Catheter Ablation Of Slow Pathway Research Articles

PO-05-146 AN UNUSUAL ATRIOVENTRICULAR REENTRY TACHYCARDIA: SUCCESSFUL ABLATION OF NOVEL SLOW PATHWAY AT SUPERIOR SEPTAL PERIMITRAL LEFT ATRIUM

Atrioventricular nodal reentrant tachycardia (AVNRT) is a common supraventricular tachycardia (SVT), treated with catheter ablation of slow pathway. The right and left inferior slow pathway (SP) extensions of the AV node are widely recognized, but other SPs are very rare. We present a case of atypical AVNRT that was successfully ablated at the superior septal perimitral left atrium. N/A A 75-year-old man with history of coronary artery disease status post coronary artery bypass grafting and recurrent episodes of symptomatic SVT despite diltiazem and metoprolol presented for catheter ablation. Mid RP SVT (cycle length, CL 350 ms) with concentric atrial activation was inducible with atrial and ventricular extrastimulation. Synchronized premature ventricular complexes and ventricular entrainment excluded AV reentry. Very late coupled premature atrial complex from coronary sinus (CS) delivered synchronous to septal A activation delayed next A and reset SVT indicating AVNRT and excluding ectopic junctional (JT) or atrial tachycardia (AT). Further, AH interval during SVT was much longer than AH with atrial pacing at same CL excluding AT. We concluded mechanism to be atypical AVNRT. On activation mapping of right atrium, earliest A was recorded in the fast pathway region, earlier than locations of right and left slow pathways in the triangle of Koch and CS respectively. Radiofrequency ablation lesions anatomically targeting both slow pathways were delivered at base of triangle of Koch and inside CS without affecting SVT. High density activation maps of both right and left atria were created during SVT using Orion basket catheter and Rhythmia (Boston Scientific) mapping system. Earliest A was recorded in the superior septal perimitral left atrium, superior to the location of His bundle electrogram, and anatomically adjacent to aortic sinuses of Valsalva (not mapped). We concluded this to be an unusual left superior extension of the AV node. Radiofrequency ablation lesion using IntellaNav MiFi catheter at this site promptly terminated SVT. Consolidation lesions were delivered and anchored to the mitral annulus. The tachycardia was no longer inducible on programmed electrical stimulation despite isoproterenol. The patient has remained symptom free for 6 months since ablation. With activation mapping we identified the retrograde slow pathway participating in an unusual atypical AVNRT at superior septal perimitral left atrium.

Success Rate in Patients with Atrioventricular Nodular Re-Entrant Tachycarida (AVNRT) Slow Pathway Catheter Ablation with and without Junctional Rythym

Background and Aim: For successful radiofrequency ablation of atrioventricular nodal reentrant tachycardia (AVNRT), slow-pathway radiofrequency catheter ablation leads to junctional rhythm (JR) is now being considered as a very sensitive substitute end goal. During AVNRT RF ablation, a favorable result could be predicted based on the pattern of JR produced. Patients and Methods: This cross-sectional study was conducted on 64 patients presenting with symptomatic AVNRT and undergoing slow-pathway RF ablation in the Department of Cardiology, Hayatabad Medical Complex, Peshawar for the duration from January 2022 to June 2022. RF ablation of slow pathway was performed using a combined anatomical and electrogram mapping approach. Ablation was performed by controlling the temperature and delivering energy over 60 seconds at 60°C. In order to determine if the developed JR was successful, isoproterenol infusion was performed after every ablation pulse. Four different patterns of AVNRT inducibility were considered: intermittent, continuous, sparse, and transient. Position, pattern, and number of junctional beats were used to assess the success rate of ablation. SPSS version 28 was used for descriptive statistics. Results: Of the total patients, there were 36 (56.2%) women and 28 (43.8%) men. The overall mean age was 38.64 ± 18.36 years with an age range 16-80 years. The most prevalent symptom during AVNRT was palpitation found in 41 (64.1%) cases. The prevalence of pre-syncope, dyspnea, and syncope was 3.8%, 3.8%, and 3.4% respectively. The incidence of more than one symptoms were found in 21 (32.8%) patients. Almost all the patients displayed antegrade AH jumps and indicated dual AV nodal conduction. Out of total 156 RF, it took 114 (73.1%) RF energy applications to successfully ablate 38 (59.4%) patients with loss of AVNRT inducibility. About 126 (80.8%) patients developed JR with given specificity 42.6%, sensitivity 89.6%, and negative predictive value 61.8%. Conclusion: The present study found that the JR predicts the success of AVNRT RF ablation at a high level of sensitivity, but not to a specific degree. However, the findings indicate that its specificity may rise with the appearance of > 14 total tight junctions beats. Furthermore, if the forecast of effective slow-route RF ablation in relation to the existence of JR remains not consistent adequate, its absence might be a trustworthy marker of the pathway needing greater energy application delivery to be abolished. Keywords: Atrioventricular nodular re-entrant tachycardia (AVNRT), Slow pathway catheter ablation, Junctional rhythm, success rate

Supraventicular tachycardia and atrial ectopic beats: electrophysiological findings in a patient after previous slow pathway ablation

In this case report we present electrophysiological features of supraventricular tachycardia in a 64-year-old patient after previous slow pathway catheter ablation; ECG features of the tachycardia and results of electrophysiological testing are discussed.

Three-dimensional mapping systems for radiofrequency catheter ablation of slow pathway for the treatment of atrioventricular nodal reentrant tachycardia: About 2 cases

Radiofrequency ablation (RFA) of the atrioventricular nodal reentrant tachycardia (AVNRT) is associated with the risk of complete atrioventricular (AV) block. This risk is majored by some anatomic conditions and remains a serious complication in young patients. Herein, we would like to report 2 cases of 3D mapping system use to guide RF ablation of AVNRT. This is a case of a 57-year-old man with a long medical history of atrial fibrillation (AF). He presented with palpitation and dyspnea. Physical examination was normal. On ECG, supraventricular tachycardia (SVT) with a heart rate of 144 beats per minute was noted. RFA was indicated because of the recurrence of this symptomatic tachycardia. CARTO 3D system mapping was used as the patient has a medical history of multiple ablated AF. RF delivery below the Coronary sinus (CS) ostium showed an accelerated junctional rhythm. No SVT was reproducible at the end of the procedure. A 50-year-old patient reported chest pain and dyspnea related to SVT. Physical examination and tranthoracic echocardiography were unremarkable. On ECG, a supraventricular tachycardia with long RP’ with ST depression was noted. Blood tests showed troponin elevation. Coronary angiography was normal. This patient had a long medical history of tachycardia that often starts and ends suddenly, not improved by beta-blockers treatment. RFA was indicated. RHYTHMIA Mapping system was used. The EP study reproduced the clinical tachycardia, which was a slow-slow AVNRT. RF delivery for 90 minutes below the CS ostium and 12 mm under the His bundle eliminated completely the slow pathway. The 3D mapping systems is an interesting tool for AVRNT RF ablation. It is correlated with lower radiation exposure and shorter procedure time. It may offer more security in young patient and those with a short distance between His bundle and CS ostium.

Clinical recurrence of palpitations following slow pathway ablation in patients with suspected paroxysmal supraventricular tachycardias but non-documented, non-inducible tachycardias

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Catheter ablation is recommended as first-line treatment in patients with atrioventricular nodal reentry tachycardias (AVNRT). However, the best therapeutic modality in patients with dual AV nodal physiology but non-inducible tachycardias in electrophysiological study (EPS) remains controversial, especially when no tachycardias have been documented. Our objective was to evaluate the results of empirical slow pathway ablation in patients showing dual AV nodal physiology but non-inducible AVNRT. Methods Multicenter, retrospective, observational registry of consecutive patients undergoing EPS due to clinical suspicion of paroxysmal supraventricular tachycardias (PSVT), but with no prior ECG documentation. Clinical, EPS and ablation (when performed) data were collected and andalyzed. Results 427 patients of 12 centers were included. Mean age was 46.3 ±16.1 and 297 (69.6%) were females. AVNRT was induced in 188 patients (typical in 181 cases, atypical in 7). Dual AV nodal physiology with or without single nodal echo beats, but with no sustained tachycardia and without evidence of accessory pathway was present in 68 patients. Ablation of the slow pathway was performed in 187/188 patients with AVNRT and in 30/68 patients with dual physiology. Among subjects with non-inducible tachycardia, ablation reduced significantly recurrences (39.5% in non-ablated vs. 16.7%; p = 0.04), with a level equivalent to those with ablated AVNRT(14.4% vs. 16.7%; p = 0.75). Procedure-related complications were similar in both groups: empirical ablation n = 1; 3.3% vs. induced tachycardia n = 6; 3.2% (p = 0.98). Conclusions In patients with high clinical suspicion of PSVT but non-documented and non-inducible arrhythmias, the presence of dual AV nodal physiology makes AVNRT a likely mechanism of the clinical tachycardia. Catheter ablation of slow pathway reduces the risk of recurrence to a level equivalent to those with inducible and ablated AVNRT. AVNRT (n = 188) Dual nodal physiology (n = 68) p value Age (years) 48.6 ± 16.3 41.9 ± 14.0 <0.01 Female 71.8% 67.7% 0.52 Years symptomatic 9.3 ± 11.3 3.6 ± 8.1 <0.01 Sudden onset 83.9% 88.0% 0.54 Abrupt end 73.4% 74.6% 0.96 Previous rate-slowing drugs 30.9% 25.0% 0.36 Previous antiarrhythmic drugs 5.9% 2.9% 0.35 Isoproterenol in EPS 70.0% 89.7% <0.01

Endpoints for Successful Slow Pathway Catheter Ablation in Typical and AtypicalAtrioventricular Nodal Re-Entrant Tachycardia: A Contemporary, Multicenter Study.

This study sought to investigate markers of success following slow pathway ablation for atrioventricular nodal re-entrant tachycardia (AVNRT). Published data are conflicting. The authors studied 1,007 patients with typical AVNRT and 77 patients with atypical AVNRT. Following ablation, tachycardia was rendered not inducible in all patients. One case of transient (0.09%) and 1 of permanent (0.09%) atrioventricular (AV) block were encountered. At a 3-month follow-up, arrhythmia recurrence was noted in 21 (2.10%) patients in the typical and 3 (3.90%) patients in the atypical group (odds ratio: 0.525; 95% confidence interval [CI]: 0.153 to 1.802; p= 0.298). To predict absence of recurrence in 3 months, the induction of junctional rhythm (95.70% in typical and 96.10% in atypical groups) had sensitivity of 95.9% (95% CI: 94.6% to 97.0%) and specificity of 4.20% (95% CI: 0.11% to 21.10%), while the absence of dual AV nodal conduction post-ablation had sensitivity of 65.2% (95% CI: 62.2% to 68.1%) and specificity of 33.30% (95% CI: 15.60% to 55.30%). Neither junctional rhythm nor residual dual AV nodal pathway conduction were predictive of arrhythmia recurrence by univariate analysis. In long-term follow-up data available for 239 patients, arrhythmia-free survival was not associated with the induction of junctional rhythm or the absence of residual dual AV nodal conduction (log-rank test, p= 0.819 and p=0.226, respectively). Induction of a junctional rhythm during ablation is a sensitive but not a specific marker of success. Residual dual AV nodal conduction is not predictive of recurrence. Noninducibility of the arrhythmia, usually after ablation-induced junctional rhythm, and despite isoproterenol challenge, is the most credible endpoint for success.

RECURRENCE OF TACHYCARDIA IN 8 YEARS AFTER RADIOFREQUENCY CATHETER ABLATIONOF SLOW PATHWAY OF ATRIOVENTRICULAR JUNCTION

In the article the clinical case of recurrence of typical atrioventricular nodal reentry tachycardia (AVNRT) in 8 years from the moment of a radiofrequency catheter ablation of slow pathway of atrioventricular junction concerning paroxysmal AVNRT at the patient of 42 years is described.

Slow pathway ablation for typical atrioventricular nodal re-entrant tachycardia significantly alters the autonomic modulation of atrioventricular conduction

Atrioventricular (AV) conduction turbulence, biphasic dromotropic response of AV node to single ventricular premature contraction (VPC), consists of early shortening and later prolongation of AV conduction intervals due to the direct electrophysiological mechanisms and perturbation in autonomic modulation. We investigated the acute effect of radiofrequency catheter ablation of slow pathway on AV turbulence. The electrophysiological study was performed in 18 patients (7 men, mean age 49±15years) undergoing catheter ablation for AV nodal reentrant tachycardia. The stimulation protocol consisting of series of isolated VPC (coupling interval of 273±23ms) delivered from right ventricle apex during constant atrial pacing at 100bpm was performed immediately prior to and 8±4min after successful slow-pathway ablation. Averaged post-VPCs profiles of AV conduction intervals were analyzed by purpose-written software. The descriptors of AV turbulence, turbulence onset (TOAV), turbulence slope (TSAV), and AV recovery (R AV) were assessed. Slow-pathway ablation suppressed the AV nodal responsiveness to VPC as evidenced by significant reduction of AV turbulence indices: TOAV: -6.4±7.5% vs. -4.3±6.1% (p<0.05); TSAV: 2.0±2.6ms/RRi vs. 1.0±0.7ms/RRi (p<0.05); and R AV: -13.8±7.3% vs. -6.5±12.7% (p<0.05). Slow-pathway ablation significantly attenuated both vagal and non-autonomic modulation of AV nodal conduction. This effect is likely due to direct thermal injury of AV node associated with the change of properties of AV nodal fast-pathway although specific alteration of peri-AV nodal ganglionated plexi or their neural inputs into the AV node cannot be excluded.

Ivabradine in the Treatment of Inappropriate Sinus Tachycardia in Patients after Successful Radiofrequency Catheter Ablation of Atrioventricular Node Slow Pathway

Inappropriate sinus tachycardia (IST) occurs relatively common after catheter ablation of slow pathway in patients with atrioventricular nodal reentrant tachycardia. The treatment of IST symptoms using β-blockers or calcium channel-blockers are often noneffective or not well tolerated. Ivabradine is a new heart rate (HR)-decreasing agent inhibiting sinus node If current. The purpose of the study was to evaluate the efficacy and safety of ivabradine in patients with persistent and β-blocker-resistant IST after successful radiofrequency (RF) ablation of atrioventricular node slow pathway. We enrolled 14 patients (42 ± 11 years; 10 women) affected by IST after RF ablation. Holter monitoring, treadmill stress test, and IST symptoms assessment were performed at baseline and after first, and second month of the study. We observed significant reduction of mean resting HR after 30 and 60 days of ivabradine treatment compared to baseline (P < 0.001). 24-hour Holter monitoring showed a significant reduction of mean HR and mean HR during daily activity (P < 0.001). The study revealed significant improvement in exercise capacity during treadmill exercise test on ivabradine therapy (P < 0.001). Significantly lower incidence of IST-related symptoms were registered after administration of If current inhibitor. After 2 months of treatment no patients reported severe complaints assessed by means of European Heart Rhythm Association score. We did not observe severe side effects during therapy. Ivabradine is an effective treatment option to reduce HR and symptoms in patients with IST after RF ablation of atrioventricular node slow pathway. The therapy with ivabradine is well tolerated even with maximum daily dose.

Asystole induced by radiofrequency catheter ablation of slow pathway

Radiofrequency (RF) catheter ablation is a treatment of choice widely used for a variety of supraventricular tachycardia. Transient sinus and atrioventricular (AV) node dysfunctions may occur during RF application to sites remote from the sinus and AV nodes, but they generally resolve quickly after cessation of RF current. We present a case of two episodes of asystole in a 43-year-old man induced by RF catheter ablation of an AV nodal slow pathway. A Bezold–Jarisch-like reflex, direct stimulation of parasympathetic fibers traveling to the sinus and AV nodes, RF-induced myocardial injury or pain could be responsible for this situation.

Familial Occurrence of Atrioventricular Nodal Reentrant Tachycardia in a Mother and Her Son

Atrioventricular nodal reentrant tachycardia (AVNRT), caused by a reentry circuit involving fast and slow atrioventricular nodal pathways, is one of the most common types of paroxysmal supraventricular tachycardias. While familial Wolff-Parkinson-White syndrome has been well recognized, familial AVNRT has been rarely reported. We report a familial occurrence of AVNRT in a mother and her son, who were symptomatic and successfully treated with radiofrequency catheter ablation of slow pathway.

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.

Radiofrequency catheter ablation of the slow pathway for atrioventricular nodal reentry in a patient with an obstructed inferior vena cava

A 51-year-old man with an obstructed inferior vena cava underwent successful slow pathway catheter ablation using a superior venous approach. Two central venous sheaths were introduced into the right internal jugular vein using different approaches (anterior and posterior), so the two sheaths located away from each other could prevent the catheters from 'sticking' to one another. The transseptal long sheath enabled a stable positioning of the ablation catheter. A nonfluoroscopic mapping system could reduce radiation exposure to the ablator. These techniques may be useful to overcome the disadvantages of the superior venous approach compared to the inferior venous approach.

Usefulness of Incremental Atrial Pacing for Evaluating the Effectiveness of Perinodal Slow Pathway Ablation

Introduction and objectives. To study the usefulness of incremental atrial pacing for evaluating the effect of radiofrequency catheter ablation on slow pathway conduction in patients with atrioventricular (AV) nodal reentrant tachycardia. Methods. A prospective study was carried out in patients either with (ie, AV nodal reentrant tachycardia group) or without (ie, control group) inducible AV nodal reentrant tachycardia who were referred for electrophysiologic study. Incremental atrial pacing involved gradually decreasing the pacing cycle length until the PR interval exceeded the R-R interval (ie, PR>RR) or AV nodal block occurred. The presence of dual anterograde AV nodal physiology was assessed during programmed atrial stimulation using standard criteria. In the AV nodal reentrant tachycardia group, electrophysiologic study was repeated 30 minutes after successful catheter ablation. Results. In the AV nodal reentrant tachycardia group (n=85), 52 patients (61%) exhibited dual AV nodal physiology during programmed atrial stimulation and 66 (78%) had a PR>RR during incremental atrial pacing. In the control group, the corresponding proportions were 10/56 (18%) and 7/56 (12%), respectively. After successful slow pathway catheter ablation (81/85), 37/81 exhibited dual AV nodal physiology during programmed atrial stimulation while 1/81 had a PR>RR during incremental atrial pacing. The positive predictive value of successful slow pathway ablation for the absence of a PR>RR was 98%. Conclusions. Incremental atrial pacing demonstrated that the PR interval exceeded the R-R interval in the majority of patients with inducible AV nodal reentrant tachycardia. This technique could provide a fast and simple way of evaluating the effect of radiofrequency catheter ablation on slow pathway conduction.

P5-62: Early and delayed pacemaker implantation after radiofrequency catheter ablation of slow pathway

P5-62: Early and delayed pacemaker implantation after radiofrequency catheter ablation of slow pathway

Radiofrequency Catheter Ablation Therapy of Swallowing‐Induced Atrioventricular Nodal Reentrant Tachycardia: Report of Two Cases

We describe two patients who presented with a history of recurrent palpitations on swallowing of solid food. The event-recorder and Holter monitoring documented episodic supraventricular tachycardia (SVT) initiated by atrial premature contractions (APCs). During electrophysiological study (EPS), swallowing of solid food consistently induced APCs and their activation sequence, morphology of P wave were suggestive of their right atrial origin in them. Drug challenge did not affect the APC onset during the swallowing. During EPS, slow-fast variety of atrioventricular nodal reentrant tachycardia (AVNRT) was induced and successful radiofrequency (RF) catheter ablation of slow pathway resulted in total relief of their symptoms.

Long-term efficacy of slow-pathway catheter ablation in patients with documented but noninducible supraventricular tachycardia

The long-term efficacy of radiofrequency catheter ablation of slow pathway in patients with dual atrioventricular node pathway and a documented but noninducible paroxysmal supraventricular tachycardia (PSVT) is not entirely clear. Forty nine patients (Group A) with documented but noninducible PSVT and dual atrioventricular node pathway were prospectively studied. Programmed electrical stimulation induced a single atrioventricular node echo beat in 13 patients, and double echo beats in 9 at baseline or during isoproterenol infusion. Clinical and electrophysiological characteristics of Group A patients were compared with that of age- and gender-matched patients with dual atrioventricular node pathway but inducible PSVT (Group B). There was no significant difference in the electrophysiological properties of the fast and slow pathways between the two groups. Catheter ablation eliminated the slow pathway in all patients. There was no recurrence of PSVT in either Group A or Group B during the follow-up of 38 +/- 5 months. In patients with dual atrioventricular node pathway and a documented but noninducible PSVT, catheter ablation of slow pathway is highly effective in preventing tachycardia in long term.

Long-term follow-up of patients with P-R prolongation after catheter ablation of slow pathway for atrioventricular node re-entrant tachycardia

Long-term impact of interval between P wave and R wave (P-R) prolongation on prognosis of patients with successful catheter ablation of slow atrioventricular nodal pathway was investigated. Among 436 patients undergoing slow-pathway ablation for atrioventricular node re-entrant tachycardia (AVNRT), 17 (3.9%) experienced permanent P-R prolongation. Ablation target sites where conduction block was induced were located in mid- or anteroseptum. Fast junctional rhythm with ventriculoatrial conduction block was observed in eight patients immediately before atrioventricular block. Antegrade slow-pathway conduction was eliminated in 16 patients, and retrograde fast- and slow-pathway conduction was abolished in all patients. There was no recurrence of AVNRT after an average of 38 +/- 12 month follow-up. There was no deterioration of atrioventricular block in these patients. Average PR interval prior to hospital discharge and at the end of follow-up was 0.24 +/- 0.02 sec and 0.23 +/- 0.02 sec, respectively (p >0.05). Left ventricular ejection fraction remained unchanged in these patients (p >0.05). Radiofrequency catheter ablation of slow pathway for AVNRT is associated with a small risk of atrioventricular block. PR prolongation after successful slow-pathway ablation is associated with benign prognosis.

Ablación con catéter mediante radiofrecuencia de la taquicardia por reentrada intranodal en niños y adolescentes

Radiofrequency catheter ablation of slow pathway is the primary nonpharmacological treatment for the atrioventricular node reentrant tachycardia at present. To evaluate the results and long term follow-up of the catheter and radiofrequency modification of the AV node in the treatment of the atrioventricular node reentrant tachycardia in children and adolescents in our center. In a series of fifteen patients, 7 men and 8 women, with a mean age of 8.7 +/- 5.5 years (range, from 4 to 18) with atrioventricular node reentrant tachycardia underwent radiofrequency catheter ablation. Six patients had been treated previously with 1.4 +/- 1.1 antiarrhythmic drugs and nine had not received treatment. In all patients slow-pathway atrioventricular node ablation guided by an anatomic stepwise approach was attempted. In 14 out of 15 patients slow pathway was successfully ablated; and in one patient with a previously failed slow-pathway ablation, a fast-pathway ablation was performed. Tachycardia recurred in one patient, and slow pathway was ablated in a second procedure. After successful slow pathway ablation in 14 patients, the shortest cycle length in which the AV conduction was maintained at 1:1, was increased from 271.3 +/- 22.6 to 316.7 +/- 30.1 ms (p < 0.001), while the AH and HV intervals and shortest cycle length of 1:1 VA conduction remained unchanged. In the patient who had fast pathway ablation the AH interval was increased from 65 to 130 ms, and retrograde VA conduction was lost. Noninducibility of the tachycardia was achieved in all patients without significant complications. During a mean follow-up of 18.8 +/- 11.4 months (median of 16), all patients are symptom-free without medication. Radiofrequency catheter ablation is a successful and safe therapeutic alternative in the treatment of atrioventricular node reentrant tachycardia in children and adolescents.

Clinical and Electrophysiologic Characteristics and Long-Term Efficacy of Slow-Pathway Catheter Ablation in Patients With Spontaneous Supraventricular Tachycardia and Dual Atrioventricular Node Pathways Without Inducible Tachycardia

Objectives. We sought to investigate the long-term efficacy of slow-pathway catheter ablation in patients with spontaneous, documented paroxysmal supraventricular tachycardia (PSVT) and dual atrioventricular (AV) node pathways but without inducible tachycardia.Background. The lack of reproduction of clinical PSVT by programmed electrical stimulation, which is not uncommon in AV node reentrant tachycardia (AVNRT), is a dilemma in making the decision of the therapeutic end point of radiofrequency catheter ablation.Methods. Twenty-seven patients (group A) with documented but noninducible PSVT and with dual AV node pathways were prospectively studied. Programmed electrical stimulation could induce a single AV node echo beat in 12 patients, double echo beats in 4 patients and none in 11 patients at baseline or during isoproterenol infusion. Of the patients in group A, 16 underwent slow-pathway catheter ablation and 11 did not. The clinical and electrophysiologic characteristics of the 27 patients were compared with those of patients with dual AV node pathways and inducible AVNRT (group B, n = 55) and patients with dual AV node pathways alone without clinical PSVT (group C, n = 47).Results. During 23 ± 13 months of follow-up, none of the 16 patients with slow-pathway catheter ablation had recurrence of PSVT. However, 7 of the 11 patients without ablation had PSVT recurrence at 13 ± 14 months of follow-up (p < 0.03 by Kaplan-Meier analysis). Compared with groups B and C, group A consisted predominantly of men who had better retrograde AV node conduction and a narrower zone for anterograde slow-pathway conduction.Conclusions. Slow-pathway catheter ablation is highly effective in eliminating spontaneous PSVT in which the tachycardia is not inducible despite the presence of dual AV node pathways.