Dual independent atrial tachycardias after ablation of chronic atrial fibrillation

We report the case of a 71-year-old man with two atrial tachycardias evolving simultaneously and independently in two dissociated regions after extensive ablation for chronic atrial fibrillation. One tachycardia was a focal tachycardia originating from the right inferior pulmonary vein and activating the posterior left atrium with a 2:1 conduction block, while the other tachycardia was an atrial flutter circulating around the tricuspid annulus, activating the right atrium and the anterior wall of the left atrium. These two atrial tachycardias were successfully ablated prior to restoration of sinus rhythm.     

Electrocardiographic differentiation of atrial flutter from atrial fibrillation by physicians

The purpose of this study was to determine the ability of physicians to differentiate atrial flutter from atrial fibrillation on a surface electrocardiogram (ECG). A questionnaire containing three 12-lead ECGs was mailed to 689 physicians, with multiple-choice questions asking whether the rhythm on each ECG was atrial flutter or atrial fibrillation. ECG 1 showed atrial fibrillation with prominent atrial activity (>0.2 mV) in lead V1; ECG 2 displayed atrial fibrillation with prominent atrial activity (>0.2 mV) in leads III and V1; and ECG 3 displayed atrial flutter. Overall, ECG1 was correctly identified as atrial fibrillation by 79% of physicians, ECG 2 was correctly identified as atrial fibrillation by 31%, and ECG 3 was correctly identified as atrial flutter by 90%. Cardiology fellows and cardiologists correctly identified ECG 1 more often than house officers and internists (95% vs 63%; P < or = .01). ECG 2 was correctly identified by 26% of cardiology fellows and cardiologists and by 37% of house officers and internists (P = .10). ECG 3 was correctly identified by 91% of cardiology fellows and cardiologists and by 82% of house officers and internists (P = .06). In conclusion, atrial fibrillation is frequently misdiagnosed as atrial flutter. Misdiagnosis of atrial fibrillation occurs more often when atrial activity is prominent on an ECG in more than one lead.     

左房异常与心房颤动的关系

目的探讨左房异常与心房颤动发生的关系。方法应用心电图和动态心电图进行,持续性房颤患者为A组,阵发性房颤、房扑患者为B组,仅有心电图P波增宽的患者为C组,A、B、C三组各40例。所有入选患者均经超声心动图检测左房大小,观察患者窦性心律时心电图P波时限、切迹和P波离散度,并分析与房颤发生的关系。结果房颤男性多于女性,年龄大于60岁者94例(占78.3%),三组中86.7%的患者存在器质性心脏病(104例)。心电图P波切迹明显、P波离散度大者快速房颤发生率高;超声心动图检测左房直径大者房颤发生率高,持续性房颤比阵发性房颤患者左房直径大(p<0.05)。结论左房扩大、房内阻滞及P波离散度增大的患者易发生房颤。     

Importance of right and left atrial dilation and linear ablation for perpetuation of sustained atrial fibrillation

INTRODUCTION: Atrial dilation associated with increasing atrial pressure plays an apparent role in the development of atrial fibrillation (AF). We characterized a new model of separate and biatrial dilation in the Langendorff-perfused rabbit heart. The aim of this study was to examine if sustained AF in this model (1) would be inducible by separate right atrial (RA) and left atrial (LA) dilation; (2) would be reproducibly inducible at the same pressure level; and (3) could be suppressed by RA, LA, or biatrial ablation. METHODS AND RESULTS: Intra-atrial pressure was increased stepwise in the RA (n = 13), LA (n = 12), or both atria (n = 25) until sustained AF could be induced or a pressure of 20 cm H2O was reached. The stimulation protocol was repeated once in RA and LA dilation (n = 9) and three times in biatrial dilation (n = 7). Then, RA orifices (superior and inferior caval veins, tricuspid valve annulus, and foramen ovale) or LA orifices (pulmonary veins, mitral valve annulus, and foramen ovale) were connected by radiofrequency (RF) lesions. Sustained AF was rendered inducible in 100% of hearts with biatrial dilation, but in only 92% of hearts with RA dilation and 67% with LA dilation. Inducibility of sustained AF was reproducible. Under biatrial dilation, not RA ablation (0/10 hearts; P = NS) but LA ablation (4/11 hearts; P < 0.05) and biatrial ablation (16/21; P < 0.01) reduced the inducibility of sustained AF. CONCLUSION: The inducibility of sustained AF due to increased intra-atrial pressure differs between the RA and LA. LA and biatrial lesions, not RA RF lesions, reduce the ability to perpetuate sustained AF.     

Effect of gender on atrial electrophysiologic changes induced by rapid atrial pacing and elevation of atrial pressure

INTRODUCTION: The incidence of atrial fibrillation is greater in men than in women, but the reasons for this gender difference are unclear. The purpose of this study was to evaluate the effects of gender on the atrial electrophysiologic effects of rapid atrial pacing and an increase in atrial pressure. METHODS AND RESULTS: Right atrial pressure and effective refractory period (ERP) were measured during sinus rhythm and during atrial and simultaneous AV pacing at a cycle length of 300 msec in 10 premenopausal women, 11 postmenopausal women, and 24 men. The postmenopausal women were significantly older than the premenopausal women (61 +/- 8 years vs 34 +/- 10 years; P < 0.01). During sinus rhythm, mean atrial ERP in premenopausal women was shorter (211 +/- 19 msec) than in postmenopausal women and age-matched men (242 +/- 18 msec and 246 +/- 34 msec, respectively; P < 0.05). Atrial ERPs in all patients shortened significantly during atrial and simultaneous AV pacing. However, the degree of shortening during atrial pacing (43 +/- 8 msec vs 70 +/- 20 msec and 74 +/- 21 msec; P < 0.05) and during simultaneous AV pacing (48 +/- 16 msec vs 91 +/- 27 msec and 84 +/- 26 msec; P < 0.05) was significantly less in premenopausal women than in postmenopausal women or age-matched men. CONCLUSION: The results of this study demonstrate a significant gender difference in atrial electrophysiologic changes in response to rapid atrial pacing and an increase in atrial pressure. The effect of menopause on the observed changes suggests that the gender differences may be mediated by the effects of estrogen on atrial electrophysiologic properties.     

Simultaneous occurrence of atrial fibrillation and atrial flutter

INTRODUCTION: Early reports suggested that some patients with "atrial fibrillation/flutter" might have atrial fibrillation in one atrium and atrial flutter in the other. However, more recent conceptions of atrial fibrillation/flutter postulate that the pattern is due to a relatively organized (type I) form of atrial fibrillation. We report the occurrence and ECG manifestations of simultaneous atrial fibrillation and flutter in patients undergoing attempted catheter ablation of atrial flutter. METHODS AND RESULTS: In patients undergoing radiofrequency ablation for atrial flutter, an attempt was made to entrain atrial flutter by pacing in the right atrium. The arrhythmias observed occurred following attempts at entrainment, or spontaneously in one case. Twelve transient episodes of simultaneous atrial fibrillation and flutter were observed in five patients. The atrial fibrillation was localized to all or a portion of one atrium, during which the other atrium maintained atrial flutter. In each case, the surface 12-lead ECG reflected the right atrial activation pattern. No patients had interatrial or intra-atrial conduction block during sinus rhythm, suggesting functional intra-atrial block as a mechanism for simultaneous atrial fibrillation/flutter. CONCLUSION: In certain patients, the occurrence of transient, simultaneous atrial fibrillation and flutter is possible. In contrast to prior studies in which it was suggested that left atrial or septal activation determines P wave morphology, the results of the present study show that P wave morphology is determined by right atrial activation. Functional interatrial block appears to be a likely mechanism for this phenomenon.     

静脉地尔硫治疗快速房颤、房扑的疗效分析

为检验静脉地尔硫艹卓控制房颤、房扑心室率的有效性和安全性，对４７例快速房颤、房扑患者一次静脉注射０．２５ｍｇ／ｋｇ地尔硫艹卓后以５ｍｇ／ｈ～１０ｍｇ／ｈ微泵维持，平均起效时间５．２±２．７ｍｉｎ，总有效率９３．６％，心功能较用药前明显改善（Ｐ＜０．０５），对血压无明显影响，副作用发生率为１０．６％，均不严重。结果提示地尔硫艹卓是一种能迅速、安全、有效控制房颤、房扑患者心室率的药物     

Acute effects of left atrial radiofrequency ablation on atrial fibrillation

INTRODUCTION: Acutely, when left atrial ablation is performed during atrial fibrillation (AF), the AF may persist and require cardioversion, or it may convert to sinus rhythm or to atrial tachycardia/flutter. The prevalence of these acute outcomes has not been described. METHODS AND RESULTS: Left atrial ablation, usually including encirclement of the pulmonary veins, was performed during AF in 144 patients with drug-refractory AF. Conversion to sinus rhythm occurred in 19 patients (13%), to left atrial tachycardia in 6 (4%), and to atrial flutter in 6 (4%). In the 6 patients with a focal atrial tachycardia, the mean cycle length was 294 +/- 45 ms. The tachycardia arose in the left atrial roof in 3 patients, the left atrial appendage in 2, and the anterior left atrium in 1. In 3 of 6 patients, the focal atrial tachycardia originated in an area that displayed a relatively short cycle length during AF. In 6 patients, AF converted to macroreentrant atrial flutter with a mean cycle length of 253 +/- 47 ms, involving the mitral isthmus in 5 patients and the septum in 1 patient. All atrial tachycardias and flutters were successfully ablated with 1 to 15 applications of radiofrequency energy. CONCLUSION: When left atrial ablation is performed during AF, the AF may convert to atrial tachycardia or flutter in approximately 10% of patients. Focal atrial tachycardias that occur during ablation of AF may be attributable to driving mechanisms that persist after AF has been eliminated, whereas atrial flutter results from incomplete ablation lines.     

Effect of left atrial circumferential ablation for atrial fibrillation on left atrial transport function

BACKGROUND: The effects of left atrial (LA) circumferential ablation on LA function in patients with atrial fibrillation (AF) have not been well described. OBJECTIVES: The purpose of this study was to determine the effect of LA circumferential ablation on LA function. METHODS: Gated, multiphase, dynamic contrast-enhanced computed tomographic (CT) scans of the chest with three-dimensional reconstructions of the heart were used to calculate the LA ejection fraction (EF) in 36 patients with paroxysmal (n = 27) or chronic (n = 9) AF (mean age 55 +/- 11 years) and in 10 control subjects with no history of AF. Because CT scans had to be acquired during sinus rhythm, a CT scan was available both before and after (mean 5 +/- 1 months) LA circumferential ablation (LACA) in only 10 patients. A single CT scan was acquired in 8 patients before and in 18 patients after LACA ablation. Radiofrequency catheter ablation was performed using an 8-mm-tip catheter to encircle the pulmonary veins, with additional lines along the mitral isthmus and the roof. RESULTS: In patients with paroxysmal AF, LA EF was lower after than before LACA (21% +/- 8% vs 32 +/- 13%, P = .003). LA EF after LA catheter ablation was similar among patients with paroxysmal AF and those with chronic AF (21% +/- 8% vs 23 +/- 13%, P = .7). However, LA EF after LA catheter ablation was lower in all patients with AF than in control subjects (21% +/- 10% vs 47% +/- 5%, P < .001). CONCLUSION: During medium-term follow-up, restoration of sinus rhythm by LACA results in partial return of LA function in patients with chronic AF. However, in patients with paroxysmal AF, LA catheter ablation results in decreased LA function. Whether the impairment in LA function is severe enough to predispose to LA thrombi despite elimination of AF remains to be determined.     

Termination of persistent atrial fibrillation during left atrial mapping

Termination of Persistent AF During Mapping. Complex fractionated atrial electrograms (CFAEs) may represent critical areas for the maintenance of atrial fibrillation (AF). While AF organization and termination have been reported with CFAE ablation, no reports of arrhythmia termination during left atrial mapping exist. We report a case of reproducible AF termination with catheter pressure at a site of CFAE remote from the site of AF. (J Cardiovasc Electrophysiol, Vol. 22, pp. 1171‐1173, October 2011)     

立体心电图分析阵发性房颤患者心房的电生理特性

目的应用立体心电图(three-dimensional electrocardiogram,3D-ECG)分析阵发性房颤患者心房传导时间、心房除极角度和振幅的变化。方法入选在住院的阵发性房颤患者13例,对照组患者15例。分别应用立体心电图仪记录窦律下的立体心电图,分析后比较两组患者心房传导时间,P波除极振幅及角度。同时记录患者入院时超声心动图中左心房内径数值进行比较。结果两组患者比较左心房内径无显著差异。阵发性房颤组与对照组心房传导时间分别为123.75±11.67msvs.111.39±13.52ms,两组比较有显著性差异(p<0.05)。而在心房除极角度、振幅上,两组无显著差异。与对照组比较,阵发性房颤组患者P环初始部的运行方向与泪点疏密程度无明显变化,但在P环中间至终末部分,P环运行方向及泪点疏密出现明显变化,并且可看到明显的曲折、弯曲。但在除极末20ms的振幅,房颤患者较对照组明显降低(0.05±0.013mvvs.0.036±0.014mv,p<0.05),除极末30ms、40ms处两组振幅无显著差异。结论阵发性房颤患者可以出现心房传导时间延长、心房除极末振幅的改变和立体三维P环运行方向及泪点疏密程...     

Effects of simultaneous atrioventricular pacing on atrial refractoriness and atrial fibrillation inducibility: role of atrial mechanoelectrical feedback

INTRODUCTION: The purpose of this study was to evaluate the effects of an acute increase in atrial pressure on refractoriness (mechanoelectrical feedback) and the vulnerability to atrial fibrillation (AF) and to investigate the effects of autonomic blockade and verapamil on mechanoelectrical feedback in humans. METHODS AND RESULTS: Right atrial pressure and effective refractory period (ERP) at the right atrial appendage (RAA) and high right atrial septum were measured during sinus rhythm, and during atrial and simultaneous AV pacing at a cycle length of 300 msec, either in the absence (n = 25) or presence (n = 22) of pharmacologic autonomic blockade. In another 15 patients, the protocol was performed before and after infusion of verapamil 0.15 mg/kg. In the absence of autonomic blockade, AV pacing resulted in a higher mean right atrial pressure (11.7 +/- 3.3 vs 4.3 +/- 3.0 mmHg, P < 0.001) and a shorter atrial RAA ERP (144 +/- 23 msec vs 161 +/- 21 msec; P < 0.001) compared with atrial pacing; AF was induced more often during AV pacing (87%) than during atrial pacing (20%) and was related directly to the right atrial pressure (r = 0.39, P = 0.004) and indirectly to the RAA ERP (r = -0.42, P < 0.001). The susceptibility to sustained AF was greatly enhanced by autonomic blockade. Verapamil markedly attenuated the shortening of ERP and the propensity for AF that occurred during simultaneous AV pacing. CONCLUSION: An acute increase in atrial pressure during tachycardia is associated with shortening of atrial refractoriness and a propensity for AF, i.e., atrial mechanoelectrical feedback, which may be enhanced by autonomic blockade and attenuated by calcium channel blockade.     

心房粘液瘤对心房除极的影响

为探讨心房粘液瘤对心房激动过程的影响,对19例左心房粘液瘤和2例右心房粘液瘤的VCG高倍P环(1mV=360mm)进行测量,结果显示不同部位粘液瘤对心房激动的影响不同,VCGP环亦不同.左心房粘液瘤P环时限延长,除左心房肥大外,较容易判断出双侧心有肥大、房内传导阻滞.右心房粘液瘤P环时限正常,仅表现右心房肥大.VCG上放大的P环能比ECG上P波更敏感地反映出心房异常活动的电变化.     

Use of fast fourier transform analysis of atrial electrograms for rapid characterization of atrial activation-implications for delineating possible mechanisms of atrial tachyarrhythmias

INTRODUCTION: Different analysis techniques have been developed to help understand and characterize the mechanisms responsible for atrial arrhythmias. We tested the hypothesis that Fast Fourier Transform (FFT) analysis of recorded atrial electrograms (AEGs) will rapidly and accurately identify regular and irregular patterns of atrial activation, and, thereby, may provide evidence suggestive of underlying mechanisms of atrial tachyarrhythmias. METHODS AND RESULTS: During induced atrial tachyarrhythmias in both the canine sterile pericarditis model and canine rapid ventricular pacing-induced congestive heart failure model; 380-404 AEGs were recorded simultaneously from epicardial electrodes on both atria. From AEGs, atrial activation sequences were determined during atrial flutter (AFL), focal atrial tachycardia (AT), and atrial fibrillation (AF). Four-second recording segments of each AEG were subjected to FFT analysis. Frequencies found during FFT analyses in all studies precisely corresponded to the cycle lengths of the AEGs. In AFL and AT, one dominant frequency peak was found throughout both atria. In AF due to multiple unstable reentry circuits, multiple and broad frequency peaks were found in both atria. In AF due to a stable rapid rhythm (driver) in the left atrium with fibrillatory conduction to the rest of the atria, one dominant frequency peak in areas with 1:1 conduction from the driver, and multiple and/or broad frequency peaks in areas with fibrillatory conduction produced by the driver were found. Computation time for all FFT analyses took <5 minutes. CONCLUSION: FFT analysis accurately and rapidly identifies global atrial activation patterns during AFL, AT, and AF, thereby assisting in determining arrhythmia mechanisms.     

房颤犬心房间质重塑的相关细胞因子表达

目的研究房颤与心房结构重构的关系以及心房结构重构对心脏间质细胞调控相关的TGFB1,FGFR一1,VEGF等相关细胞因子表达的影响。方法实验动物随机分为三组：房颤式起搏组、T型钙通道阻滞剂组、正常对照组,24周后取其心房组织进行免疫组化染色,然后使用图像软件测量并比较I型胶原和TGFβ,FGFR—l,VEGF的表达量;分析3组犬心房调控因子与I型胶原蛋白表达量的相关性。结果房颤式起搏组的I型胶原表达量明显高于T型钙通道阻滞剂组和正常对照组。房颤式起搏组和正常对照组的心房组织TGF131表达与I型胶原有统计学相关性,而T型钙通道阻滞剂组无统计学相关性;三组心房组织的FGFR一1、VEGF表达量与I型胶原均无统计学相关性。结论持续性房颤可能导致心房发生明显的结构重塑,TGFβ1能具有很强的致心房纤维化作用。     

Electroanatomic characteristics of atrial premature beats triggering atrial fibrillation in patients with persistent versus paroxysmal atrial fibrillation

APBs in Persistent Versus Paroxysmal AF. BACKGROUND: Although the electrical disconnection between the left atrium (LA) and pulmonary veins (PVs) by radiofrequency catheter ablation has been proven to be effective in controlling atrial fibrillation (AF), the recurrence rate is higher in patients with persistent AF (PeAF) than with paroxysmal AF (PAF). We hypothesized that the origin of the atrial premature beats (APBs) that trigger AF and the pattern of their breakthrough into the LA differ between PAF and PeAF. METHODS: We mapped 75 APBs (53 APBs triggering AF, 22 isolated APBs) from the LA and PVs in 26 patients with AF (age: 49.5 +/- 9.6, males: 23, PAF = 17, PeAF = 9), using a noncontact endocardial mapping (NCM) system. The location of the preferential conduction (PC) sites and their conduction velocity (CV) were compared. RESULTS: In patients with PeAF, the earliest activation (EA) site and exit of the PC were more frequently located on the LA side of the LA-PV junction as compared with PAF (P < 0.001). Eighty-one percent of the PCs were located in the area between the left and right superior PVs. The incidence of PCs was similar between the PeAF and PAF patients (P = NS). PCs were more commonly found with APBs inducing AF (63.3%) than with those not inducing AF (35.2%, P = 0.01). The CV of the PC was slower for PeAF than PAF (P < 0.001). The CV in the LA during sinus rhythm was also slower for PeAF than PAF (P < 0.01). CONCLUSION: PeAF was more frequently triggered by APBs from the LA side of the LA-PV junction than PAF and resulted in slower conduction than did PAF. These findings may help explain the higher potential for recurrence after electrical PV isolation in patients with PeAF.     

食管心房调搏诱发阵发性房颤的心房电生理特性

为了探讨食管心房调搏对阵发性房颤检查的临床价值。回顾食管心房调搏诱发２５例阵发性房颤的心房电生理特性。其结果；程序刺激，分级起搏诱发１１例房颤，均有明确的房颤 史，猝发电脉冲诱发的１４例中１０例有明确的房颤史。房颤组２５例与正常对照组２５例相比心房有效不应期缩短，相对不应期区域扩大，最大房间传导时间延长，房间传导延缓更显著，这些可能是食管心房调搏诱发房颤的重要电生理基础。认为食管心房调搏对确定临床     

Effects of verapamil and ibutilide on atrial fibrillation and postfibrillation atrial refractoriness

INTRODUCTION: Early recurrence of atrial fibrillation (AF) after cardioversion may be related to shortening of the atrial effective refractory period (ERP). This study compared the effects of verapamil and ibutilide on AF cycle length (AFCL), atrial ERP, and susceptibility to recurrent AF. METHODS AND RESULTS: In 33 adults, the atrial ERP was measured at basic drive CLs of 350 and 500 msec before and after a brief episode of pacing-induced AF. During AF, verapamil, ibutilide, or saline was infused in 11 patients each. Shortening of the post-AF atrial ERP was attenuated by verapamil and prevented by ibutilide. AFCL shortened by 32+/-21 msec in the verapamil group (P < 0.01), prolonged by 44+/-14 msec in the ibutilide group (P < 0.001), and did not change in the control group. AF converted to sinus rhythm within 10 minutes less often after verapamil (0%) than after ibutilide (82%) or than in the control group (73%). Post-AF, AF lasting > 10 minutes was induced more often in the verapamil group than in the ibutilide group (26% vs 0%; P = 0.01). Another 10 patients received verapamil or ibutilide in the absence of AF. Atrial ERP was unchanged after verapamil and prolonged after ibutilide. CONCLUSION: Verapamil shortens AFCL and impedes the conversion of induced AF, whereas ibutilide prolongs AFCL and does not impede the early conversion of induced AF. Ibutilide is more effective than verapamil in preventing pos