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Abstract: Background: The occurrence of eccentric retrograde atrial activation has been demonstrated to be from 6 to 8% in patients with atrioventricular nodal reentrant tachycardia (AVNRT) by several previous reports. However, most of those reports were limited by the absence of coronary sinus venography to confirm if the retrograde activation was truly left sided. The purposes of this study were to 1) determine the incidence of left sided retrograde atrial activation in our center, 2) determine the specific electrophysiologic characteristics of eccentric and concentric atrial activation and 3) determine the outcome of radiofrequency catheter ablation for AVNRT with eccentric retrograde atrial activation. Methods: From November 2001 to July 2004, 290 consecutive patients with AVNRT who underwent an electrophysiologic study and radiofrequency ablation were included. Group 1 consisted of AVNRT patients with eccentric retrograde atrial activation; group 2 consisted of AVNRT patients with concentric retrograde atrial activation. The electrophysiologic characteristics of the group 1 and group 2 patients were then compared. Results: The incidence of AVNRT with eccentric retrograde activation confirmed by CS venography was 6.5%. There were more females and atypical AVNRT in patients with retrograde eccentric conduction. There was more VA block after ablation and tachycardia induction by right ventricular pacing/extrastimuli in eccentric rather than concentric retrograde atrial activation. A shorter antegrade fast functional refractory period of the AV node was demonstrated in the atypical eccentric group as compared to the atypical concentric group. Conclusion: This study demonstrated the different electrophysiologic characteristics between the AVNRT patients with eccentric and concentric retrograde atrial activation. Successful ablation sites were similar to the standard RA ablation sites in patients with retrograde eccentric conduction. [Copyright &y& Elsevier]

Backgrounds: Radiofrequency (RF) catheter ablation represents a major advance in the management of children with cardiac arrhythmias and has rapidly become the standard of care for the first-ling therapy of supraventricular tachycardias (SVTs). The purpose of this study was to investigate the results of the RF catheter ablation of SVTs in pediatric patients. Methods: From December 1989 to August 2005, a total of 228 pediatric patients (age: 9 ± 7 years, range: 5–18 years; male:female = 117:111) with clinically documented SVT underwent an electrophysiologic study and RF catheter ablation at our institution. Results: The arrhythmias included atrioventricular reentrant tachycardia (AVRT; n = 140, 61%), atrioventricular nodal reentrant tachycardia (AVNRT; n = 66, 29%), atrial tachycardia (AT; n = 11, 5%), and atrial flutter (AFL; n = 11, 5%). The success rate of the RF catheter ablation was 92% for AVRT, 97% for AVNRT, 82% for AT, and 91% for AFL, respectively. Procedure-related complications were infrequent (8.7%; major complications: high grade AV block (2/231, 0.9%); minor complications: first degree AV block (6/231, 2.6%), reversible brachial plexus injury (2/231, 0.9%), and local hematomas or bruises (10/231, 4.3%)). The recurrence rate was 4.7% (10/212) during a follow-up period of 86 ± 38 months (0.5–185 months). Conclusions: The RF catheter ablation was a safe and effective method to manage children with paroxysmal and incessant tachycardia. The substrates of the arrhythmias differed between the pediatric and adult patients. However, the success rate of the ablation, complications, and recurrence during childhood were similar to those of adults. [ABSTRACT FROM AUTHOR]

Background: Atrioventricular nodal reentrant tachycardia (AVNRT) can usually be induced by atrial stimulation. However, it seldom may be induced with only ventricular stimulation, especially the fast-slow form of AVNRT. The purpose of this retrospective study was to investigate the specific electrophysiological characteristics in patients with the fast-slow form of AVNRT that could be induced with only ventricular stimulation. Methods: The total population consisted of 1,497 patients associated with AVNRT, and 106 (8.4%) of them had the fast-slow form of AVNRT and 1,373 (91.7%) the slow-fast form of AVNRT. In patients with the fast-slow form of AVNRT, the AVNRT could be induced with only ventricular stimulation in 16 patients, Group 1; with only atrial stimulation or both atrial and ventricular stimulation in 90 patients, Group 2; and with only atrial stimulation in 13 patients, Group 3. We also divided these patients with slow-fast form AVNRT (n = 1,373) into two groups: those that could be induced only by ventricular stimulation (Group 4; n = 45, 3%) and those that could be induced by atrial stimulation only or by both atrial and ventricular stimulation (n = 1.328, 97%). Results: Patients with the fast-slow form of AVNRT that could be induced with only ventricular stimulation had a lower incidence of an antegrade dual AVN physiology (0% vs 71.1% and 92%, P < 0.001), a lower incidence of multiple form AVNRT (31% vs 69% and 85%, P = 0.009), and a more significant retrograde functional refractory period (FRP) difference (99 ± 102 vs 30 ± 57 ms, P < 0.001) than those that could be induced with only atrial stimulation or both atrial and ventricular stimulation. The occurrence of tachycardia stimulated with only ventricular stimulation was more frequently demonstrated in patients with the fast-slow form of AVNRT than in those with the slow-fast form of AVNRT (15% vs 3%, P < 0.001). Patients with the fast-slow form of AVNRT that could be induced with only ventricular stimulation had a higher incidence of retrograde dual AVN physiology (75% vs 4%, P < 0.001), a longer pacing cycle length of retrograde 1:1 fast and slow pathway conduction (475 ± 63 ms vs 366 ± 64 ms, P < 0.001; 449 ± 138 ms vs 370 ± 85 ms, P = 0.009), a longer retrograde effective refractory period of the fast pathway (360 ± 124 ms vs 285 ± 62 ms, P = 0.003), and a longer retrograde FRP of the fast and slow pathway (428 ± 85 ms vs 362 ± 47 ms, P < 0.001 and 522 ± 106 vs 456 ± 97 ms, P = 0.026) than those with the slow-fast form of AVNRT that could be induced with only ventricular stimulation. Conclusion: This study demonstrated that patients with the fast-slow form of AVNRT that could be induced with only ventricular stimulation had a different incidence of the antegrade and retrograde dual AVN physiology and the specific electrophysiological characteristics. The mechanism of the AVNRT stimulated only with ventricular stimulation was supposed to be different in patients with the slow-fast and fast-slow forms of AVNRT. [ABSTRACT FROM AUTHOR]

Background: The majority of cardiac arrhythmias in children are supraventricular tachycardia, which is mainly related to an accessory pathway (AP)-mediated reentry mechanism. The investigation for Wolff-Parkinson-White (WPW) syndrome in adults is numerous, but there is only limited information for children. This study was designed to evaluate the specific electrophysiologic characteristics and the outcome of radiofrequency (RF) catheter ablation in children with WPW syndrome. Methods: From December 1989 to August 2005, a total of 142 children and 1,219 adults with atrioventricular reentrant tachycardia (AVRT) who underwent ablation at our institution were included. We compared the clinical and electrophysiologic characteristics between children and adults with WPW syndrome. Results: The incidence of intermittent WPW syndrome was higher in children (7% vs 3%, P= 0.025). There was a higher occurrence of rapid atrial pacing needed to induce tachycardia in children (67% vs 53%, P= 0.02). However, atrial fibrillation (AF) occurred more commonly in adult patients (28% vs 16%, P = 0.003). The pediatric patients had a higher incidence of multiple pathways (5% vs 1%, P < 0.001). Both the onset and duration of symptoms were significantly shorter in the pediatric patients. The antegrade 1:1 AP conduction pacing cycle length (CL) and antegrade AP effective refractory period (ERP) in children were much shorter than those in adults with manifest WPW syndrome. Furthermore, the retrograde 1:1 AP conduction pacing CL and retrograde AP ERP in children were also shorter than those in adults. The antegrade 1:1 atrioventricular (AV) node conduction pacing CL, AV nodal ERP, and the CL of the tachycardia were all shorter in the pediatric patients. Conclusion: This study demonstrated the difference in the electrophysiologic characteristics of APs and the AV node between pediatric and adult patients. RF catheter ablation was a safe and effective method to manage children with WPW syndrome. [ABSTRACT FROM AUTHOR]

Right Atrial Substrate of Supraventricular Tachyarrhythmias. Background:Voltage mapping has been used to detect diseased myocardium. However, accurate determination of the local atrial voltage at the same site, and simultaneous recordings from multiple mapping sites were limited. The purpose of this study was to investigate the right atrial (RA) substrate properties in patients with supraventricular tachyarrhythmias (SVT).Methods and Results:Forty patients (aged 55± 20 years) undergoing noncontact mapping and ablation of SVT constituted the study population. There were eight patients with atrioventricular node reentrant tachycardia (AVNRT), eight patients with focal atrial tachycardia (AT), 14 patients with atrial flutter (AFL), and 10 patients with atrial fibrillation (AF). The mean peak negative voltage (PNV) was analyzed in virtual unipolar electrograms, which were obtained from 256 equally distributed RA endocardial sites during sinus rhythm (SR), atrial pacing, and tachycardia. The mean PNV of global RA during SR (−1.34± 0.22 vs.−0.90± 0.40 vs.−1.00± 0.36 vs.−0.85± 0.35 mV, P= 0.04), atrial pacing at cycle lengths of 500 ms (−1.30± 0.29 vs.−0.70± 0.35 vs.−0.76± 0.25 vs.−0.64± 0.26 mV, P= 0.02), and 300 ms (−1.54± 0.47 vs.−0.94± 0.21 vs.−0.75± 0.27 vs.−0.57± 0.22 mV, P<0.01) were significantly greater in patients with AVNRT compared to AT, AFL, and AF. Furthermore, the mean PNV decreased during atrial pacing with shorter pacing cycle length was demonstrated only in patients with AFL and AF.Conclusion:Negative unipolar voltage analysis of global RA showed different RA substrate characteristics during various SVT. The substrate property of activation and cycle length-dependent voltage reduction may be related to the development of AFL and AF.(J Cardiovasc Electrophysiol, Vol. 16, pp. 1-8, March 2005) [ABSTRACT FROM AUTHOR]

Focal Atrial Tachycardia. Introduction:Adenosine can terminate most focal atrial tachycardias (ATs). However, information about the termination mechanism is limited. This study investigated the effects and mechanism of adenosine on terminating focal AT using a three-dimensional noncontact mapping system.Methods and Results:The study consisted of 7 patients (4 men and 3 women; age 44± 29 years) with focal AT. Cycle length variation and atrial activation pattern at baseline and just before AT termination by adenosine (3–12mg) were analyzed. Noncontact mapping demonstrated focal AT propagated from the origin (O) with preferential conduction and spread away from the breakout sites to the whole atrium. Compared to baseline AT, termination episodes revealed higher mean beat-to-beat variation of AT cycle length (11.7± 11.7 msec vs 4.7± 4.5 msec, P<0.001) and standard deviation of normalized AT cycle length (0.033± 0.014 vs 0.011± 0.005, P<0.001). In termination episodes, adenosine significantly decreased the peak negative voltage of AT-O (–27.2± 15.3%, P<0.01), preferential conduction (proximal:–32.1± 18.7, mid:–28.4± 22.8, distal portion:–29.6± 21.4%, P<0.01), and breakout (–31.4± 12.5%, P<0.01). However, adenosine did not affect voltage in nontermination episodes. Adenosine shifted the locations of AT-O in 5 of 10 AT episodes with termination. Mean number of shifting AT-O was 2.4± 1.5 (range 1–4), with maximum shifting distance of 15.0± 3.1 (range 10–19) mm. Focal activation at AT-O simply disappeared in all termination episodes and therefore was not due to conduction block within preferential conduction or breakout site. Catheter ablation lesions covered 50% of total shifting origins, without late recurrence.Conclusion:Adenosine-induced AT termination was associated with significantly decreased electrogram voltage, shifting AT-O locations, and disappearance of focal activation.(J Cardiovasc Electrophysiol, Vol. 15, pp. 1-7, December 2004) [ABSTRACT FROM AUTHOR]

LIN, Y.-J.,et al.: Electrophysiological Mechanisms and Catheter Ablation of Complex Atrial Arrhythmias from Crista Terminalis: Insight from Three-Dimensional Noncontact Mapping. Paroxysmal atrial fibrillation (PAF) can be initiated by ectopic activation from the crista terminalis. The crista terminalis conduction gap is also a critical isthmus in atrial reentrant arrhythmias like upper and lower loop reentry. The aim of this study was to investigate the mechanism and results of catheter ablation for complex atrial arrhythmias originating from the crista terminalis using the noncontact mapping system (NCM). The study population consisted of six patients (5 men, 1 woman; 70± 9 years) with drug refractory PAF and typical/atypical atrial flutter. NCM identified the earliest ectopic activation originating from the crista terminalis in these six patients. The reentry circuit of atypical atrial flutter propagated around the upper crista terminalis in five patients, and lower crista terminalis in one patient. The reentry circuit of atypical atrial flutter and the initial reentry circuit of AF conducted through the crista terminalis gap in all patients. Radiofrequency applications were delivered on the sites of ectopy, which initiated AF. Substrate modification was also performed over the crista terminalis gap (six patients) and cavotricuspid isthmus (three patients) responsible for the reentry. During a mean follow-up of 9± 5 months (range 5–18 months), five patients were free of AF without antiarrhythmic drugs, and one patient did not have AF or atrial flutter using propafenone. NCM demonstrated the mechanism of crista terminalis ectopy-initiating AF and associated typical/atypical atrial flutter. Catheter ablation of crista terminalis ectopy and substrate for the reentry guided by NCM successfully eliminated these atrial arrhythmias.(PACE 2004; 27:1231–1239) [ABSTRACT FROM AUTHOR]

Noncontact Mapping of Typical Atrial Flutter. Introduction: The aim of this study was to delineate activation patterns around the crista terminalis (CT) using high-resolution noncontact mapping. Methods and Results: Twenty-six patients with typical atrial flutter (20 counterclockwise and 6 clockwise) were enrolled in the study. A noncontact mapping system was used to map atrial flutter. There were three activation patterns around the line(s) of block. Type I (n = 6) showed activation around a single complete line of block located in the CT. Type II (n = 17) showed activation around a single incomplete line of block with a conduction gap in the CT. Type III (n = 3) showed activation around double lines of block, one located in the CT and the other located in the sinus venosa region. Simultaneous activation around the tricuspid annulus and through the CT gap could result in double loop reentry (n = 12). After successful ablation of the cavotricuspid isthmus (CTI) in 24 patients, upper loop reentry was still induced in 12 patients with double loop reentry. Subsequent ablation of the CT gap was performed successfully in these 12 patients, and no arrhythmia was inducible thereafter. During the follow-up period of 8.4 ± 4.1 months, there was no recurrence of atrial flutter in any patient. Conclusion: During typical atrial flutter, the CT might be an incomplete barrier. Simultaneous conduction through the CTI and CT gap could result in double loop reentry. Radiofrequency ablation of the CTI and CT gap was effective in eliminating this arrhythmia. (J Cardiovasc Electrophysiol, Vol. 15, pp. 406-414, April 2004) [ABSTRACT FROM AUTHOR]

Presents the case of a 15-year-old man with a supraventricular tachycardia with changing morphology of QRS complex and tachycardia cycle length induced by ventricular burst pacing. Medical history of the patient; Possible mechanism explaining supraventricular tachycardias with progressive change of QRS complex morphology; Reason for the progressive preexcitation of the QRS complex.

Gender differences of supraventricular tachycardias such as atrioventricular nodal re-entry, atrioventricular re-entry, and atrial fibrillation have been reported. There is little evidence of the effect of gender on focal atrial tachycardia (FAT). The study consisted of 298 patients who were referred to this institution for radiofrequency catheter ablation of FAT from October 1992 to April 2008 and included 156 men (52%) and 142 women (48%). Men were significantly older than women (57.9 ± 18.2 vs 47.2 ± 19.0 years old, p <0.001). Women had more associated arrhythmias (17.0% vs 28.9%, p = 0.01), mostly due to an increased incidence of atrioventricular nodal re-entrant tachycardia. Men had more cardiovascular co-morbidities (19.9% vs 9.9%, p = 0.02), a mechanism of increased automaticity (19.1% vs 8.1%, p = 0.01), and nonparoxysmal tachycardia (14.7% vs 4.4%, p = 0.01). No gender differences were noted among FAT number, left atrial involvement, shortest tachycardia cycle, success rate of catheter ablation, or recurrence rate of FAT. Mean duration of follow-up was 63.2 ± 47.5 months. Premenopausal women had a lesser cardiovascular co-morbidity (15.3% vs 4.3%, p = 0.04) and a greater incidence of a mechanism of increased automaticity (13.4% vs 2.9%, p = 0.03). In conclusion, gender differences in electrophysiologic characteristics were noted in FAT. [Copyright &y& Elsevier]

Abstract: Background: The significant role of bundle branch block during atrioventricular nodal reentrant tachycardia (AVNRT) is not clear. The purposes of this study were to study the effects of complete right bundle branch block (RBBB) on electrophysiological parameters during AVNRT and to define the significance of complete RBBB during AVNRT. Methods and results: According to characteristics of electrocardiogram during sinus rhythm and AVNRT, 50 patients who underwent catheter ablation for slow¿fast AVNRT were divided into three groups. Group I included 20 patients who had narrow QRS (¿110 ms) during sinus rhythm and AVNRT. Group II included 18 patients who had persistent RBBB (¿120 ms) during sinus rhythm and AVNRT. Group III included 12 patients who had narrow QRS during sinus rhythm, but they had narrow QRS and transient RBBB during AVNRT. The atrio-His (AH) interval (296±60 vs. 288±75 ms), His-ventricular (HV) interval (36±11 vs. 35±11 ms), His-atrial (HA) interval (72±24 vs. 71±28 ms), VAHRA interval (defined as the interval between the onset of ventricular depolarization and the onset of atrial activity of right high atrium; 34±24 vs. 37±25 ms), VACSO interval (defined as the interval between the onset of ventricular depolarization and the onset of atrial activity of coronary sinus ostium; 13±28 vs. 26±23 ms) and tachycardia cycle length (TCL; 368±67 vs. 359±73 ms) during AVNRT were similar between group I and group II (all P>0.05). In group III, the AH interval (255±81 vs. 246±83 ms), HV interval (44±5 vs. 42±11 ms), HA interval (66±19 vs. 70±15 ms), VAHRA interval (27±15 vs. 29±16 ms), VACSO interval (23±25 vs. 21±25 ms) and TCL (322±76 vs. 316±77 ms) were not significantly different between AVNRT with narrow QRS and those with transient RBBB (all P>0.05). Conclusions: Persistent RBBB and transient RBBB have no significant effects on the electrophysiological parameters during AVNRT. These findings suggest that RBBB might not influence the conduction of lower common pathway or the circuit of AVNRT. [Copyright &y& Elsevier]