Monophasic action potentials of the right atrium during atrial fibrillation in man.

In 28 patients with established atrial fibrillation [AF], right atrial monophasic action potentials [MAP] were recorded before DC shock. A close correlation was found between the atrial rate and MAP duration of the fibrillatory waves [FW]. The duration of MAPs ranged between 1 and 6 mV. The atrial rate ranged between 311 and 578 per minute, the highest rates were found during lone AF. In two patients in whom cardioversion failed, a prolongation of right atrial MAP duration of the FW was noted. The efficacy of DC shock and the maintenance of sinus rhythm after cardioversion was greater in patients with AF having a slower rate and a longer MAP.     

心房颤动患者心房肌动作电位时程频率适应性研究

目的　研究阵发性孤立性心房颤动 (房颤 )患者及对照组心房肌动作电位时程 (APD)频率适应性的差异 ,阐明其与房颤发生有关的可能机制。方法　应用同时具有起搏功能的Ag AgCl电极记录单向动作电位 (MAP) ,房颤组和对照组各入选 11例患者 ,在逐渐递减的 9个起搏周长分别记录MAP并测量APD90 、APD90 50 。所有房颤患者MAP记录前 1个月无房颤发作史 ,以排除电重塑影响。结果　在较长起搏周长 (6 0 0、5 5 0、5 0 0ms) ,房颤组APD90 显著短于对照组 (P <0 0 5 ) ;在较短起搏周长(340、30 0、2 80ms) ,房颤组APD90 又显著长于对照组 (P <0 0 5 )。同样APD90 50 在较长起搏周长 (6 0 0、5 5 0、5 0 0、4 6 0ms) ,房颤组显著短于对照组 (P <0 0 5 ) ;而较短起搏周长 (340、30 0、2 80ms)两组无差别。结论　心房肌APD频率适应性曲线在阵发性孤立性房颤组与对照组有所不同 ,其可能与房颤的最初发生和维持有关 ,机制存在于离子通道水平。     

Monophasic action potentials of right atrium and electrophysiological properties of AV conducting system in patients with hypothyroidism.

In 12 patients with manifest hypothyroidism right atrial monophasic action potentials showed a significant prolongation in comparison with data from normal or euthyroid patients. Atrial effective refractory periods were also significantly prolonged. After thyroid treatment the monophasic action potential duration and the effective refractory period of the right atrium were within normal ranges. In 6 hypothyroid patients studies of AV conduction with the aid of His bundle electrography and atrial pacing showed a supraHisian conduction delay which was manifest in one case and latent in another two. InfraHisian conduction delay was encountered in 2 cases.     

Electrophysiologic characteristics of paroxysmal and chronic atrial fibrillation in human right atrium

OBJECTIVES: The aim of the study was to analyze the electrophysiologic characteristics of paroxysmal (PAF) and chronic (CAF) atrial fibrillation (AF) in the human right atrium (RA). BACKGROUND: Differences that exist between PAF and CAF and the mechanisms of self-sustenance of these arrhythmias are incompletely understood. METHODS: A total of 53 patients with PAF (25 patients, mean age 59 +/- 6.1 years, 3 women) and CAF (28 patients, mean age 59 +/- 13 years, 7 women) underwent multisite mapping of the RA during ongoing AF using a 64-electrode basket catheter. Quantitative evaluation and three-dimensional activation patterns were performed using a computerized system. RESULTS: Patients with PAF, as compared with patients with CAF, had significantly longer AF cycle length, shorter time intervals with type III AF throughout the RA and a smaller number of endocardial breakthroughs (mean 51 +/- 19 vs. 104 +/- 40, p < 0.001). The majority of endocardial breakthrough points (88% in PAF patients and 98% in CAF patients) were located in the septal region and coincided anatomically with major interatrial connection routes. Coexistence of re-entrant and apparently focal activation determined maintenance of AF in the RA in PAF, whereas random re-entry was documented more frequently in patients with CAF. In patients with CAF, the duration of arrhythmia (in years) correlated strongly with the percentage of time during which type III AF was observed in the lateral wall of the RA (r = 0.71). CONCLUSIONS: Clinical PAF and CAF, as recorded in the RA, have, at least quantitatively, distinct electrophysiologic features and different mechanisms of maintenance.     

双心房右心室起搏器治疗阵发性心房颤动的临床应用

目的　观察双心房右心室三腔起搏治疗快速性房性心律失常的临床效果。探讨双心房右心室三腔起搏运用的原理 ,适应证以及起搏模式的选择。方法　患者 6例 ,男性 4例 ,女性 2例 ,诊断 :阵发性心房颤动、房间传导阻滞。置入双心房右心室三腔起搏器。左心房起搏通过冠状静脉窦植入 2 188电极导线 ,左右心房电极导线通过 Y形转接器与双腔起搏器连接。结果　双心房同步起搏后 ,患者阵发性心房颤动的发作明显减少。结论　初步临床应用提示 ,右心室三腔起搏器双心房同步起搏治疗阵发性心房颤动有效。     

Prolonged atrial activity due to delayed conduction in the atrium of patients with paroxysmal atrial fibrillation

Summary We investigated the relationship between the duration of electrical atrial activity and intra-atrial conduction time to determine whether the prolonged atrial activity was due to delayed conduction in the human atrium. The study included 15 patients with paroxysmal atrial fibrillation (PAF) and 15 control patients. The duration of atrial electrical activity was measured by selecting a minimum electrographic amplitude of 50µV. In patients with PAF, the duration of atrial activity was prolonged in proportion to the delay of interatrial conduction time from the high right atrium to the coronary sinus as the coupling interval of premature extrastimuli was decreased. Both the fragmented atrial activity zone and the interatrial conduction delay zone were wider in patients with PAF than in control patients. It is concluded that assessment of the duration of atrial activity with a minimum amplitude of 50µV is useful in evaluating human atrial vulnerability since it reflects the atrial conduction delay in patients with PAF.     

Impaired transport function of the left atrium in patients with lone paroxysmal atrial fibrillation

Background: Although lone paroxysmal atrial fibrillation (LPAF) is clinically defined as an arrhythmia that occurs in the absence of structural heart disease, it has been suggested that the presence of anatomical substrate is related to LPAF. The aim of the present study is to determine whether structural and functional remodeling of the left atrium (LA) occurs in patients with LPAF, and to identify whether frequent episodes of atrial fibrillation (AF) contribute to LA remodeling. Methods and Results: Forty‐five patients who diagnosed as LPAF and age‐, gender‐, and body mass index‐matched healthy control subjects (n = 45) were enrolled. Patients were grouped based on the frequency of AF episodes. An echocardiography was performed >2 weeks after last episode of AF without antiarrhythmic drugs. There were no statistical differences in left ventricular (LV) diastolic and systolic functions as well as baseline characteristics between patients and controls, whereas, patients had significantly larger LA volume (LAV), lower active LA emptying fraction (LAEF_active, P = 0.009) and total LAEF (LAEF_total, P = 0.005) compared with controls. Passive LAEF (LAEF_passive) was not different between patients and controls (P = 0.664). LAEF_active was significantly depressed in patients with frequent episodes of AF than the others (P = 0.034). Conclusions: Compared with healthy controls, patients with LPAF had increased LAV and depressed LAEF_active and LAEF_total without accompanying compensatory increase in LAEF_passive. LAEF_active was influenced by frequent episodes of AF. These findings may support the hypothesis that LPAF is “not‐so‐lone AF” and related to the concealed cardiac dysfunctions. (Echocardiography 2011;28:44‐51)     

Deterioration of interatrial conduction in patients with paroxysmal atrial fibrillation: Electroanatomic mapping of the right atrium and coronary sinus

OBJECTIVES: The purpose of this study was to analyze the velocities across the coronary sinus ostium (cross-CSo) and within the coronary sinus (intra-CS) in patients with and without paroxysmal atrial (AF) fibrillation and to estimate the interatrial conduction deterioration area in AF patients. BACKGROUND: Interatrial conduction delay in AF patients has been reported. However, localization of the interatrial conduction delay still is not clear. METHODS: Thirteen patients with paroxysmal AF and 10 control patients with AV nodal reentrant tachycardia or ectopic atrial tachycardia were enrolled in the study. Right atrial and CS mapping were performed using the CARTO electroanatomic mapping system during sinus rhythm and during distal CS pacing. The activation times and spatial distances of cross-CSo and intra-CS were measured between paired sites, from which the activation velocities of cross-CSo and intra-CS were obtained. RESULTS: During sinus rhythm, the activation velocities of cross-CSo in the AF group (1.2 +/- 0.2 m/s) were significantly slower than those in the control group (2.9 +/- 1.6 m/s, P < .05). During distal CS pacing, the cross-CSo velocities of the AF group (1.0 +/- 0.5 m/s) also appeared slower than those in the control group (1.4 +/- 0.2 m/s, P = .07). However, no difference was found in intra-CS activation velocities between the two groups (2.8 +/- 1.9 vs 3.2 +/- 2.2 m/s and 1.5 +/- 0.3 vs 1.4 +/- 0.3 m/s, P > .05 during sinus rhythm and distal CS pacing, respectively). CONCLUSIONS: Interatrial conduction at the posteroparaseptal region across the CS ostium was significantly slower in patients with paroxysmal AF than in control patients, further supporting the link between interatrial conduction deterioration and paroxysmal AF.     

Discrimination of left atrial and pulmonary vein potentials in patients with paroxysmal atrial fibrillation

INTRODUCTION: Ablation of muscular fascicles around the ostium of pulmonary veins (PVs) resulting in electrical isolation of the veins may prove to be an effective treatment for atrial fibrillation (AF). Correctly discriminating atrial and PV potentials is necessary to effectively isolate PVs from the left atrium in patients with paroxysmal AF. METHODS AND RESULTS: A training set of 151 electrode recordings obtained from 10 patients with AF was used to develop an algorithm to discriminate atrial and PV potentials. Bipolar electrograms were collected from a multielectrode basket catheter placed sequentially into each PV. Amplitude, slope, and normalized slopes of both bipolar and quadripolar electrograms (difference between adjacent bipoles) were entered into a binary logistic regression model. A receiver operating characteristic curve was used to define a threshold able to effectively discriminate atrial and PV potentials. The normalized slopes of both domains, bipolar and quadripolar, produced a logistic function that discriminated atrial and PV potentials against a threshold (0.38) with 97.8% sensitivity and 94.9% specificity. The algorithm then was evaluated on a test set of 214 electrode recordings from four patients who also had paroxysmal AF. These patient electrograms also were evaluated by two independent electrophysiologists. The algorithm and electrophysiologists matched identification of activation origin in 84% of electrograms. CONCLUSION: Atrial and PV potentials acquired from a multielectrode basket catheter can be discriminated using the normalized slopes of bipolar and quadripolar electrograms. These additional parameters need to be included by physicians determining the preferential ablation site within PVs.     

Electroanatomic mapping of right atrial activation in patients with and without paroxysmal atrial fibrillation

Inter-atrial conduction delay in patients with atrial fibrillation (AF) has been reported. However, the area of this conduction delay has not been well identified. The activation time and conduction velocity over the right atrial endocardium were evaluated during sinus rhythm using the CARTO mapping technique in 6 patients with paroxysmal AF (AF group) and 11 patients without history of AF (control group). No significant differences were observed between the 2 groups in the mean activation times and conduction velocities from the earliest activation site to the superior septum, His bundle area and coronary sinus ostium, or in the total activation times of the right atrium. There was no significant difference between the two groups in the local conduction velocity between 2 adjacent sites in the free wall, septum and bottom of the right atrium. This study suggests the previously reported conduction delay in the posteroseptal region in patients with paroxysmal AF might locate within the posterior inter-atrial septum.     

Left and right atrial size and the occurrence predictors in patients with paroxysmal atrial fibrillation

The purpose of the present study is to evaluate left and right atrial volume in patients with paroxysmal atrial fibrillation (PAF) and to select the best clinical variables to predict the occurrence of PAF. 157 patients and 106 normal subjects were enrolled. In patients with PAF, right atrial volume and dimension were all significantly greater (P<0.001 approximately 0.05). Left atrial (LA) volume were obviously higher (P<0.01) before correction for age. Atrial dilation and right atrial shape remoding are evident compared to normal controls. Patients are more prone to PAF occurrence if they have increased LA anterior-posterior diameter, greater P maximum and advancing age.     

心房肌易损性与阵发性心房颤动的发生机制

目的探讨左、右心房肌复极,及其易损性与阵发性心房颤动(AF)的发生与维持机制。方法应用单相动作电位(MAP)技术记录14只犬左、右心房肌的复极达90%动作电位时程(APD90),通过S1S2程序刺激,同时记录心房有效不应期(ERP)及相对不应期(RRP),观察反复心房激动(RAF,在S1S2的早搏刺激后,发生2个以上的连续心房活动,从心房刺激到RAF第一个激动的间期必须小于250 ms)及AF的诱发。结果14只犬S1S2间期递减至130±32 ms时,可出现RAF,随后当S1S2间期缩短为110±28 ms时AF发作。AF发作前大多数可记录到RAF(66.7%);共诱发出15阵RAF,左房11阵,右房4阵,左房RAF的发生率明显多于右房(P<0.05);共诱发出18阵AF,左房诱发出12阵,右房诱发出6阵。左房的AF诱发率明显多于右房(P<0.05)。结论AF发作前多伴有RAF发作;RAF是易发生阵发性AF的特征性表现,代表心房的易损性;左右心房易损性不同。     

Right atrium monophasic action potentials during atrial flutter and fibrillation in man.

Monophasic action potentials recorded in two patients with atrial flutter and one patient with atrial fibrillation showed a nonuniform depolarization of the right atrial wall. In each of the two patients with atrial flutter, there was a site where two separate action potential deflections were recorded for each flutter wave. It was supposed that this was the site of re-entry for a cycling wavelet subsidiary to the main flutter wave. In the patient with atrial fibrillation, three types of electric atrial activity were found: regular activity at 180 per minute similar to that found in flutter, small irregular activity at a rate of 400 per minute, and a mixed type of the former two. The significance of these findings for the mechanism of atrial flutter and fibrillation is discussed.     

A typical pattern of activation in the right atrium during paroxysmal atrial fibrillation: the washing-machine phenomenon

Atrial fibrillation affects a large population of patients. The electrophysiological mechanisms that initiate and maintain atrial fibrillation may be multiple. Even if some studies exploring right atrial activation have been recently published, data concerning atrial fibrillation activation patterns and its mechanisms are still scarce and controversial. This study supplies information on right atrial activation during atrial fibrillation. Twenty-four patients with recurrent, drug-refractory, lone paroxysmal atrial fibrillation underwent an extensive mapping of the right atrium. A pattern of organized atrial fibrillation (type 1) was noted in the trabeculated right atrium and atrial roof, characterized by discrete atrial electrograms, separated by an isoelectric baseline, with a continuous switching between clockwise and counterclockwise activation that we called washing-machine phenomenon. In the majority of patients, recordings from the anterior and medial areas of the atrial septum, showed fractionated electrograms consistent with a more disorganized activation pattern. Atrial activation in the inferior septum and coronary sinus was rather disorganized, neither synchronized with the activation sequence of the trabeculated right atrium nor with that of the anterior septum. Furthermore, the activation pattern showed fractionated electrograms and a variability of the isoelectric baseline similar to that recorded in the septum. No significant complications were reported during the procedure. In conclusion, mapping of the right atrium during induced atrial fibrillation shows a very typical pattern of activation in the trabeculated right atrium that we called the washing-machine phenomenon. Whether this sequence of activation represents a bystander situation or an active conditioning factor needs further investigations.