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Can successful radiofrequency ablation of atrioventricular nodal reentrant tachycardia be predicted by pattern of junctional ectopy?
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Journal of Electrocardiology 41 (2008) 39 – 43 www.jecgonline.com
Can successful radiofrequency ablation of atrioventricular nodal reentrant tachycardia be predicted by pattern of junctional ectopy? Mohammad Hossein Nikoo, MD, Zahra Emkanjoo, MD, ⁎ Mohammad Vahid Jorat, MD, Ali Kharazi, MD, Abolfath Alizadeh, MD, Amir Farjam Fazelifar, Mohammad Ali Sadr-Ameli Department of Pacemaker and Electrophysiology, Rajaie Cardiovascular Research and Medical Center, Tehran, Iran Received 17 March 2007
Abstract
Background: Emergence of junctional rhythm (JR) during radiofrequency (RF) current delivery directed at the periatrioventricular nodal region has been shown to be a marker of success in atrioventricular nodal reentrant tachycardia (AVNRT). Whereas the characteristics of JR during RF ablation of slow pathway have already been studied, the electrophysiologic features of different patterns of JR are yet to be evaluated. The aim of this study was to investigate in detail the characteristics of the JR that develops during the RF ablation of the slow pathway. Materials and Results: The study population consisted of 95 patients: 56 women and 33 men (mean age, 47.2 ± 16.3 years) who underwent slow pathway ablation because of AVNRT. A combined anatomical and electrogram mapping approach was used, and AVNRT was successfully eliminated in all patients. This study identified 7 patterns for JR during the RF ablation of slow pathway: junctionjunction-junction, sinus-junction-sinus, intermittent burst, sparse, no junction, sinus-junctionjunction, and sinus-junction-block . The characteristics of JR, such as mean cycle length and total number, were gathered. The incidence of JR was significantly higher during effective applications of RF energy than during ineffective applications (P = .001). The mean number of junctional ectopy was 19.6 ± 19. The total number of junctional ectopy was significantly higher during effective applications of RF energy than during ineffective applications (24.6 ± 18.8 vs 8.4 ± 13.2; P b .001). We found a significant difference between the effective and ineffective applications of RF energy in the mean cycle length of the junctional ectopy (464.6 ± 167.5 vs 263.4 ± 250.2; P b .01). The patterns of JR were compared between effective and ineffective applications. We managed to show a significant correlation between patterns of JR and successful ablation (P = .01). Logistic regression analysis revealed that the presence of sinus-junction-sinus, sinus-junctionjunction, and sinus-junction-block patterns of JR was a predictor of a successful RF ablation (confidence interval [CI], 1.67-15.92 [P b .004]; CI, 1.02-85.62 [P = .048]; and CI, 1.06-32.02 [P = .042], respectively). Conclusion: This study confirms that JR is often present during successful slow pathway ablation. The pattern of JR is useful as indicator of success. © 2008 Elsevier Inc. All rights reserved.
Keywords:
Junctional ectopy; Slow pathway; AVNRT; RF ablation
Introduction Catheter-based slow pathway modification has become a first−line treatment of recurrent atrioventricular nodal
⁎ Corresponding author. Tel.: +98 212391; fax: +98 2122055594. E-mail address: [email protected] 0022-0736/$ – see front matter © 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.jelectrocard.2007.07.005
reentrant tachycardia (AVNRT) with success rates approaching 100%.1,2 Emergence of junctional rhythm (JR) during radiofrequency (RF) current delivery directed at the periatrioventricular (AV) nodal region has been shown to be a marker of successful catheter ablation in AVNRT and has been considered as a response of the AV node to the thermal injury of either the nodal or the perinodal tissue.3-6
40
M.H. Nikoo et al. / Journal of Electrocardiology 41 (2008) 39–43
The characteristics of accelerated JR (AJR) during RF ablation of slow pathway have been studied in association with the outcome of catheter ablation.7 However, the electrophysiologic features of different patterns of JR have not yet been evaluated. This study sought to investigate in detail the electrophysiologic characteristics of JR that develops after RF ablation of the slow pathway and to determine their significance in predicting the successful RF ablation.
Materials and methods The study population comprised 95 patients: 56 women and 33 men (mean age, 47.2 ± 16.3 years; range, 1881 years) who underwent slow pathway ablation because of AVNRT between October 2005 and June 2006 in our center. We excluded 6 patients with more than 5 applications of RF energy from this study because the cumulative effect of burns might be a confounding factor. These patients received a total of 127 RF energy applications. There were 3 patients with coronary artery disease and 2 patients with valvular heart disease; the remainder had no structural heart disease. Electrophysiology considerations All the patients gave their informed consent, and electrophysiologic tests were done under local anesthesia in fasting state. Three 6F quadripolar electrode catheters were introduced percutaneously into the femoral veins and positioned at the high right atrium, His-bundle region, and right ventricular apex; and a 7F steerable decapolar catheter was placed in the coronary sinus from the right femoral vein or subclavian vein. Mapping and RF ablation were performed using a steerable 7F quadripolar catheter with a 4-mm tip and 2-mm interelectrode spacing (Ablatr or Mariner, Medtronic Inc, Minneapolis, MN). Radiofrequency current was delivered by a 500-KHz generator (Attakr II, Medtronic Inc) at a constant preset electrical power (30-50 W) between the distal electrode and a large patch electrode on the posterior thorax as the indifferent electrode. A preset target temperature of 50°C to 70°C was programmed. Concomitant recording of leads I, II, III, and V1, in addition to the said intracardiac recordings, were used. Incremental pacing and programmed stimulation were performed in the right atrium and right ventricle to define antegrade and retrograde AV nodal conduction and refractoriness. In 4 patients, the induction of AVNRT required the infusion of isoproterenol. When isoproterenol was required to induce AVNRT, RF energy delivery was delayed until the effects of isoproterenol had dissipated and sinus rate had returned to baseline. There were 79 patients with slow-fast typical AVNRT, 2 patients with both slow-fast and fast-slow AVNRT, and 1 patient with left variant slow-fast type. The mean of AV Wenckebach point was 323.98 ± 68 milliseconds with a range from 210 to 575. The mean of ventriculoatrial Wenckebach point was 323.3 ± 57 milliseconds with a range from 200 to 530, that of antegrade effective refractory
period of slow pathway was 244 ± 45 milliseconds, and that of fast pathway was 313 ± 54 milliseconds. Anatomical area between the His catheter and the coronary sinus ostium in the left oblique anterior projection was divided into 5 areas: low posteroseptal, high posteroseptal, low midseptal, high midseptal, and anteroseptal. The suitable site for ablation was identified according to electeroanatomical mapping by multicomponent A wave and A/V ratio of less than 0.5. RF energy was applied with 50 W energy and 60°C temperatures. All the burns that lasted for more than 15 seconds were included; and after each RF energy application, the inducibility of AVNRT was reexamined with the same protocol, which was used for induction. If AVNRT was noninducible, isoproterenol infusion was started and inducibility was rechecked. In some cases, after applying a few RF energy (b15 seconds) using electeroanatomical approach at the site of recorded slow pathway potential if no JR was observed, programmed stimulation was performed to reassess the inducibility of the AVNRT. If tachycardia was not inducible, RF energy was applied for 60 seconds despite the absence of JR. Success was agreed only if AVNRT was noninducible after isoproterenol infusion. Residual slow pathway conduction, demonstrated as a single AV nodal echo, was present in 65 patients. In the remaining 24 patients, there was no evidence of residual slow pathway activity. After each RF application, the patterns of JR were analyzed according to the following definitions: (1) JJJ (junction-junction-junction) pattern: JR span is more than 95% of total time of each application of RF energy and lasts more than 15 seconds. It could even persist after interruption of RF application. (2) SJS (sinus-junction-sinus) pattern: JR appears after at least 5 sinus beats and persists during RF energy delivery. It is terminated by more than 5 sinus beats before the cessation of RF application. (3) SJJ (sinus-junction-junction) pattern: JR appears after more than 5 sinus beats and persists up to cessation of the RF application. (4) Intermittent burst: individual bursts of JR (at least 5 beats in each burst) with more than 5 sinus beats between bursts that intermittently appear during RF energy delivery. (5) Sparse: the junctional ectopy appears in a sparse pattern (N5 ectopies during each burst). (6) No junction: absence of JR during RF energy delivery. (7) SJB (Sinus Junction Block) pattern: the RF energy delivery interrupted after the appearance of ventriculoatrial block or AV block during JR. Statistical analysis Data were analyzed with Statistical Package for the Social Sciences (SPSS, Chicago, IL) software (version 13) using conventional methods for mean and SDs and nonparametric tests to evaluate group differences. Univariate and
M.H. Nikoo et al. / Journal of Electrocardiology 41 (2008) 39–43
multivariate analyses with a stepwise logistic regression model were performed to analyze variables that could predict the success of RF ablation. A P value of less than .05 was considered significant. Results All the patients had a successful outcome of noninducibility of AVNRT. The mean number of RF applications was 1.43 ± 0.6, and the cumulative energy was 3757 ± 0.6 J. The incidence and characteristics of the JR are shown in Table 1. Junctional rhythm appeared during 82 (94.25%) of 87 effective applications of RF energy and in 26 (65%) of 40 ineffective applications. The incidence of JR was significantly higher during effective application of RF energy than during ineffective application (P = .001). The mean number of junctional ectopy was 19.6 ± 18.8 (range, 75). The mean cycle length of the JR was 405.5 ± 215.1. The total number of junctional ectopy was significantly higher during effective applications of RF energy than during ineffective applications (24.6 ± 18.8 vs 8.4 ± 13.1; P b .001). We found that the number of junctional ectopy (N20) was significantly associated with the successful RF ablation (P b .001). We also found a significant difference between the effective and ineffective applications of RF energy in the mean cycle length of the JR (464.6 ± 167.5 vs 263.4 ± 250.2; P b .01). The patterns of JR were assessed and compared between effective and ineffective RF applications. Incidence of different patterns of JR is shown in Table 2. We succeeded in showing a significant correlation between junctional patterns and successful ablation (P = .01). Logistic regression analysis revealed that the presence of SJS, SJJ, and SJB patterns of JR were a predictor of a successful RF ablation (confidence interval [CI], 1.67-15.92 [P b .004]; CI, 1.02-85.62 [P = .048]; and CI, 1.06-32.02 [P = .042], respectively) (Fig. 1). Of 127 RF applications, we identified 23 burns that caused block in antegrade or retrograde conductions, of which 11 were antegrade and 10 were retrograde; 2 patients had both types. All of those blocks were transient, none of them lasting more than a few seconds. Mean temperatures and total applied energy were similar between the different patterns of JR (P = .26 and P = .8, respectively). Over a follow-up period of 9 months, AVNRT recurred in 1 patient. Table 1 Incidence and characteristics of junctional ectopy during RF ablation of slow pathway in patients undergoing RF ablation of slow pathway Effective applications
Ineffective applications
P
Total no. of junctional ectopy 24.65 ± 18.78 8.38 ± 13.16 b.001 Cycle length of junctional 464.64 ± 167.54 263.43 ± 250.24 b.01 ectopy (ms) Values are expressed as mean ± SD.
41
Table 2 Incidence of different junctional ectopy patterns during applications of RF energy in patients undergoing slow pathway ablation
Sparse SJS No junction SJB SJJ Intermittent burst JJJ
Effective applications
Ineffective applications
Total
n
n
n (%)
27 30 5 10 8 7 1
14 6 14 2 1 0 1
41 (32.5) 36 (28.3) 19 (15.0) 12 (9.4) 9 (7.1) 7 (5.5) 2 (1.6)
Most of the target sites at which junctional ectopy occurred was at high posteroseptal (62%) (Fig. 2). There was also no correlation between delivery sites and total RF energy applied and junctional patterns (P = .87 and P = .69, respectively). Discussion Main findings The characteristics of junctional ectopy during RF ablation of slow pathway have already been evaluated in association with the outcome of catheter ablation and inadvertent development of an AV conduction disturbances.7 However, no previous studies have so far compared the patterns of junctional ectopy occurring during effective applications of RF energy in patients undergoing slow pathway ablation. In the present study, we managed to show that successful ablation could be predicted by patterns of JR. We believed that such a detailed analysis might allow us to propose an additional marker of successful ablation. Applications of RF energy successful in eliminating AVNRT were associated with junctional ectopy characterized by different patterns of SJS, SJJ, and SJB, as described above. Therefore, quantization and quantification of the junctional ectopy proved useful in predicting the success of RF ablation. The area of posterior input into the AV node is complex, and the slow pathways may differ in different patients undergoing RF ablation of AVNRT, which could explain the different patterns of JR emerging during RF ablation. Characteristics of junctional ectopy associated with successful radiofrequency ablation As reported in previous studies,8,9 junctional ectopy was found to be a sensitive but nonspecific marker of successful ablation. Mcgavigan et al10 demonstrated that successful ablation of slow pathway seldom occurs in the absence of JR. Although JR almost invariably occurs with successful ablation, its lack of specificity and low positive predictive value questions its use as an end point. The occurrence of junctional ectopy during 64% of ineffective applications of RF energy in our series indicates that junctional ectopy is nonspecific marker of successful slow pathway ablation. Lee et al11 showed that there were different characteristics
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M.H. Nikoo et al. / Journal of Electrocardiology 41 (2008) 39–43
Fig. 1. Example of SJJ pattern of junctional ectopy during RF ablation of slow pathway. Tracings are surface electrocardiogram leads I, III, and V1 and intracardiac recordings from the ablation catheter. HRA indicates high right atrium; HBP, proximal His bundle; HBD, distal His bundle; RVA, right ventricular apex; CS, coronary sinus.
of the JR during slow pathway ablation of different types of AVNRT. Jentzer et al12 demonstrated that the quantification of junctional ectopy that occurs during delivery of RF energy are unlikely to be clinically useful in predicting whether a particular application was effective in eliminating the inducibility of AVNRT. In their study, there was no difference in the mean cycle length of the junctional ectopy occurring during effective and ineffective applications of RF energy, and although the bursts of junctional ectopy were significantly longer at the effective sites, the difference was relatively small in absolute terms. They reported a greater total number of junctional beats during the applications. In contrast with this study, we found a significant difference between the effective and ineffective applications of RF energy in the mean cycle length of the junctional ectopy (464.64 ± 167.54 vs 263.43 ± 250.24; P b .01). Wagshal et al,13 in their study, compared different patterns of AJR. They concluded that the much longer cycle length of the AJR associated with slow pathway ablation (604 ± 150 milliseconds) would argue against far-field activation of the compact AV node as the source of AJR. Lakobishvili et al14 found that the amount and duration of AJR is correlated with the total abolishment of slow pathway conduction. They presumed that a higher amount and duration of AJR might be an additional marker of successful ablation. Our study confirmed this finding about a greater number of junctional beats during effective RF applications. We also demonstrated that the number of junctional
ectopy (N20) is significantly associated with the successful ablation (P b .001). Poret et al15 demonstrated that midseptal ablation site is associated with a higher rate of AJR than posterior ablation site, suggesting that its origin is located close to the AV node. In our study, most of the target sites at which RF energies were applied and junctional ectopy appeared were located at
Fig. 2. Radiographic localization of catheter ablation at high posteroseptal area (P2). RA indicates right atrium; RV, right ventricle; RAO, right anterior oblique view.
M.H. Nikoo et al. / Journal of Electrocardiology 41 (2008) 39–43
the high posteroseptal area, but there was no association between the target sites of RF energy delivery and the patterns of junctional ectopy. Therefore, the pattern of junctional ectopy was not a site-dependent phenomenon. The pattern of “no junction” was observed in 15% (n = 19); but successful slow pathway ablation was possible in the absence of JR only in 5 cases. In these patients, a previous application had been associated with junctional beats. In our study, we excluded the patients with more than 5 RF deliveries, but the influence of previous RF deliveries could not be eradicated completely and it is a limitation of this study. In summary, this study confirms that JR is often present during a successful slow pathway ablation. There are distinct patterns of AJR as an indicator of a successful ablation. It could be helpful especially in patients in whom postablation study is difficult such as in patients without demonstrable dual AV nodal physiology or inducible tachycardia. References 1. Calkins H, Young P, Miller JM, et al. Catheter ablation of accessory pathway, atrioventricular nodal re-entrant tachycardia, and the atrioventricular junction: final results of a prospective, multicenter clinical trial. Circulation 1999;99:262. 2. Clague JR, Dagre N, Kottkamp H, et al. Targeting the slow pathway for atrioventricular nodal re-entrant tachycardia: initial results and long term follow-up in 379 patients. Eur Heart J 2001;22:82. 3. Wathen M, Natale A, Wolfe K, Yee R, Newman D, Klein G. An anatomically guided approach to atrioventricular node slow pathway ablation. Am J Cardiol 1992;70:886. 4. Thibault B, de Bakker JMT, Hocini M, Loh P, Wittkampf FHM, Janse MJ. Origin of heat-induced accelerated junctional rhythm. J Cardiovasc Electrophysiol 1998;9:631.
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5. Kelly PA, Mann DE, Alder SW, Fuenzalida CE, Bailey WM, Ritter MJ. Predictors of successful radiofrequency ablation of extranodal slow pathways. PACE 1994;17:1143. 6. Yu JCL, Lauer MR, Young C, Liem LB, Hou C, Sung RJ. Localization of the origin of the atrioventricular junctional rhythm induced during selective ablation of slow pathway conduction in patients with atrioventricular node re-entrant tachycardia. Am Heart J 1996;131:937. 7. Thakur RK, Klein GJ, Yee R, Stites HW. Junctional tachycardia: a useful marker during radiofrequency ablation for atrioventricular node reentrant tachycardia. J Am Coll Cardiol 1994;22:1706. 8. Jackman WM, Beckman KJ, McClelland JH, et al. Treatment of supraventricular tachycardia due to atrioventricular nodal reentry by radiofrequency catheter ablation of slow pathway conduction. N Engl J Med 1992;327:313. 9. Kay GN, Epstein AE, Dailey SM, Plumb VJ. Selective radiofrequency ablation of the slow pathway for the treatment of atrioventricular nodal reentrant tachycardia: evidence for involvement of perinodal myocardium within the reentrant circuit. Circulation 1992;85:1675. 10. Mcgavigan AD, Rae AP, Cobbe SM, Rankin AC. Junctional rhythm—a suitable surrogate endpoint in catheter ablation of atrioventricular nodal reentry tachycardia? PACE 2005;28:1052. 11. Lee SH, Tai CT, Lee PC, et al. Electrophysiological characteristics of junctional rhythm during ablation of slow pathway in different types of atrioventricular nodal reentrant tachycardia. PACE 2005;28:111. 12. Jentzer JH, Goyal R, Williamson BD, Man C, Niebauer M, Daoud E. Analysis of junctional ectopy during radiofrequency ablation of the slow pathway in patients with atrioventricular nodal tachycardia. Circulation 1994;90:2820. 13. Wagshal AB, Crystal E, Katz A. Patterns of accelerated junctional rhythm during slow pathway catheter ablation for atrioventricular nodal re-entrant tachycardia: temperature dependence, prognostic value, and insights into the nature of the slow pathway. J Cardiovasc Electrophysiol 2000;11:244. 14. Lakobishvili Z, Kusniec J, Shohat-Zabarsky R, Mazur A, Battler A, Starsberg B. Europace 2006;6:588. 15. Poret P, Leclercq C, Gras D, et al. Junctional rhythm during slow pathway radiofrequency ablation in patients with atrioventricular nodal re-entrant tachycardia. J Cardiovasc Electrophysiol 2000;11:405.
Journal of Electrocardiology 41 (2008) 39 – 43 www.jecgonline.com
Can successful radiofrequency ablation of atrioventricular nodal reentrant tachycardia be predicted by pattern of junctional ectopy? Mohammad Hossein Nikoo, MD, Zahra Emkanjoo, MD, ⁎ Mohammad Vahid Jorat, MD, Ali Kharazi, MD, Abolfath Alizadeh, MD, Amir Farjam Fazelifar, Mohammad Ali Sadr-Ameli Department of Pacemaker and Electrophysiology, Rajaie Cardiovascular Research and Medical Center, Tehran, Iran Received 17 March 2007
Abstract
Background: Emergence of junctional rhythm (JR) during radiofrequency (RF) current delivery directed at the periatrioventricular nodal region has been shown to be a marker of success in atrioventricular nodal reentrant tachycardia (AVNRT). Whereas the characteristics of JR during RF ablation of slow pathway have already been studied, the electrophysiologic features of different patterns of JR are yet to be evaluated. The aim of this study was to investigate in detail the characteristics of the JR that develops during the RF ablation of the slow pathway. Materials and Results: The study population consisted of 95 patients: 56 women and 33 men (mean age, 47.2 ± 16.3 years) who underwent slow pathway ablation because of AVNRT. A combined anatomical and electrogram mapping approach was used, and AVNRT was successfully eliminated in all patients. This study identified 7 patterns for JR during the RF ablation of slow pathway: junctionjunction-junction, sinus-junction-sinus, intermittent burst, sparse, no junction, sinus-junctionjunction, and sinus-junction-block . The characteristics of JR, such as mean cycle length and total number, were gathered. The incidence of JR was significantly higher during effective applications of RF energy than during ineffective applications (P = .001). The mean number of junctional ectopy was 19.6 ± 19. The total number of junctional ectopy was significantly higher during effective applications of RF energy than during ineffective applications (24.6 ± 18.8 vs 8.4 ± 13.2; P b .001). We found a significant difference between the effective and ineffective applications of RF energy in the mean cycle length of the junctional ectopy (464.6 ± 167.5 vs 263.4 ± 250.2; P b .01). The patterns of JR were compared between effective and ineffective applications. We managed to show a significant correlation between patterns of JR and successful ablation (P = .01). Logistic regression analysis revealed that the presence of sinus-junction-sinus, sinus-junctionjunction, and sinus-junction-block patterns of JR was a predictor of a successful RF ablation (confidence interval [CI], 1.67-15.92 [P b .004]; CI, 1.02-85.62 [P = .048]; and CI, 1.06-32.02 [P = .042], respectively). Conclusion: This study confirms that JR is often present during successful slow pathway ablation. The pattern of JR is useful as indicator of success. © 2008 Elsevier Inc. All rights reserved.
Keywords:
Junctional ectopy; Slow pathway; AVNRT; RF ablation
Introduction Catheter-based slow pathway modification has become a first−line treatment of recurrent atrioventricular nodal
⁎ Corresponding author. Tel.: +98 212391; fax: +98 2122055594. E-mail address: [email protected] 0022-0736/$ – see front matter © 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.jelectrocard.2007.07.005
reentrant tachycardia (AVNRT) with success rates approaching 100%.1,2 Emergence of junctional rhythm (JR) during radiofrequency (RF) current delivery directed at the periatrioventricular (AV) nodal region has been shown to be a marker of successful catheter ablation in AVNRT and has been considered as a response of the AV node to the thermal injury of either the nodal or the perinodal tissue.3-6
40
M.H. Nikoo et al. / Journal of Electrocardiology 41 (2008) 39–43
The characteristics of accelerated JR (AJR) during RF ablation of slow pathway have been studied in association with the outcome of catheter ablation.7 However, the electrophysiologic features of different patterns of JR have not yet been evaluated. This study sought to investigate in detail the electrophysiologic characteristics of JR that develops after RF ablation of the slow pathway and to determine their significance in predicting the successful RF ablation.
Materials and methods The study population comprised 95 patients: 56 women and 33 men (mean age, 47.2 ± 16.3 years; range, 1881 years) who underwent slow pathway ablation because of AVNRT between October 2005 and June 2006 in our center. We excluded 6 patients with more than 5 applications of RF energy from this study because the cumulative effect of burns might be a confounding factor. These patients received a total of 127 RF energy applications. There were 3 patients with coronary artery disease and 2 patients with valvular heart disease; the remainder had no structural heart disease. Electrophysiology considerations All the patients gave their informed consent, and electrophysiologic tests were done under local anesthesia in fasting state. Three 6F quadripolar electrode catheters were introduced percutaneously into the femoral veins and positioned at the high right atrium, His-bundle region, and right ventricular apex; and a 7F steerable decapolar catheter was placed in the coronary sinus from the right femoral vein or subclavian vein. Mapping and RF ablation were performed using a steerable 7F quadripolar catheter with a 4-mm tip and 2-mm interelectrode spacing (Ablatr or Mariner, Medtronic Inc, Minneapolis, MN). Radiofrequency current was delivered by a 500-KHz generator (Attakr II, Medtronic Inc) at a constant preset electrical power (30-50 W) between the distal electrode and a large patch electrode on the posterior thorax as the indifferent electrode. A preset target temperature of 50°C to 70°C was programmed. Concomitant recording of leads I, II, III, and V1, in addition to the said intracardiac recordings, were used. Incremental pacing and programmed stimulation were performed in the right atrium and right ventricle to define antegrade and retrograde AV nodal conduction and refractoriness. In 4 patients, the induction of AVNRT required the infusion of isoproterenol. When isoproterenol was required to induce AVNRT, RF energy delivery was delayed until the effects of isoproterenol had dissipated and sinus rate had returned to baseline. There were 79 patients with slow-fast typical AVNRT, 2 patients with both slow-fast and fast-slow AVNRT, and 1 patient with left variant slow-fast type. The mean of AV Wenckebach point was 323.98 ± 68 milliseconds with a range from 210 to 575. The mean of ventriculoatrial Wenckebach point was 323.3 ± 57 milliseconds with a range from 200 to 530, that of antegrade effective refractory
period of slow pathway was 244 ± 45 milliseconds, and that of fast pathway was 313 ± 54 milliseconds. Anatomical area between the His catheter and the coronary sinus ostium in the left oblique anterior projection was divided into 5 areas: low posteroseptal, high posteroseptal, low midseptal, high midseptal, and anteroseptal. The suitable site for ablation was identified according to electeroanatomical mapping by multicomponent A wave and A/V ratio of less than 0.5. RF energy was applied with 50 W energy and 60°C temperatures. All the burns that lasted for more than 15 seconds were included; and after each RF energy application, the inducibility of AVNRT was reexamined with the same protocol, which was used for induction. If AVNRT was noninducible, isoproterenol infusion was started and inducibility was rechecked. In some cases, after applying a few RF energy (b15 seconds) using electeroanatomical approach at the site of recorded slow pathway potential if no JR was observed, programmed stimulation was performed to reassess the inducibility of the AVNRT. If tachycardia was not inducible, RF energy was applied for 60 seconds despite the absence of JR. Success was agreed only if AVNRT was noninducible after isoproterenol infusion. Residual slow pathway conduction, demonstrated as a single AV nodal echo, was present in 65 patients. In the remaining 24 patients, there was no evidence of residual slow pathway activity. After each RF application, the patterns of JR were analyzed according to the following definitions: (1) JJJ (junction-junction-junction) pattern: JR span is more than 95% of total time of each application of RF energy and lasts more than 15 seconds. It could even persist after interruption of RF application. (2) SJS (sinus-junction-sinus) pattern: JR appears after at least 5 sinus beats and persists during RF energy delivery. It is terminated by more than 5 sinus beats before the cessation of RF application. (3) SJJ (sinus-junction-junction) pattern: JR appears after more than 5 sinus beats and persists up to cessation of the RF application. (4) Intermittent burst: individual bursts of JR (at least 5 beats in each burst) with more than 5 sinus beats between bursts that intermittently appear during RF energy delivery. (5) Sparse: the junctional ectopy appears in a sparse pattern (N5 ectopies during each burst). (6) No junction: absence of JR during RF energy delivery. (7) SJB (Sinus Junction Block) pattern: the RF energy delivery interrupted after the appearance of ventriculoatrial block or AV block during JR. Statistical analysis Data were analyzed with Statistical Package for the Social Sciences (SPSS, Chicago, IL) software (version 13) using conventional methods for mean and SDs and nonparametric tests to evaluate group differences. Univariate and
M.H. Nikoo et al. / Journal of Electrocardiology 41 (2008) 39–43
multivariate analyses with a stepwise logistic regression model were performed to analyze variables that could predict the success of RF ablation. A P value of less than .05 was considered significant. Results All the patients had a successful outcome of noninducibility of AVNRT. The mean number of RF applications was 1.43 ± 0.6, and the cumulative energy was 3757 ± 0.6 J. The incidence and characteristics of the JR are shown in Table 1. Junctional rhythm appeared during 82 (94.25%) of 87 effective applications of RF energy and in 26 (65%) of 40 ineffective applications. The incidence of JR was significantly higher during effective application of RF energy than during ineffective application (P = .001). The mean number of junctional ectopy was 19.6 ± 18.8 (range, 75). The mean cycle length of the JR was 405.5 ± 215.1. The total number of junctional ectopy was significantly higher during effective applications of RF energy than during ineffective applications (24.6 ± 18.8 vs 8.4 ± 13.1; P b .001). We found that the number of junctional ectopy (N20) was significantly associated with the successful RF ablation (P b .001). We also found a significant difference between the effective and ineffective applications of RF energy in the mean cycle length of the JR (464.6 ± 167.5 vs 263.4 ± 250.2; P b .01). The patterns of JR were assessed and compared between effective and ineffective RF applications. Incidence of different patterns of JR is shown in Table 2. We succeeded in showing a significant correlation between junctional patterns and successful ablation (P = .01). Logistic regression analysis revealed that the presence of SJS, SJJ, and SJB patterns of JR were a predictor of a successful RF ablation (confidence interval [CI], 1.67-15.92 [P b .004]; CI, 1.02-85.62 [P = .048]; and CI, 1.06-32.02 [P = .042], respectively) (Fig. 1). Of 127 RF applications, we identified 23 burns that caused block in antegrade or retrograde conductions, of which 11 were antegrade and 10 were retrograde; 2 patients had both types. All of those blocks were transient, none of them lasting more than a few seconds. Mean temperatures and total applied energy were similar between the different patterns of JR (P = .26 and P = .8, respectively). Over a follow-up period of 9 months, AVNRT recurred in 1 patient. Table 1 Incidence and characteristics of junctional ectopy during RF ablation of slow pathway in patients undergoing RF ablation of slow pathway Effective applications
Ineffective applications
P
Total no. of junctional ectopy 24.65 ± 18.78 8.38 ± 13.16 b.001 Cycle length of junctional 464.64 ± 167.54 263.43 ± 250.24 b.01 ectopy (ms) Values are expressed as mean ± SD.
41
Table 2 Incidence of different junctional ectopy patterns during applications of RF energy in patients undergoing slow pathway ablation
Sparse SJS No junction SJB SJJ Intermittent burst JJJ
Effective applications
Ineffective applications
Total
n
n
n (%)
27 30 5 10 8 7 1
14 6 14 2 1 0 1
41 (32.5) 36 (28.3) 19 (15.0) 12 (9.4) 9 (7.1) 7 (5.5) 2 (1.6)
Most of the target sites at which junctional ectopy occurred was at high posteroseptal (62%) (Fig. 2). There was also no correlation between delivery sites and total RF energy applied and junctional patterns (P = .87 and P = .69, respectively). Discussion Main findings The characteristics of junctional ectopy during RF ablation of slow pathway have already been evaluated in association with the outcome of catheter ablation and inadvertent development of an AV conduction disturbances.7 However, no previous studies have so far compared the patterns of junctional ectopy occurring during effective applications of RF energy in patients undergoing slow pathway ablation. In the present study, we managed to show that successful ablation could be predicted by patterns of JR. We believed that such a detailed analysis might allow us to propose an additional marker of successful ablation. Applications of RF energy successful in eliminating AVNRT were associated with junctional ectopy characterized by different patterns of SJS, SJJ, and SJB, as described above. Therefore, quantization and quantification of the junctional ectopy proved useful in predicting the success of RF ablation. The area of posterior input into the AV node is complex, and the slow pathways may differ in different patients undergoing RF ablation of AVNRT, which could explain the different patterns of JR emerging during RF ablation. Characteristics of junctional ectopy associated with successful radiofrequency ablation As reported in previous studies,8,9 junctional ectopy was found to be a sensitive but nonspecific marker of successful ablation. Mcgavigan et al10 demonstrated that successful ablation of slow pathway seldom occurs in the absence of JR. Although JR almost invariably occurs with successful ablation, its lack of specificity and low positive predictive value questions its use as an end point. The occurrence of junctional ectopy during 64% of ineffective applications of RF energy in our series indicates that junctional ectopy is nonspecific marker of successful slow pathway ablation. Lee et al11 showed that there were different characteristics
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Fig. 1. Example of SJJ pattern of junctional ectopy during RF ablation of slow pathway. Tracings are surface electrocardiogram leads I, III, and V1 and intracardiac recordings from the ablation catheter. HRA indicates high right atrium; HBP, proximal His bundle; HBD, distal His bundle; RVA, right ventricular apex; CS, coronary sinus.
of the JR during slow pathway ablation of different types of AVNRT. Jentzer et al12 demonstrated that the quantification of junctional ectopy that occurs during delivery of RF energy are unlikely to be clinically useful in predicting whether a particular application was effective in eliminating the inducibility of AVNRT. In their study, there was no difference in the mean cycle length of the junctional ectopy occurring during effective and ineffective applications of RF energy, and although the bursts of junctional ectopy were significantly longer at the effective sites, the difference was relatively small in absolute terms. They reported a greater total number of junctional beats during the applications. In contrast with this study, we found a significant difference between the effective and ineffective applications of RF energy in the mean cycle length of the junctional ectopy (464.64 ± 167.54 vs 263.43 ± 250.24; P b .01). Wagshal et al,13 in their study, compared different patterns of AJR. They concluded that the much longer cycle length of the AJR associated with slow pathway ablation (604 ± 150 milliseconds) would argue against far-field activation of the compact AV node as the source of AJR. Lakobishvili et al14 found that the amount and duration of AJR is correlated with the total abolishment of slow pathway conduction. They presumed that a higher amount and duration of AJR might be an additional marker of successful ablation. Our study confirmed this finding about a greater number of junctional beats during effective RF applications. We also demonstrated that the number of junctional
ectopy (N20) is significantly associated with the successful ablation (P b .001). Poret et al15 demonstrated that midseptal ablation site is associated with a higher rate of AJR than posterior ablation site, suggesting that its origin is located close to the AV node. In our study, most of the target sites at which RF energies were applied and junctional ectopy appeared were located at
Fig. 2. Radiographic localization of catheter ablation at high posteroseptal area (P2). RA indicates right atrium; RV, right ventricle; RAO, right anterior oblique view.
M.H. Nikoo et al. / Journal of Electrocardiology 41 (2008) 39–43
the high posteroseptal area, but there was no association between the target sites of RF energy delivery and the patterns of junctional ectopy. Therefore, the pattern of junctional ectopy was not a site-dependent phenomenon. The pattern of “no junction” was observed in 15% (n = 19); but successful slow pathway ablation was possible in the absence of JR only in 5 cases. In these patients, a previous application had been associated with junctional beats. In our study, we excluded the patients with more than 5 RF deliveries, but the influence of previous RF deliveries could not be eradicated completely and it is a limitation of this study. In summary, this study confirms that JR is often present during a successful slow pathway ablation. There are distinct patterns of AJR as an indicator of a successful ablation. It could be helpful especially in patients in whom postablation study is difficult such as in patients without demonstrable dual AV nodal physiology or inducible tachycardia. References 1. Calkins H, Young P, Miller JM, et al. Catheter ablation of accessory pathway, atrioventricular nodal re-entrant tachycardia, and the atrioventricular junction: final results of a prospective, multicenter clinical trial. Circulation 1999;99:262. 2. Clague JR, Dagre N, Kottkamp H, et al. Targeting the slow pathway for atrioventricular nodal re-entrant tachycardia: initial results and long term follow-up in 379 patients. Eur Heart J 2001;22:82. 3. Wathen M, Natale A, Wolfe K, Yee R, Newman D, Klein G. An anatomically guided approach to atrioventricular node slow pathway ablation. Am J Cardiol 1992;70:886. 4. Thibault B, de Bakker JMT, Hocini M, Loh P, Wittkampf FHM, Janse MJ. Origin of heat-induced accelerated junctional rhythm. J Cardiovasc Electrophysiol 1998;9:631.
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5. Kelly PA, Mann DE, Alder SW, Fuenzalida CE, Bailey WM, Ritter MJ. Predictors of successful radiofrequency ablation of extranodal slow pathways. PACE 1994;17:1143. 6. Yu JCL, Lauer MR, Young C, Liem LB, Hou C, Sung RJ. Localization of the origin of the atrioventricular junctional rhythm induced during selective ablation of slow pathway conduction in patients with atrioventricular node re-entrant tachycardia. Am Heart J 1996;131:937. 7. Thakur RK, Klein GJ, Yee R, Stites HW. Junctional tachycardia: a useful marker during radiofrequency ablation for atrioventricular node reentrant tachycardia. J Am Coll Cardiol 1994;22:1706. 8. Jackman WM, Beckman KJ, McClelland JH, et al. Treatment of supraventricular tachycardia due to atrioventricular nodal reentry by radiofrequency catheter ablation of slow pathway conduction. N Engl J Med 1992;327:313. 9. Kay GN, Epstein AE, Dailey SM, Plumb VJ. Selective radiofrequency ablation of the slow pathway for the treatment of atrioventricular nodal reentrant tachycardia: evidence for involvement of perinodal myocardium within the reentrant circuit. Circulation 1992;85:1675. 10. Mcgavigan AD, Rae AP, Cobbe SM, Rankin AC. Junctional rhythm—a suitable surrogate endpoint in catheter ablation of atrioventricular nodal reentry tachycardia? PACE 2005;28:1052. 11. Lee SH, Tai CT, Lee PC, et al. Electrophysiological characteristics of junctional rhythm during ablation of slow pathway in different types of atrioventricular nodal reentrant tachycardia. PACE 2005;28:111. 12. Jentzer JH, Goyal R, Williamson BD, Man C, Niebauer M, Daoud E. Analysis of junctional ectopy during radiofrequency ablation of the slow pathway in patients with atrioventricular nodal tachycardia. Circulation 1994;90:2820. 13. Wagshal AB, Crystal E, Katz A. Patterns of accelerated junctional rhythm during slow pathway catheter ablation for atrioventricular nodal re-entrant tachycardia: temperature dependence, prognostic value, and insights into the nature of the slow pathway. J Cardiovasc Electrophysiol 2000;11:244. 14. Lakobishvili Z, Kusniec J, Shohat-Zabarsky R, Mazur A, Battler A, Starsberg B. Europace 2006;6:588. 15. Poret P, Leclercq C, Gras D, et al. Junctional rhythm during slow pathway radiofrequency ablation in patients with atrioventricular nodal re-entrant tachycardia. J Cardiovasc Electrophysiol 2000;11:405.