Comparison of the acute effects of pacing the atrial septum, right atrial appendage, coronary sinus os, and the latter two sites simultaneously on the duration of atrial activation

OBJECTIVE—To compare the acute effects of right atrial appendage, atrial septal, coronary sinus os, and dual site pacing on the duration of atrial activation.
METHODS—20 patients with a variety of cardiac conditions underwent an intracardiac electrophysiological study. Electrograms were recorded from the right atrial appendage and at multiple sites within the coronary sinus. The duration of atrial activation was measured during pacing at the right atrial appendage, atrial septum, and coronary sinus os, and also during dual site stimulation.
RESULTS—The duration of atrial activation with atrial appendage pacing was notably longer (p < 0.001) than with dual site, septal, or coronary sinus os pacing, but there were no significant differences in atrial activation times between these latter three pacing modes. When stimulating the atria at a cycle length of 500 ms, the mean (SD) duration of atrial activation was 145 (37) ms for right atrial appendage pacing, 93 (26) ms for dual site pacing, 96 (28) ms for septal pacing, and 98 (28) ms for coronary sinus os pacing.
CONCLUSIONS—Assuming that the duration of atrial activation is an important determinant of predisposition to paroxysmal atrial fibrillation, atrial septal pacing or coronary sinus os pacing would appear to offer the same advantage as dual site pacing without the additional complexities associated with the latter pacing mode.


Keywords: atrial septal pacing; dual site pacing; atrial activation; atrial fibrillation     

The Impact of the Distance between the Atrial Electrode and the Atrial Wall on Atrial Undersensing in Patients with VDD Pacemakers: Long‐Term Follow‐Up

Aim: Atrial undersensing (AUS) in single‐lead VDD pacemakers may be due to diminished P‐wave amplitude secondary to local inflammation beneath the electrodes closer to atrial wall. The aim of this study was to assess the potential effect of distance between atrial electrode and atrial wall on immediate and long‐term atrial sensing stability in VDD systems. Methods: A total of 275 patients with normal sinus node function who received VDD pacemakers were enrolled into the study and were followed up for a median duration of 33 months. During each control visit, a standard 12‐lead electrocardiogram (ECG) was obtained and standard pacemaker function assessment was performed including testing for pacing threshold and atrioventricular synchrony. The distance between atrial electrode and atrial wall was measured from chest X‐ray. Results: Of the 275 patients, AUS was detected in 59 patients. Univariate predictors of AUS were use of closely spaced bipolar ring atrial electrode (CSBR) (P = 0.01), wider atrial ring‐spacing (P = 0.03), and atrial sensitivity programmed to a higher level (P = 0.001). Use of CSBR (P = 0.04) and atrial sensitivity ≥0.3 mV (P = 0.02) were observed to be the independent predictors for AUS. When the distance between atrial electrode and atrial wall was <7 mm, AUS was less with diagonally arranged bipolar ring electrodes (DABR) than it was with CSBRs (P = 0.02). Conclusions: The distance between atrial electrode and atrial wall does not appear to affect AUS incidence in VDD pacemakers. For VDD electrodes closer to atrial wall, AUS was significantly less likely in DABR‐type electrodes.     

Atrial Electrograms and Activation Sequences in the Transition Between Atrial Fibrillation and Atrial Flutter

Transition Between Atrial Fibrillation and Flutter. Introduction: The eletrophysiologic mechanism of atrial fibrillation (AF) has a wide spectrum, and it seems that some atrial regions are essential for the occurrence of a particular type of AF. We focused on one type of AF: AF associated with typical atrial flutter (AFI), which was right atrial (RA) arrhythmia, and sought to investigate intra-atrial electrograms and activation sequences in the transition between AF and AFL.
Methods and Results: Intra-atrial electrograms and activation sequences in the R.A free wall and the septum were evaluated in the transition between AF and AFL in seven patients without organic heart disease (all men; mean age 57 ± 11 years). In five episodes of the conversion of AFL into AF, the AFL cycle length was shortened (from 211 ± 6 msec in stable AFL to 190 ± 15 msec before the conversion, P, 0.001). Interruption of the AFL wavefront and an abrupt activation sequential change induced by a premature atrial impulse resulted in fractionation and disorganization of the septal electrograms. During sustained AF, septal electrograms were persistently fractionated with disorganized activation sequences. However, the RA free-wall electrograms were organized, and the activation sequence was predominantly craniocaudal rather than caudocranial throughout AF. In 12 episodes of the conversion of AF into AFL, the AF cycle length measured in the RA free wall increased (from 165 ± 26 msec at the onset of AF to 180 ± 24 msec before the conversion, P, 0.001). AFL resumed when fractionated septal electrograms were separated and organized to the caudocranial direction, despite the RA free-wall electrograms remaining discrete and sharp with an isoelectric line.
Conclusion: Changes of the electrogram and activation sequence in the atrial septum played an important role in the transition between AF and AFL.     

Reduced Peak Atrial Systolic Mitral Annular Velocity Predicts the Development of Nonvalvular Atrial Fibrillation

We investigated whether the echocardiographic parameters of the left atrium (LA) can predict the development of nonvalvular atrial fibrillation (AF). Among 14,062 patients ( > 20 years old) who underwent an echocardiographic examination were evaluated, 2,606 patients who underwent follow-up ECG with an interval of > 6 months were investigated. Newly developed AF was noted in 42 (1.6%) patients with follow-up duration of 31.8 ± 8.9 months. Cox regression analysis revealed that a higher left atrial volume index (hazard ratio [HR ]= 1.06; 95% confidence interval [CI] 1.03–1.09, P < 0.001), relative wall thickness (RWT) of ≥ 0.407 (HR = 2.74, 95% CI 1.39–5.41, P = 0.004), a reduced peak atrial systolic mitral annular velocity (HR = 0.845, 95% CI 0.72–0.99, P = 0.037), and an advanced age (HR = 1.04, 95% CI 1.01–1.07, P = 0.009) were independently related to the development of nonvalvular AF. Therefore, reduced A ' , which is parameter of LA contractile function, might be an important predictor for the development of nonvalvular AF.     

Atrial tachycardia originating from the upper left atrial septum: demonstration of transseptal interatrial conduction using the infolded atrial walls

We report a rare case of atrial tachycardia (AT) originating from the upper left atrial septum. Electroanatomic mapping of both atria demonstrated that the earliest atrial activation during AT occurred at the upper left atrial septum 26 msec before the onset of the P wave, followed by the mid-right atrial septum (10 msec before the onset of the P wave) and then the upper right atrial septum just adjacent to the left septal AT site (1 msec before the onset of the P wave), indicating detour pathway conduction from the upper left to the upper right atrium. Embryologically, it was suggested that the superior components of the secondary atrial septum are made by the infolded atrial walls and could develop a transseptal detour pathway involving the left-side atrial septal musculature, the superior rim of the oval fossa and the right-side atrial septal musculature. A single radiofrequency application targeting the upper left atrial septum successfully abolished the AT.     

持续性心房颤动患者无症状心房颤动的发生情况及影响因素

Objective To investigate the incidence of asymptomatic atrial fibrillation( AF) and the influence factors in patients with persistent AF. Methods A total of 82 consecutive patients with 24 h Holter monitoring identified persistent AF were observed to analyze the incidence of asymptomatic AF. 24 h Holter monitoring was performed again after three months' treatment with antiarrythmic drugs in order to identify the incidence of asymptomatic AF. Multivariate logistic regression was applied for analyzing the correlation between symptoms and clinical features. Results Thirty-four patients(42% )were asymptomatic ,24 patients were symptomatic. After antiarrythmic drugs therapy for three months, 31 patients among 48 symptomatic patients, were completely asymptomatic, 4 were converted to sinus rhythm, 27 were asymptomatic atrial fibrillation. In 34 asymptomatic patients, 5 were converted to sinus rhythm, 24 remain asymptomatic atrial fibrillation. Significant differences were found between symptomatic and asymptomatic patients with persistent AF between age and valvular heart disease( P ＜ 0. 05 ). Symptoms were positively with valvular heart disease (b = 1. 959, P = 0. 001 ),and negatively with age( b = -0. 837,P = 0. 032). Conclusion The incidence of asymptomatic persistent AF was high. Antiarrythmic drugs could not only relieve the episodes of AF, but also the symptoms of AF. Elderly and nonvalvular atrial fibrillation(NVAF) patients were often asymptomatic.     

A Prospective Randomized Study to Assess the Efficacy of Rate and Site of Atrial Pacing on Long-Term Development of Atrial Fibrillation

The Septal Pacing for Atrial Fibrillation Suppression Evaluation (SAFE) study is a single-blinded, parallel randomized designed multicenter study in pacemaker indicated patients with paroxysmal atrial fibrillation (AF). The objective is to evaluate whether the site of atrial pacing–-conventional right atrial appendage versus low atrial septal—with or without atrial overdrive pacing will influence the development of persistent AF. The study will provide a definitive answer to whether a different atrial pacing site or the use of AF suppression pacing or both can give incremental antiarrhythmic benefit when one is implanting a device for a patient with a history of paroxysmal AF.     

心房晚电位检测的临床意义探讨

对61例非发作期房性心律失常病人和60例健康人进行信号平均心电图检测,并对部分患者作经食管电生理刺激以诱发房颤.结果显示;阵发性房颤组的滤波后P波时限和滤波后P波终末20ms均方根电压与正常组有显著性差异.提示滤波后P波时限与房颤有密切关系.该参数尚能反映病变的严重程度,并初步探讨了国人心房晚电位的诊断标准,认为滤波后P波时限>110ms且滤波后P波终末20ms均方根电压<3.5μV为心房晚电位阳性.     

Surgical clip closure of the left atrial appendage

Atrial fibrillation (AF) is the most common atrial arrhythmia, but it is not a benign disease. AF is an important risk factor for thromboembolic events, causing significant morbidity and mortality. The left atrial appendage (LAA) plays an important role in thrombus formation, but the ideal management of the LAA remains a topic of debate. The increasing popularity of surgical epicardial ablation and hybrid endoepicardial ablation approaches, especially in patients with a more advanced diseased substrate, has increased interest in epicardial LAA management. Minimally invasive treatment options for the LAA offer a unique opportunity to close the LAA with a clip device. This review highlights morphologic, electrophysiologic, and surgical aspects of the LAA with regard to AF surgery, and aims to illustrate the importance of surgical clip closure of the LAA.     

原发性高血压并发阵发性房颤心房结构和功能的研究

目的应用声学定量(AQ)技术,探讨高血压病有无阵发性房颤(PAF)时左心房结构和功能的变化并筛选高血压病PAF的超声危险因素。方法83例高血压病患者按PAF、有无分为两组,对比分析两组的一般临床特征及声学定量指标。结果PAF组左房内径、左房内径指数、各时相左房容积(EDV、ESV、EREV、OAEV)均明显大于无PAF组,与无PAF组相比,PAF组左房储存器容积(RV)显著增大,LAEF明显降低[RV:(64.61±18.64)vs(49.35±18.43)ml,P<0.001;LAEF:(0.44±0.16)vs(0.54±0.15),P<0.01)。结论与高血压无PAF者相比,高血压伴。PAF者左房容积增大,储存器功能增强,左房助力泵功能减低;左房增大和左房收缩功能减低是高血压病发生PAF的危险因素。     

Heterogeneous changes in electrophysiologic properties in the paroxysmal and chronically fibrillating human atrium

INTRODUCTION: The regional changes in atrial electrophysiologic properties related to atrial fibrillation (AF) in patients with paroxysmal AF (PAF) and chronic AF (CAF) remain unclear. The purpose of this study was to investigate the regional changes in atrial electrophysiology in patients with AF. METHODS AND RESULTS: We evaluated the atrial electrophysiology at different sites (high right atrium, low right atrium [LRA], and distal coronary sinus [DCS]) in 11 patients with CAF, 8 patients with PAF, and 10 controls. Patients with CAF had significantly prolonged interatrial conduction and corrected sinus node recovery time, and shortened atrial effective refractory period (ERP) with loss of rate-related adaptation in the DCS, but had paradoxic prolongation of atrial ERP in the LRA, as compared with patients with PAF and the controls. As a result, the spatial distribution of atrial ERP that was observed in the controls and in patients with PAF was reversed in patients with CAF, without an increase in the dispersion of atrial refractoriness. Patients with PAF showed intermediate changes in atrial conduction times and atrial refractoriness as compared with patients with CAF and controls. CONCLUSION: There was a regional heterogeneity on the changes of atrial electrophysiology in different parts of the atrium, and the "normal" spatial distribution of atrial refractoriness was reversed in patients with CAF. The electrophysiologic changes observed in patients with PAF appear to behave as if in transition from the control state to CAF, suggesting progressive changes in atrial electrophysiologic properties.     

持续性心房颤动患者无症状心房颤动的发生情况及影响因素

Objective To investigate the incidence of asymptomatic atrial fibrillation( AF) and the influence factors in patients with persistent AF. Methods A total of 82 consecutive patients with 24 h Holter monitoring identified persistent AF were observed to analyze the incidence of asymptomatic AF. 24 h Holter monitoring was performed again after three months' treatment with antiarrythmic drugs in order to identify the incidence of asymptomatic AF. Multivariate logistic regression was applied for analyzing the correlation between symptoms and clinical features. Results Thirty-four patients(42% )were asymptomatic ,24 patients were symptomatic. After antiarrythmic drugs therapy for three months, 31 patients among 48 symptomatic patients, were completely asymptomatic, 4 were converted to sinus rhythm, 27 were asymptomatic atrial fibrillation. In 34 asymptomatic patients, 5 were converted to sinus rhythm, 24 remain asymptomatic atrial fibrillation. Significant differences were found between symptomatic and asymptomatic patients with persistent AF between age and valvular heart disease( P ＜ 0. 05 ). Symptoms were positively with valvular heart disease (b = 1. 959, P = 0. 001 ),and negatively with age( b = -0. 837,P = 0. 032). Conclusion The incidence of asymptomatic persistent AF was high. Antiarrythmic drugs could not only relieve the episodes of AF, but also the symptoms of AF. Elderly and nonvalvular atrial fibrillation(NVAF) patients were often asymptomatic.     

Development and Validation of Diagnostic Criteria for Atrial Flutter on the Surface Electrocardiogram

Background: There are no universally accepted ECG diagnostic criteria for atrial flutter (AFL), making its differentiation from “coarse” atrial fibrillation (AF) difficult. Methods: To develop diagnostic criteria for AFL, we examined two sets of ECGs. Set 1 consisted of 100 ECGs (50 AF, AFL) with diagnoses confirmed by intracardiac recordings. Criteria evaluated were presence of F waves in the frontal plane leads, F waves in V₁, sawtooth F waves, rate, and regularity of ventricular response. Set 2 included 200 ECGs taken from the hospital database each of which had already been interpreted by a cardiologist as either AF (n = 100) or AFL (n = 100). Set 2 was blindly read by electrophysiologists whose consensus‐diagnoses were compared to the diagnoses made by using the best criteria identified from the Set 1 data. Results: The criteria of frontal plane F waves, regular or partially regular ventricular response, and their combination had sensitivities of 92%, 98%, and 90% and specificities of 100%, 78%, and 100% in Set 1 for the diagnosis of AFL. In Set 2, concordance of electrophysiologist and cardiologist diagnoses was only 84%. The criteria of frontal plane Fwaves, regular or partially regular ventricular response, and their combination resulted in concordances with the cardiologist diagnoses of 85%, 85%, and 82% and with the electrophysiologist‐consensus diagnoses of 90%, 89%, and 94% (P < 0.001). Conclusions: The criteria of frontal plane F waves and regular or partially regular ventricular response aid in the proper diagnosis of AFL. Because management strategies may differ for AF and AFL, it is important to adopt a more rigorous diagnostic approach.     

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.     

Beware of the LASP! A structure with thrombogenic potential

The left atrial septal pouch (LASP) is a recently identified anatomical variant of the interatrial septum. It is the result of the incomplete fusion of septum primum and septum secundum and defined as a recessus communicating with the left atrium without interatrial shunt. Such anatomical feature has been suspected representing a potential thrombogenic source, but its actual role as risk factor for cryptogenic stroke still remains unclear. In this case report, we show two distinct thrombotic masses emerging from the LASP and its related areas.     

Role of repolarization restitution in the development of coarse and fine atrial fibrillation in the isolated canine right atria

INTRODUCTION: Although the role of action potential duration restitution (APD-R) in the initiation and maintenance of ventricular fibrillation (VF) has been the subject of numerous investigations, its role in the generation of atrial fibrillation (AF) is less well studied. The cellular and ionic basis for coarse versus fine AF is not well delineated. METHODS AND RESULTS: We measured APD-R during acetylcholine-mediated AF as well as during pacing (standard and dynamic protocols) in crista teriminalis, pectinate muscle, superior vena cava, and appendage of isolated canine arterially perfused right atria (n = 15). Transmembrane action potential (TAP), pseudo-ECG, and isometric tension development were simultaneously recorded. Acetylcholine flattened APD-R measured by both standard and dynamic protocols, but promoted induction of AF. AF was initially coarse, converting to fine within 3-15 minutes of AF. Coarse, but not fine AF was associated with dramatic fluctuations in tension development, reflecting wide variations in intracellular calcium activity ([Ca(2+)](i)). During coarse AF, APD-R data displayed a cloud-like distribution pattern, with a wide range of maximum APD-R slope (from 1.21 to 0.35). A maximum APD-R slope >1 was observed only in crista terminalis (3/10). The APD-R relationship was relatively linear and flat during fine AF. Reduction of [Ca(2+)](i) was associated with fine AF whereas augmentation of [Ca(2+)](i) with coarse AF. CONCLUSIONS: Our data indicate that while APD-R may have a limited role in the maintenance of coarse AF, it is unlikely to contribute to the maintenance of fine AF and that [Ca(2+)](i) dynamics determine the degree to which AF is coarse or fine.     

Clinical Significance of the Left Atrial Appendage Orifice Area

Objective The left atrial appendage (LAA) is one of the major sources of cardiac thrombus formation. Three-dimensional transesophageal echocardiography (TEE) made it possible to perform a detailed evaluation of the LAA morphologies. This study aimed to evaluate the clinical implications of the LAA orifice area. Methods A total of 149 patients who underwent TEE without significant valvular disease were studied. The LAA orifice area was measured using three-dimensional TEE. The patients were divided into two groups according to the LAA orifice area (large LAA orifice group, ≥median value, and small LAA orifice group). The clinical characteristics and echocardiographic findings were evaluated. Results The median LAA orifice area among all patients was 4.09 cm² (interquartile range 2.92-5.40). The large LAA orifice group were older (67.2±10.4 vs. 62.4±15.3 years, p=0.02), more often had hypertension (66.7% vs. 44.6%, p=0.007), and atrial fibrillation (70.7% vs. 39.2%, p＜0.001) than the small LAA orifice group. Regarding the TEE findings, the LAA flow velocity was significantly lower (33.7±20.0 vs. 50.2±24.3, p＜0.001) and spontaneous echo contrast was more often observed (21.3% vs. 8.1%, p=0.02) in the large LAA orifice group. Multivariate models demonstrated that atrial fibrillation was an independent predictor of the LAA orifice area. In the analysis of atrial fibrillation duration, the LAA orifice area tended to be larger as patients had a longer duration of atrial fibrillation. Conclusion Our findings indicated that a larger LAA orifice area was associated with the presence of atrial fibrillation and high thromboembolic risk based on TEE findings. A continuation of the atrial fibrillation rhythm might lead to the gradual expansion of the LAA orifice.