Atrioventricular Nodal Reentrant Tachycardia Ablation Research Articles

Slow Pathway Radiofrequency Ablation in Patients with AVNRT: Junctional Rhythm is Less Frequent during Magnetic Navigation Ablation Than with the Conventional Technique

The occurrence of accelerated junctional rhythm (JR) during radiofrequency ablation of the slow pathway in patients with atrioventricular nodal reentrant tachycardia (AVNRT) is frequent. The aim of the present study was to compare the occurrence of JR during magnetic remote catheter ablation to the conventional manual ablation. Twenty six patients (males: seven; age: 51 + or - 15 years) underwent slow pathway ablation with magnetic navigation (MN) system (Niobe, Stereotaxis Inc., St. Louis, MO, USA) and were compared to a control group of 11 patients (males: three; age: 53 + or - 16 years) treated with conventional manual ablation. A 4-mm nonirrigated tip catheter was used in both groups with a maximum of 30 W and 60 degrees C. Acute success was obtained in all patients. In the MN group, three patients out of 24 had no junctional beat (JB) at all and seven patients had 10 or less JB. In contrast, in the conventional group no patient had less than 10 JB. The mean number of JB in the MN group was 66 + or - 94.9 (0-410) and 200 + or - 243.1 (43-914) in the control group (P = 0.019). In the MN group one patient had a first-degree atrioventricular block. No other complication occurred. Magnetic remote catheter ablation of AVNRT is effective and is associated with less JB than the manual conventional technique. Therefore, JB may not be considered as a mandatory indicator for successful AVNRT ablation with MN system.

Radiofrequency Ablation of Pediatric AV Nodal Reentrant Tachycardia during the Ice Age: A Single Center Experience in the Cryoablation Era

Radiofrequency catheter ablation of atrioventricular nodal reentrant tachycardia (AVNRT) has proven to be an effective therapy in the pediatric population. However, concerns of inadvertent permanent AV nodal block have resulted in many pediatric programs adopting cryoablation as their primary ablation approach for AVNRT. A retrospective analysis of the results of pediatric radiofrequency catheter ablation at a single institution over the most recent 5 years (January 2004 through December 2008) was performed. Acute, intermediate, and long-term success, along with the incidence of AV block, were determined. There were 65 patients with a mean age of 12.1 + or - 5.2 years and weight of 46.5 + or - 17.3 kg who underwent radiofrequency catheter ablation for AVNRT. There was 100% acute success with no recurrences at a mean follow up of 32.5 months. Although two patients had a brief second-degree AV block, there was no permanent AV block of any degree. The safety and efficacy of radiofrequency catheter ablation for pediatric AVNRT demonstrated in this study support its continued application and should not be abandoned as a method of treatment.

Safety and feasibility of catheter ablation for atrioventricular nodal re-entrant tachycardia without fluoroscopic guidance

Nonfluoroscopic intracardiac navigation systems reduce the dose of radiation in most ablation procedures. However, they have not been sufficiently studied as a sole guidance tool for electrode catheter handling. The purpose of our study was to assess the feasibility and safety of catheter ablation for atrioventricular nodal re-entrant tachycardia (AVNRT) without the use of fluoroscopy. We prospectively enrolled all of the patients with AVNRT (Group A) treated by catheter ablation guided only by a nonfluoroscopic intracardiac navigation system. These patients were compared with a matched control group of patients (Group B) who had undergone an ablation procedure for AVNRT guided only by fluoroscopy in the preceding months. We compared the success rate and the rate of complications and recurrences. We also compared the procedure and radiofrequency times. Fifty patients were enrolled in each group. The procedure was successful in 100% in Group A versus 96% in Group B (P = .15). One patient in Group A and 4 patients in Group B suffered nonserious complications (P = NS). The mean fluoroscopy time in Group B was 18 +/- 16 min (range 3.5 to 77, total 924). In 1 case in Group A (2%), the use of fluoroscopy was required. Procedure and radiofrequency times did not differ between the 2 groups. A recurrence developed in 2 patients in each group (P = NS). Catheter ablation for AVNRT without fluoroscopic guidance is feasible and safe, and does not prolong procedure time. The reduction in radiation dose is considerable for patients and professionals.

Ablation of Atrioventricular Nodal Reentrant Tachycardia Using Remote Magnetic Guidance (Stereotaxis ®) Requires Lower Temperature and Power Settings Because of Improved Local Contact

The Stereotaxis(R) remote magnetic navigation system provides a new approach to ablation that could increase catheter stability. The aim was to determine whether improved tissue contact necessitates a change in traditional radiofrequency ablation parameters. The study compared ablation of atrioventricular nodal reentrant tachycardia (AVNRT) using remote navigation (4-mm catheter) in 19 patients with conventional ablation in 18 patients (4-mm catheter, temperature 60-65 degrees C, power 50 W). The radiofrequency energy needed to ensure that no more than a single nodal echo beat could be induced was measured. Charring was observed with traditional parameters on the first applications of the remotely navigated catheter. Hence, the energy was subsequently reduced (to 50 degrees C and 40 W). There was no difference in the number of applications between remote navigation and conventional groups (median: 6 vs. 8.5; interquartile range [IQR]: 11 vs. 9). Applications lasting <or=5 s were usually due to catheter dislodgment. Only four patients in the remote group had applications <or=5 s compared with 11 in the conventional group (P=.041). Ablation using remote navigation was equally effective and required lower temperatures and powers (mean+/-SD temperature: 46+/-2 degrees C vs. 50+/-4 degrees C, P< .001; median [IQR] power: 29 [14] W vs. 50 [7] W, P< .001), with no difference in total energy delivered. With remote navigation, the range of impedance values between applications was less (mean+/-SD: 10.4+/-7.6 Omega vs. 19.3+/-15.4 Omega; P=.035) and the temperature variation tended to be less, suggesting greater stability between applications. There were no complications. In this initial series, remote magnetic navigation was safe and effective in AVNRT ablation. Improved tissue contact reduced catheter dislodgment and necessitated a reduction in radiofrequency energy to avoid charring.

Treatment of atrioventricular nodal re-entrant tachycardia by cryoablation with a 6 mm-tip catheter vs. radiofrequency ablation

To compare recurrence rate and other procedural characteristics in patients undergoing atrioventricular nodal re-entrant tachycardia (AVNRT) treatment with catheter cryoablation (CRYO) delivered by 6 mm-tip catheter or radiofrequency (RF) ablation. This is a retrospective case-control study including 80 patients with AVNRT treated with CRYO from March 2002 to June 2008. They were compared with another 80 consecutive patients who underwent RF ablation for AVNRT within the same period. Procedural success of 97.5 and 95% were achieved in CRYO and RF group, respectively. There was no permanent atrioventricular block (AVB) in the CRYO group, whereas two (2.5%) patients developed permanent first-degree or second-degree AVB in RF group (P = 0.155). Higher recurrence was found in the CRYO group (9 vs. 1.3%; P = 0.032) with no difference in the composite endpoint of procedural failure and recurrence between the groups (P = 0.263). There was significantly shorter fluoroscopy time (18.6 +/- 10.8 vs. 25.9 +/- 17.0 min; P = 0.002) and more energy applications required (3.1 +/- 1.7 vs. 1.9 +/- 1.1; P < 0.001) in the CRYO than the RF group. Compared with RF ablation, CRYO with 6 mm-tip catheter for treating AVNRT results in higher recurrence and potentially lower incidence of permanent AVB. Fluoroscopy time has been shown to be reduced by CRYO.

ATRIOVENTRICULAR NODAL RE‐ENTRANT TACHYCARDIA ABLATION IN A CENTENARIAN

To the Editor: A 107-year-old independently living woman with no known cardiac disease presented with lightheadedness and frequent falls. She underwent an extensive examination, and eventually an electrophysiology (EP) study was performed that revealed easily inducible typical atrioventricular (AV) nodal re-entrant tachycardia (AVNRT). Slow pathway ablation was successfully performed. To the best of our knowledge, the patient described here is the oldest reported patient to undergo successful AVNRT ablation (Figure 1). Twelve-lead electrocardiogram of patient's supraventricular tachycardia. Findings suggest a short RP tachycardia. Arrows point to retrograde p waves seen particularly in leads aVL and V1. A 107-year-old independently living woman with no known cardiac disease presented to a cardiologist with complaints of lightheadedness and frequent falls over the previous 5 months. A transthoracic echocardiogram showed normal left ventricular function and mild mitral and aortic valve stenosis. Holter monitoring revealed nonsustained episodes of a narrow-complex tachycardia, with heart rates as high as 170 beats per minute. She was treated with a beta-blocker, which was later discontinued due to symptomatic bradycardia with heart rates as low as 35 beats per minute. One day while walking out of her home, without any prodrome, she had a syncopal event resulting in facial trauma. Because of the sudden nature of her collapse, an arrhythmia was thought to be the likely cause of her symptoms, so an electrophysiology (EP) study was performed. EP study showed dual AV nodal physiology and easily inducible typical AV nodal re-entrant tachycardia (AVNRT) (Figure 2), and slow pathway ablation was successfully performed. To further understand her reported syncopal episodes, and especially to evaluate for a bradycardic etiology, an implantable loop recorder (ILR) was also implanted. She had an uncomplicated postprocedural course and was eventually discharged to home. During 14 months of outpatient follow-up, no tachy- or bradyarrhythmias were noted on ILR interrogation, and no further syncope was noted. Intracardiac tracing tracing showing inducible typical atrioventricular nodal re-entrant tachycardia during electrophysiology study. AVNRT is the most common cause of supraventricular tachycardia. Catheter ablation of AVNRT is a class I recommendation of the American College of Cardiology and the American Heart Association for the long-term treatment of AVNRT.1 The safety and high efficacy of catheter ablation of AVNRT in patients aged 75 and older has been demonstrated.2 A case of AVNRT ablation in a 96-year-old woman has been reported.3 To the best of the authors' knowledge, the patient described here is the oldest reported patient to undergo successful AVNRT ablation. The ILR further served to exclude other dysrhythmias as a possible cause of her presyncopal symptoms. Clinicians often consider older patients to be poor candidates for invasive but potentially curative procedures based solely on their age. These patients are treated conservatively, resulting in suboptimal symptom control, which may then translate to greater morbidity and mortality. Medications may have a higher incidence of adverse effects in elderly people.4 Slow-pathway catheter ablation in an attempt to cure AVNRT should always be considered an option in elderly patients. Tachyarrhythmias less amenable to curative ablation, such as atrial tachycardia of a nonunifocal source or atrial fibrillation, are frequent in this age group. Furthermore, patients of all ages with unexplained symptoms of presyncope or syncope may benefit from continuous cardiac monitoring using an ILR. Conflict of Interest: The editor in chief has reviewed the conflict of interest checklist provided by the authors and has determined that the authors have no financial or any other kind of personal conflicts with this letter. James P. Daubert: Boston Scientific, honoraria for speaking; CV Therapeutics, advisory board; Medtronic, equity interest; Cryocor, consultant. Mehmet K. Aktas: Boston Scientific, honoraria. Author Contributions: Mehmet K. Aktas: acquisition of data, case report preparation and review. Stephen R. Tokarz: case report preparation and submission. James P. Daubert: acquisition of data, case report preparation and review. Sponsors' Role: None.

Atrioventricular node anatomy and physiology: implications for ablation of atrioventricular nodal reentrant tachycardia

Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common arrhythmia in patients with regular supraventricular tachycardia. Selective radio frequency catheter ablation of the slow pathway has afforded an ideal method to treat most patients with AVNRT. However, there are still some controversies and recent developments concerning the ablation for patients with AVNRT. The purpose of this review is to elucidate the anatomy and physiology of the atrioventricular node and implications for the ablation of AVNRT. The sequential ablation sites for slow pathway ablation are suggested as the isthmus between tricuspid annulus and coronary sinus ostium, the tricuspid edge of coronary sinus ostium by moving the ablation catheter tip slightly in and out of the coronary sinus, the septum lower than coronary sinus ostium, moving higher up on the half of Koch's triangle along the septum, one or two burns inside the first centimeter of the coronary sinus, left side of the septum. It is imperative to recognize the detailed anatomy and physiology of the atrioventricular node in every individual patient before the ablation of AVNRT.

Impact of Remote Magnetic Catheter Navigation on Ablation Fluoroscopy and Procedure Time

Remote magnetic catheter navigation (RCN) is gaining acceptance in clinical cardiac electrophysiology, but details regarding how RCN affects procedure execution are not well characterized. From January 1, 2005, to November 30, 2007, 721 cases were retrospectively analyzed and compared. Of these, 127 used RCN and 594 used manual catheter navigation (MCN). Data including procedure time, fluoroscopy time, ablation catheter, procedural success, and complications were extracted from our procedure database and compared between RCN and MCN. RCN use significantly decreased fluoroscopy time for atrial fibrillation (AF) ablation (-29 minutes, P < 0.001), atrioventricular nodal reentrant tachycardia ablation (-14 minutes, P < 0.001), and atrioventricular reentrant tachycardia ablation (-18 minutes, P = 0.045). While RCN significantly increased mean procedure time for AF (+36 minutes, P = 0.003) and atypical atrial flutter cases (+116 minutes, P = 0.016), RCN AF procedure time diminished with increasing number of cases performed. Two cases of tamponade occurred during AF ablation using MCN (2.2%, 2 of 91 cases). No tamponade occurred during all 75 AF ablations with RCN. RCN can reduce fluoroscopy time and may reduce complications during catheter ablation. While it may increase total procedure duration, procedure times decrease with increasing operator experience. (PACE 2008; 31:1399-1404).

Experience and Results During Transition from Radiofrequency Ablation to Cryoablation for Treatment of Pediatric Atrioventricular Nodal Reentrant Tachycardia

Cryoablation has emerged as a new, theoretically safer, modality for treating atrioventricular nodal reentrant tachycardia (AVNRT). The purpose of this study is to compare procedural aspects and outcomes during the transition from radiofrequency (RF) ablation to cryoablation for pediatric AVNRT. Data were obtained retrospectively from 80 consecutive pediatric patients who underwent AVNRT ablation from 10/2001- 4/2006 (RF n = 42, Cryo n = 38). Statistical analysis was performed using unpaired t-test, chi-square test, and analysis of variance. RF ablations were performed anatomically in NSR while three different mapping techniques were used during cryoablation: ablation during AVNRT (26%), anatomic in NSR (48%), and anatomic with S(1) S(2) pacing (26%). There was no difference in the number or duration of lesions between the three cryo subgroups. Acute success was obtained in 95% of RF and 97% of cryo cases. There was no difference in the number of total, mapping, or full-duration lesions between the RF and cryogroups. Despite accounting for longer cryolesion time, total ablation time (P < 0.001), mapping time (P = 0.002), and full duration lesion time (P < 0.001) were longer in the cryogroup. There was no significant difference in total procedure time; fluoroscopy time was shorter in the cryoablation group (P = 0.049). There was one confirmed recurrence of tachycardia in each group with a 2% recurrence rate. Cryoablation for treatment of pediatric AVNRT is as safe and efficacious as RF ablation. Although cryolesions are intrinsically longer in duration, total procedure times were not increased and fluoroscopy times were decreased compared to RF.

Successful slow pathway ablation for atrioventricular nodal re-entrant tachycardia via a hypoplastic inferior vena cava in a patient with an azygos continuation

Catheter ablation of the slow pathway for atrioventricular nodal re-entrant tachycardia (AVNRT) is not always possible due to congenital or acquired obstruction of the inferior vena cava (IVC). Although a superior access has been proposed as an alternative approach, a poor manoeuvrability and a lower stability of the ablation catheter may be potential problems. We report a case of slow pathway ablation for AVNRT in a patient with an azygos continuation using a hypoplastic but uninterrupted IVC.

Rapid Atrial Pacing: A Useful Technique During Slow Pathway Ablation

Catheter ablation is the treatment of choice for atrioventricular nodal reentrant tachycardia (AVNRT) with a success rate of 95-98%. The appearance of junctional rhythm during radiofrequency (RF) application to the slow pathway has been consistently reported as a marker for the successful ablation of AVNRT. Ventriculoatrial (VA) conduction during junctional rhythm has been used by many as a surrogate marker of antegrade atrioventricular nodal (AVN) function. However, VA conduction may not be an accurate or consistent marker for antegrade AVN function and reliance on this marker may leave some patients at risk for antegrade AVN injury. The purpose of this study is to describe a technique to ensure normal antegrade AVN function during junctional rhythm at the time of RF catheter ablation of the slow pathway. Retrospective review of all patients less than 21 years old who underwent RF ablation for AVNRT at our institution from January 2002 to July 2005. During RF applications, immediately after junctional rhythm was demonstrated, RAP was performed to ensure normal antegrade AVN function. Postablation testing was performed to assess AVN function and tachycardia inducibility. Fifty-eight patients underwent RF ablation of AVNRT during the study period. The mean age +/- SD was 14 +/- 3 years (range: 5-20 years). The weight was 53 +/- 15 Kg (range: 19-89 Kg). The preablation Wenckebach cycle length was 397 +/- 99 msec (range: 260-700 msec). Fifty-four patients had inducible typical AVNRT, and four patients had atypical tachycardia. The mean tachycardia cycle length +/- SD was 323 +/- 62 msec (range: 200-500 msec). Patients underwent of 8 +/- 7 total RF applications (median: 7; range 1 to 34), for a total duration of 123 +/- 118 seconds (median: 78 sec, range: 20-473 sec). Junctional tachycardia was observed in 52 of 54 patients. RAP was initiated during junctional rhythm in all patients. No patient developed any degree of transient or permanent AVN block. Following ablation, the Wenckebach cycle length decreased to 364 +/- 65 msec (P < 0.01). Acutely successful RF catheter ablation was obtained in 56 of 58 patients (96%). Rapid atrial pacing during radiofrequency catheter ablation of the slow pathway is a safe alternative approach to ensure normal AVN function.

Atrioventricular Nodal Reentrant Tachycardia in the Elderly: Efficacy and Safety of Radiofrequency Catheter Ablation

Radiofrequency (RF) catheter ablation is considered the treatment of choice for patients with atrioventricular nodal reentrant tachycardia (AVNRT). This study examined the efficacy and safety of RF ablation in patients with AVNRT >/= 65 years of age. We retrospectively analyzed data collected in 350 consecutive patients who underwent AVNRT RF ablation between 1995 and 2005. They were divided according to whether they were < 65 years (Group 1, n = 280; mean age = 46 +/- 13 years, 69% women) or >/= 65 years (Group 2, n = 70; mean age = 72 +/- 6 years, 59% women) of age. Patients in Group 2 more often had structural heart disease (12/70 vs 17/280, P = 0.002) than in Group 1, though there was no difference in the prevalence of syncope (6/70 vs 18/280, P = 0.52) or atrial fibrillation (1/70 vs 6/280, P = 0.70) between the 2 groups. Before RF ablation, patients in Group 2 had a longer mean A-H intervals (90 +/- 31 ms vs 77 +/- 19 ms, P < 0.0001), H-V intervals (44 +/- 6 ms vs 41 +/- 5 ms, P < 0.0001), fast pathway refractory period (358 +/- 14 ms, vs 335 +/- 68 ms, P = 0.01), and tachycardia cycle length (394 +/- 71 ms vs. 335 +/- 59 ms, P < 0.0001). A > 140 ms A-H interval was present in 3/70 patients in Group 2 versus 0/280 in Group 1 (P < 0.001). No difference was observed between the 2 groups in primary RF ablation success rate (70/70 vs 277/280, P = 0.38), overall procedure duration (75 +/- 35 minute vs 78 +/- 43 minute, P = 0.61), duration of fluoroscopic exposure (14 +/- 12 minute vs 13 +/- 12 minute, P = 0.63), or number of RF pulses (median 5 vs 4, P = 0.051). Two patients in Group 1 (0.57%) developed 3rd degree AV block requiring permanent pacing. Recurrences of AVNRT were limited to Group 1 (16/280 vs 0/70, P = 0.001). RF ablation of AVNRT was highly effective and safe in patients >/= 65 years of age despite a higher prevalence of structural heart disease and longer A-H intervals at baseline. RF ablation might be considered as first-line therapy for the elderly with AVNRT.

The electrophysiologic characteristics of atrioventricular nodal reentry tachycardia with eccentric retrograde activation

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.

Noncontact three-dimensional mapping guides catheter ablation of difficult atrioventricular nodal reentrant tachycardia

Background Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common supraventricular tachycardia in adulthood. Although selective ablation of the slow AV nodal pathway can cure AVNRT, accidental AV block may occur. The details on the electrophysiologic characteristics, quantitative data on the voltage inside Koch's triangle, and the use of three-dimensional noncontact mapping to facilitate the catheter ablation of AVNRT associated with a high-risk for AV block or other arrhythmias have been limited. Methods and results Nine patients ( M/ F = 5/4, 34 ± 23 years, range 17–76) with clinically documented AVNRT were included. All patients had undergone previous sessions for slow AV nodal pathway ablation but they had failed, because of repetitive episodes of complete AV block during the RF energy applications. Further, one patient had a complex anatomy and 4 patients were associated with other tachycardias, respectively. The electrophysiologic studies revealed that 4 patients had the slow–fast, 4 the slow–intermediate and one the fast–intermediate form of AVNRT. Noncontact mapping demonstrated two types of antegrade AV nodal conduction, markedly differing sites of the earliest atrial activation during retrograde VA conduction, and a lower range of voltage within Koch's triangle. The lowest border of the retrograde conduction region was defined on the map, and the application of the RF energy was delivered below that border to prevent the occurrence of AV block. The distance between the successful ablation lesions and the lowest border of the retrograde conduction region was significantly shorter in the patients with the slow–intermediate form of AVNRT than in those with the slow–fast form (5.5 ± 3.4 vs. 15 ± 7.6 mm; p < 0.05). After the ablation procedure, either rapid pacing or extrastimulation could not induce any tachycardia, and there was no recurrence during the follow-up (10.3 ± 5.4, 2 to 22 months). Conclusions Noncontact mapping could effectively demonstrate the antegrade and retrograde atrionodal conduction patterns, electrophysiologic characteristics of Koch's triangle, and guide the successful catheter ablation in difficult AVNRT cases.

Atrioventricular Nodal Reentrant Tachycardia in Patients Referred for Atrial Fibrillation Ablation

Although the most common sites of atrial ectopy that trigger atrial fibrillation (AF) are in or around the pulmonary veins (PVs), atrioventricular nodal reentrant tachycardia (AVNRT) can also cause or coexist with AF. We sought to characterize patients with AF and AVNRT and assess clinical outcomes after ablation. To determine the prevalence of concomitant AVNRT and AF, 629 consecutive patients referred for catheter ablation between November 1998 and March 2005 were studied. Electrophysiological studies with programmed stimulation during isoproterenol infusion identified atrial ectopy that initiated AF and the presence of inducible AVNRT. AF ablation consisted of proximal isolation of PVs and elimination of any non-PV trigger of AF, including AVNRT. There were 27 patients (4.3%) who had inducible AVNRT at the time of AF ablation. Of these, 13 underwent AVNRT ablation without PV isolation. Compared with the rest of the cohort, patients with AVNRT and AF were younger at the time of symptom onset (age 36.8+/-13.8 versus 48.2+/-11.7 years; P<0.01). Freedom from AF with or without previously ineffective antiarrhythmic medication was similar in both groups (96.3% versus 90.7%; mean follow-up 21.4+/-9.4 months); however, patients with AVNRT targeted for ablation were more likely to be AF free while not taking any antiarrhythmic medication after a single procedure during the follow-up period (87.5% versus 54.7%; P<0.01) and had fewer complications (0% versus 2.5%; P=0.30). Twelve of the 13 patients who underwent slow-pathway ablation without left atrial ablation remained AF free without the need for antiarrhythmic medication after a single procedure. AVNRT is an uncommon AF trigger seen more frequently in younger patients. Ablation of AVNRT in patients with AF was associated with improved outcomes compared with those with other triggers of AF.

Long-term efficacy and safety of radiofrequency ablation in elderly patients with atrioventricular nodal re-entrant tachycardia

The purpose of this study was to evaluate the efficacy, risks, safety, and follow-up of radiofrequency (RF) catheter ablation of atrioventricular nodal re-entrant tachycardia (AVRNT) in patients (pts) > or = 75 years old (n=42) (GpI) compared with pts younger than 75 years (n=234) (GpII). The study population consisted of 276 consecutive pts (39.5% men/60.5% women), from 15 to 98-year-old (average 56+/-17 years) with AVRNT referred for RF ablation (RFA) from October 1997 to January 2004. Combined anatomical and electrogram approaches were used to guide RFA. The cumulative risk of AVRNT recurrence was analysed by the Kaplan-Meier method and log-rank test. The average follow-up was 34+/-18 months. GpI (80+/-4 years) differed significantly from GpII (51+/-14 years) regarding: heart rate tachycardia (160+/-20 vs. 180+/-30 bpm; P=0.0001), the slow pathway antegrade refractory period (370+/-70 vs. 340+/-60 ms; P=0.01), the fast pathway antegrade refractory period (360+/-60 vs. 330+/-60 ms; P=0.003), retrograde refractory period (360+/-60 vs. 330+/-60 ms; P=0.0007), left ventricular ejection fraction (60+/-12 vs. 65+/-7%; P=0.0009), and ischaemic ECG signs during tachycardia (76.2% vs. 61%; P=0.09). RFA was successfully obtained in 275/276 (99.6%), 42/42 in GpI (100%), and 233/234 (99.6%) in GpII. Five complications occurred (1.8%): major complications in two pts (0.7%) and minor complications in three pts (1.1%). Major complications were deep venous thrombosis with pulmonary embolus (n=1) and pericardial effusion (n=1), minor complications were groin haematoma (n=3). One complication was observed in GpI (groin haematoma) (2.4%) and four in GpII (deep venous thrombosis with pulmonary embolus in one, groin haematoma in two, and pericardial effusion in one) (1.7%). The number of recurrences was not statistically different between the two groups (0 vs. 3.4%; P=0.5) with a respective average follow-up of 28+/-18 and 35+/-18 months, respectively. Catheter ablation of AVRNT in elderly and very elderly pts appears to be a reasonable approach regarding feasibility and effectiveness without increasing the risk of AV block.

Three‐Dimensional Image Integration: A First Experience with Guidance of Atrial Fibrillation Ablations

Editorial Comment The treatment of atrial fibrillation (AF) can be challenging, with a rate control strategy not being optimal for all patients and antiarrhythmic drugs frequently ineffective and possessing serious adverse effects. A fluoroscopic or electroanatomic catheter-based approach is rapidly becoming one of the preferred treatments of AF. 1-3 However, success rates are still not ideal and complications due to damage of extra thoracic structures remain a problem. 1 Also of concern is the significant ionizing radiation exposure during the prolonged fluoroscopy required to delineate the complex anatomy of the left atrium and pulmonary veins, even with advanced techniques to minimize exposure. Total fluoroscopy duration for AF ablations is typically 8-fold higher than atrioventricular nodal reentrant tachycardia ablations, averaging over 60 minutes of fluoroscopy time, with radiation exposure in the 1.0‐1.5 Gy range. 4 One of the major promises of using integratedmodality navigation systems such as this for AF ablation is faster, more accurate catheter navigation, reduced complications, and diminished fluoroscopy use. In view of the complex and variable anatomy of cardiac structures and pulmonary veins, many of which remain invisible to fluoroscopy, the addition of further, more accurate imaging modalities are likely to improve ablation success and safety. 5,6 While three-dimensional (3D) mapping techniques using magnetic or electrical localizing systems in the modern electrophysiology laboratory are extremely useful and are currently in widespread clinical use, they require catheter manipulation to identify geometry and do not provide independent anatomic information. Both magnetic resonance (MR) imaging 7,8 and computed tomography (CT) scanning 9,10 have been shown prior to be suitable for delineating the left atrial anatomy and assisting with catheter navigation. However, it is not yet clear which imaging modality is superior for mapping of the left atrium and other cardiac structures; certainly navigation and imaging systems that allow the use of either format will be advantageous.

Unique electrophysiologic characteristics of atrioventricular nodal reentrant tachycardia with different ventriculoatrial block patterns: Effects of slow pathway ablation and insights into the location of the reentrant circuit

The electrophysiologic mechanisms of different ventriculoatrial (VA) block patterns during atrioventricular nodal reentrant tachycardia (AVNRT) are poorly understood. The purpose of this study was to characterize AVNRTs with different VA block patterns and to assess the effects of slow pathway ablation. Electrophysiologic data from six AVNRT patients with different VA block patterns were reviewed. All AVNRTs were induced after a sudden AH "jump-up" with the earliest retrograde atrial activation at the right superoparaseptum. Different VA block patterns comprised Wenckebach His-atrial (HA) block (n = 4), 2:1 HA block (n = 1), and variable HA conduction times during fixed AVNRT cycle length (CL) (n = 1). Wenckebach HA block during AVNRT was preceded by gradual HA interval prolongation with fixed His-His (HH) interval and unchanged atrial activation sequence. AVNRT with 2:1 HA block was induced after slow pathway ablation for slow-slow AVNRT with 1:1 HA conduction, and earliest atrial activation shifted from right inferoparaseptum to superoparaseptum without change in AVNRT CL. The presence of a lower common pathway was suggested by a longer HA interval during ventricular pacing at AVNRT CL than during AVNRT (n = 5) or Wenckebach HA block during ventricular pacing at AVNRT CL (n = 1). In four patients, HA interval during ventricular pacing at AVNRT CL was unusually long (188 +/- 30 ms). Ablations at the right inferoparaseptum rendered AVNRT noninducible in 5 (83%) of 6 patients. Most AVNRTs with different VA block patterns were amenable to classic slow pathway ablation. The reentrant circuit could be contained within a functionally protected region around the AV node and posterior nodal extensions, and different VA block patterns resulted from variable conduction at tissues extrinsic to the reentrant circuit.

Cryoablation versus radiofrequency ablation for treatment of pediatric atrioventricular nodal reentrant tachycardia: Initial experience with 4-mm cryocatheter

Initial reports have shown cryoablation to be safe and efficacious for treatment of atrioventricular nodal reentrant tachycardia (AVNRT). No direct comparisons of cryoablation vs radiofrequency (RF) catheter ablation in pediatric patients have been made. The purpose of this study was to compare the outcomes of cryothermal vs RF catheter ablation for treatment of AVNRT in pediatric patients. We retrospectively reviewed consecutive ablation procedures for treatment of AVNRT at a single arrhythmia center. The RF group consisted of patients who underwent RF ablation from 2002 until cryothermy became available. The cryoablation group consisted of patients who underwent cryothermal ablation from 2004 to 2005. The groups were compared for procedural and electrophysiologic outcomes. RF (n = 60, age 14 +/- 4 years) and cryoablation (n = 57, age 14 +/- 4 years) groups had similar demographic and baseline parameters. Procedural times were shorter in the RF group (RF ablation 112 +/- 31 minutes vs cryoablation 148 +/- 46 minutes, P < .001). Fluoroscopy times were comparable (RF ablation 21 +/- 15 minutes vs cryoablation 20 +/- 13 minutes, P = .77). In an intention-to-treat analysis, success of the procedure was 100% for RF ablation and 95% for cryoablation (P = .11). No permanent AV block occurred in either group. Recurrence rates were higher for the cryoablation group, but this did not reach statistical significance (RF ablation 2% vs cryoablation 8%, P = .19). Cryoablation appears to be similar to RF for ablation of AVNRT with respect to short-term efficacy and safety of the procedure in a pediatric population. Recurrence rates are higher with cryoablation.

Seven-year follow-up after catheter ablation of atrioventricular nodal re-entrant tachycardia

Radiofrequency catheter ablation is considered to be a curative therapy for patients with atrioventricular nodal re-entrant tachycardia (AVNRT). Nevertheless, there is little information available with respect to long-term results and the consequences of catheter ablation. The present study aimed to assess the long-term results (a minimum of 5 years) and clinical events. The recurrence rate of AVNRT, the development of late atrioventricular block and the presence of other arrhythmias (atrial flutter and fibrillation) were assessed in 131 consecutive patients who were undergoing catheter ablation between January 1992 and December 1998. During a mean follow-up of 7.2 +/- 2.5 years, tachycardia recurred in 13 patients (10%) after a median time of 6 months (interquartile range 4-24 months) and a second procedure was perfomed. Atrioventricular block occurred in two patients (1.5%) after 1 and 13 months. Atrial fibrillation recurred in seven (44%) of 16 patients in whom atrial fibrillation or flutter was present before ablation after a median of 12 months (interquartile range 9-15 months). Overall, all these events occurred after a median of 9 months (interquartile range 4-17 months). Subsequently, no event related to the arrhythmia or to the procedure was observed. A new onset atrial fibrillation, probably not related to AVNRT, occurred late in the follow-up in a further three patients. Arrhythmic events are not infrequent after catheter ablation of AVNRT during the early years after ablation, but they are unlikely during the subsequent long-term follow-up.