabilization of the paroxysmal atrial fibrillation and thrombotic complications.     

Recent Trends in Imaging for Atrial Fibrillation Ablation

Catheter ablation provides an important treatment option for patients with both paroxysmal and persistent atrial fibrillation. It mainly involves pulmonary vein isolation and additional ablations in the left atrium in persistent cases. There have been significant advancements in this procedure to enhance the safety and effectiveness. One of them is the evolution of various imaging modalities to facilitate better visualization of the complex left atrial anatomy and the pulmonary veins in order to deliver the lesions accurately. In this article, we review the electroanatomic mapping systems including the magnetic-based and impedence-based systems. Each of these mapping systems has its own advantages and disadvantages. In addition, we also discuss the role of intracardiac echocardiography and three dimensional rotational angiography in atrial fibrillation ablation.     

脂肪因子瘦素和内脂素与心房颤动关系的研究

摘要 目的：心房颤动（Atrial fibrillation,AF）是最常见的心律失常之一,其发生机制目前尚未完全阐明。多项研究表明脂肪因子（Adipokines）中的瘦素（leptin）、内脂素（Visfatin）与心血管疾病的关系密切,本研究拟探讨瘦素、内脂素与心房颤动的关系。方法：本研究通过收集检测AF组、窦性心律组外周血及心外膜脂肪组织,检测瘦素、内脂素分泌水平来探讨瘦素、内脂素与AF发生的相关性。结果：房颤组血清内脂素的平均浓度为15.95±10.44 ng/mL,窦性心律组为20.28±12.90 ng/mL（P=0.169）;房颤组血清瘦素的平均浓度为1.48 ng/mL,窦律组为2.56 ng/mL（P=0.0027）,窦性心律组血清瘦素水平明显高于心房颤动组;心外膜脂肪组织中,瘦素在房颤组中的表达量显著低于窦性心律组（P=0.032）,内脂素在两组中的表达无显著统计学差异（P=0.06）。结论：临床患者外周血血清及心外膜脂肪组织中高水平的瘦素可能降低房颤的发生率,然而,内脂素与房颤可能不具有相关性。     

基于滤除R波的主导频率算法的房颤心内信号分析

为了进一步探究房颤患者心内不同位置信号的主导频率(Dominant frequency,简称DF)的关联性,本文对传统的Botteron’s算法进行了改进。当信号中含有较大幅值的室波时,该改进算法可以更好地提取DF。利用该算法对20例临床房颤消融手术的冠状静脉窦(Coronary sinus,简称CS)导管、环肺静脉(Pulmonary veins,简称PV)导管采集的信号进行了观察和分析。在大部分病例中都能观察到其CS和PV的信号里都存在相同频率的DF;同时发现CS的DF并不仅仅来自当前标测的PV。实验结果表明:房颤的潜在病灶区域不仅仅具有较高频率的DF,且其DF的频率应当与心房采集的DF频率存在对应关系。这或许可以为寻找房颤的潜在病灶区域提供参考。     

经食道超声心动图评估特发性房颤左心房左心耳的价值

目的:研究经食道超声心动图(TEE)评估特发性房颤左心房左心耳的临床价值。方法:选择自2015年1月到2016年8月在医院接受诊治的特发性房颤患者100例纳入本次研究,阵发性房颤92例,记为阵发性房颤组;持续性房颤8例,记为持续性房颤组。另选同期在医院进行健康体检的心功能正常志愿者90例作为对照组。利用TEE对受试者进行检查,对比房颤组与对照组的左心房及左心耳参数,是否含有自发性显影(LASEC)的房颤患者的左心房及左心耳参数,利用TEE分析对房颤患者的预后情况。结果:阵发性房颤组左心房的前后径和左右径,左心耳血流最大的排空速度(Lev)均明显小于对照组,左心耳的面积变化率及最大的充盈速度(Lfv)均明显大于对照组,差异有统计学意义(P0.05)。持续性房颤组左心房的前后径和左右径均明显大于对照组,左心耳的面积变化率、Lev及Lfv均明显小于对照组,差异有统计学意义(P0.05)。阵发性房颤组左心房的前后径和左右径均明显小于持续性房颤组,左心耳的面积变化率、Lev及Lfv均明显大于持续性房颤组,差异有统计学意义(P0.05)。有LASEC者左心房的前后径和左右径均明显大于无LASEC者,左心耳的面积变化率、Lev及Lfv均明显小于无LASEC者,差异有统计学意义(P0.05)。100例房颤患者中发现34例LASEC,占34.00%,其中有18例患者合并有左心耳血栓,占18.00%。总计有66例患者接受导管射频消融疗法,占66.00%,均未在术中及术后7d内出现血栓及栓塞并发症。结论:利用TEE对特发性房颤的患者左心房及左心耳进行评估,有利于更好的辅助患者的临床治疗,值得重视。     

Congenital Short QT Syndrome

The Short QT Syndrome is a recently described new genetic disorder, characterized by abnormally short QT interval, paroxysmal atrial fibrillation and life threatening ventricular arrhythmias. This autosomal dominant syndrome can afflict infants, children, or young adults; often a remarkable family background of cardiac sudden death is elucidated. At electrophysiological study, short atrial and ventricular refractory periods are found, with atrial fibrillation and polymorphic ventricular tachycardia easily induced by programmed electrical stimulation. Gain of function mutations in three genes encoding K⁺ channels have been identified, explaining the abbreviated repolarization seen in this condition: KCNH2 for I_kr (SQT1), KCNQ1 for I_ks (SQT2) and KCNJ2 for I_k1 (SQT3). The currently suggested therapeutic strategy is an ICD implantation, although many concerns exist for asymptomatic patients, especially in pediatric age. Pharmacological treatment is still under evaluation; quinidine has shown to prolong QT and reduce the inducibility of ventricular arrhythmias, but awaits additional confirmatory clinical data.     

Rate-control or rhythm-control: where do we stand?

Atrial fibrillation is the most common sustained rhythm disturbance and its prevalence is increasing worldwide due to the progressive aging of the population. Current guidelines clearly depict the gold standard management of acute symptomatic atrial fibrillation but the best-long term approach for first or recurrent atrial fibrillation is still debated with regard to quality of life, risk of new hospitalizations, and possible disabling complications, such as thromboembolic stroke, major bleeds and death. Some authors propose that regaining sinus rhythm in all cases, thus re-establishing a physiologic cardiac function not requiring a prolonged antithrombotic therapy, avoids the threat of intracranial or extracranial haemorrhages due to Vitamin K antagonists or aspirin. On the contrary, advocates of a rate control approach with an accurate antithrombotic prophylaxis propose that such a strategy may avoid the risk of cardiovascular and non cardiovascular side effects related to antiarrhythmic drugs. This review aims to explore the state of our knowledge in order to summarize evidences and issues that need to be furthermore clarified.     

Role of atrial fibrillation threshold evaluation on guiding treatment

Atrial fibrillation could be induced reproducibly by 50 Hz rapid stimulation which was given through systolic and early diastolic phase of atrial excitation. Duration of atrial fibrillation induced in this way was roughly dependent on the current amplitude of the stimulation. The minimum current that could induce long-lasting atrial fibrillation (30 sec in the clinical setting, 2 sec in the rabbit or rat model) was defined as atrial fibrillation threshold (AFT). AFT was larger in patients who had history of atrial fibrillation than those who did not. Anti-arrhythmic drugs raised AFT by various degrees both in experimental and clinical cases. Long-term efficacy of a drug could be predicted in a patient, measuring how much the drug increased AFT (cut-off point = 5 mA increase). AFT is a useful marker to evaluate atrial vulnerability and to guide pharmacological treatment of atrial fibrillation.     

Kidney function after renal arterial embolism

Seven patients with atrial fibrillation had acute unilateral renal pain associated with suppression of function in the affected kidney. This was ascribed to renal embolism. Arteriography performed in four patients showed abnormalities in the renal arterial tree in three, though thrombus in a main artery was present in only one.Considerable function returned spontaneously to the affected kidney in six patients as judged by intravenous pyelography or renography. In two patients the sole functioning kidney was affected, leading to acute oliguric renal failure, but renal function recovered in each case. The routine use of anticoagulants in persistent atrial fibrillation is justified by such cases.     

Isolation of persistent left superior vena cava during atrial fibrillation ablation

Persistent left superior vena cava is a rarely seen anomaly but it may be an arrhythmogenic source for paroxysmal atrial fibrillation. Furthermore, the complex anatomicregion between the left superior vena cava and the pulmonary veins may leads to misinterpretation of the pulmonary vein recordings during atrial fibrillation ablation. Approaches that might be helpful to overcome these problems are discussed in this case report.     

Identification of patients with atrial fibrillation using HRV parameters]

Atrial fibrillation is the most common sustained cardiac rhythm disturbance. One of the most drastic complications is embolism, particularly stroke. Patients with atrial fibrillation have to be identified. This can lead to early therapy and thus avoiding strokes. The algorithm presented here detects atrial fibrillation securely and reliably. It is based on a single-channel ECG, which takes 60 min. First, the R-peaks are detected from the ECG and the RR interval is calculated. To be independent from pulse variations, the RR interval is normalized to 60 bpm. A parameter of heart rate variability is calculated in time domain (SDSD) and the so-called Poincaré plot is generated. The image analysis of the figures of the Poincaré plot is made automatically. The results from analysis in time domain, as well as image analysis, yield a risk level, which indicates the probability for the occurrence of atrial fibrillation. Even if there is no atrial fibrillation in the ECG while analyzing, it is possible to identify patients with atrial fibrillation. The sensitivity depends on the burden of atrial fibrillation. Even if a burden of 0% is assumed, the results still prove satisfactory (sensitivity of nearly 83%).     

Dynamic Approximate Entropy Electroanatomic Maps Detect Rotors in a Simulated Atrial Fibrillation Model

There is evidence that rotors could be drivers that maintain atrial fibrillation. Complex fractionated atrial electrograms have been located in rotor tip areas. However, the concept of electrogram fractionation, defined using time intervals, is still controversial as a tool for locating target sites for ablation. We hypothesize that the fractionation phenomenon is better described using non-linear dynamic measures, such as approximate entropy, and that this tool could be used for locating the rotor tip. The aim of this work has been to determine the relationship between approximate entropy and fractionated electrograms, and to develop a new tool for rotor mapping based on fractionation levels. Two episodes of chronic atrial fibrillation were simulated in a 3D human atrial model, in which rotors were observed. Dynamic approximate entropy maps were calculated using unipolar electrogram signals generated over the whole surface of the 3D atrial model. In addition, we optimized the approximate entropy calculation using two real multi-center databases of fractionated electrogram signals, labeled in 4 levels of fractionation. We found that the values of approximate entropy and the levels of fractionation are positively correlated. This allows the dynamic approximate entropy maps to localize the tips from stable and meandering rotors. Furthermore, we assessed the optimized approximate entropy using bipolar electrograms generated over a vicinity enclosing a rotor, achieving rotor detection. Our results suggest that high approximate entropy values are able to detect a high level of fractionation and to locate rotor tips in simulated atrial fibrillation episodes. We suggest that dynamic approximate entropy maps could become a tool for atrial fibrillation rotor mapping.