Radiofrequency catheter ablation of idiopathic ventricular tachycardias in children

Effectiveness of Radiofrequency Catheter Ablation of Outflow Tract Ventricular Arrhythmias in Children and Adolescents

Outflow tract ventricular arrhythmias (OTVAs) are common in children; however, experience is limited on their radiofrequency catheter ablation (RFCA). The purpose of this study was to assess the outcomes of mapping and ablation of pediatric OTVAs and to evaluate the role of ECG algorithms in distinguishing the origin of OTVAs. We compared retrospectively collected single-center data on 92 consecutive pediatric patients (58 male; age, 8.2 ± 2.9 [range 3.6-18] years) who underwent RFCA for OTVAs from 2009 to 2015. Two independent and blinded observers analyzed ECG data. Of these children, 69 (75 %) were of RVOT origin. RFCA was given up in 1 case, and the acute success rate was 92.3 % (84/91), the 1-year follow-up recurrence rate was 8.3 % (7/84) and the complications of the procedure were 2.2 % (2/92). And 3D versus 2D mapping-guided RFCA was associated with significantly (p < 0.05) higher acute success rate (96.1 % [49/51] vs. 87.5 % [35/40]), and lower X-ray exposure (742.5 ± 323.1 vs. 1432.3 ± 605.5 mGy cm²) and 1-year recurrence rate (4.1 % [2/49] vs. 14.3 % [5/35]). The positive predictive value of four types of ECG algorithms used in adults for LVOT origin was only 47.7-65.4 %. In these cases, four identified as RVOT origin and two identified as LVOT origin by ECG underwent successful ablation on the other side of outflow tract finally. And these six children who underwent successful RFCA in both sides of outflow tract had no follow-up recurrence. OTVAs in children originate mostly from RVOT. RFCA can be used for ablation of pediatric OTVAs effectively and safely. In some cases, successful RFCA should be ablated in both sides of outflow tract. ECG-based prediction of OTVA origin as used in adults is limited in children.

Catheter ablation of idiopathic right ventricular arrhythmias in children with limited fluoroscopy

INTRODUCTION

Definitive therapy of idiopathic right ventricular arrhythmias (VA) remains a challenge in interventional electrophysiology. The aim of this study was to evaluate the utility of EnSite Velocity system in the catheter ablation of RV tachycardia in children.

METHODS

Thirty-five children with idiopathic right VA underwent catheter ablation procedure using the EnSite Velocity system guidance.

RESULTS

The mean patient age was 12.0 ± 3.7 years and the mean patient weight was 43.6 ± 18.7 kg. The origin of right VA was divided into right ventricular outflow tract (RVOT) (30 patients) and other right ventricular localizations (five patients). The mean procedure and fluoroscopy times were 175 ± 67 min and 2.35 ± 1.89 min, respectively. No fluoroscopy was used in 19 patients. Acute success was achieved in 29 patients (83 %). The focus of VA was epicardial in three failed procedures. Cryocatheter (6-mm or 8-mm tip) was used in six patients, radiofrequency ablation (RFA) (4-mm or 8-mm tip) in 26 patients, and 4-mm tip irrigated RFA in three patients. During a mean follow-up of 15.9 ± 7.1 months, ventricular tachycardia recurred in six patients (20 %). There were three complications (transient atrioventricular block developed in one patient during parahissian cryoablation and two patients developed transient complete right bundle branch block).

CONCLUSIONS

Catheter ablation of idiopathic right VA in children can be performed safely and effectively with limited fluoroscopy using the EnSite Velocity system.

Operative techniques in association with arrhythmia surgery in patients with congenital heart disease

Arrhythmia surgery in patients with congenital disease is challenged by the range of anatomic variants, arrhythmia types, and intramyocardial scar location. Experimental and clinical studies have elucidated the mechanisms of arrhythmias for accessory connections, atrial fibrillation, atrial reentry tachycardia, nodal reentry tachycardia, focal or automatic atrial tachycardia, and ventricular tachycardia. The surgical and transcatheter possibilities are numerous, and the congenital heart surgeon should have a comprehensive understanding of all arrhythmia types and potential methods of ablation. The purpose of this article is to introduce resternotomy techniques for safe mediastinal reentry and to review operative techniques of arrhythmia surgery in association with congenital heart disease.

Resolution of tachycardia-induced cardiomyopathy following ablation of verapamil-sensitive idiopathic left ventricular tachycardia

Few reports have described tachycardia-induced cardiomyopathy secondary to ventricular tachycardia. We present a 12-year-old boy with dilated cardiomyopathy and incessant verapamil-sensitive idiopathic left ventricular tachycardia. Twelve-lead electrocardiogram showed right bundle branch block QRS morphology with superior axis during tachycardia. Electrophysiology study confirmed the diagnosis, and radiofrequency ablation was done and successfully terminated and prevented induction of ventricular tachycardia. During the follow-up period of 18 months, the patient remained free of symptoms and arrhythmia. Three months after ablation, left ventricular ejection fraction improved and cardiac silhouette became normal on chest x-ray.

Radiofrequency catheter ablation of coexistent idiopathic left ventricular tachycardia and atrioventricular nodal reentrant tachycardia

A healthy 15-year-old male patient presented with a 6-month history of recurrent attacks of palpitations. On multiple emergency room visits, a sustained wide QRS complex tachycardia with a right bundle branch block and northwest axis deviation was documented. The tachycardia was not terminated by intravenous adenosine, but was suppressed with intravenous verapamil. There was no evidence of structural heart disease, myocarditis, long QT syndrome, or electrolyte imbalance after a series of standard examinations. Idiopathic left ventricular tachycardia (ILVT) was suspected. Electrophysiologic studies revealed 2 inducible tachycardias, which were shown to represent atrioventricular nodal reentrant tachycardia (AVNRT) and ILVT. Transformation from AVNRT to ILVT occurred spontaneously following atrial pacing. Successful ablation of ILVT and the slow atrioventricular nodal pathway resulted in cure of the double tachycardia.

Radiofrequency catheter ablation of ventricular tachycardia in children and young adults with congenital heart disease

OBJECTIVES

The aim of this study was to expand data on outcomes for radiofrequency catheter ablation (RFCA) of ventricular tachycardia (VT) in young patients and to identify obstacles to success.

BACKGROUND

Ablation of VT is performed infrequently in young patients. Published experience has been limited to case reports and small descriptive series.

METHODS

A retrospective review of 97 consecutive VT ablation procedures involving 62 patients at a single institution from 1990 to 2003 was undertaken. All intention-to-treat procedures were analyzed.

RESULTS

Mean age was 13.9 +/- 9.4 years. Procedures were categorized according to VT mechanism as follows: idiopathic right ventricle (n = 37); idiopathic left ventricle (n = 24); congenital heart disease (n = 20); or other structural disease (n = 16). Acute success was achieved in 58 (60%) of 97 procedures. Of the 39 failures, 33 were aborted cases due to inability to induce sufficient ectopy for mapping in 12, high-risk location near the His bundle or coronary artery in 11, unstable VT in 7, and anatomic obstacles in 3. Recurrence rate after acutely successful RFCA was 34% (20/58 procedures) at a mean follow-up of 3.8 +/- 2.0 years. Ultimately, long-term success was achieved in 38 (61%) of 62 patients after a mean of 1.6 +/- 0.9 procedures, with the highest success rate (87%) for idiopathic left ventricular tachycardia.

CONCLUSIONS

When analyzed on a strict intention-to-treat basis, a long-term success rate of 61% is observed with ablation of VT in young patients. Inability to induce stable VT for precision mapping and certain high-risk VT locations can be significant obstacles to success.

Beyond Fontan conversion: Surgical therapy of arrhythmias including patients with associated complex congenital heart disease

BACKGROUND

Arrhythmia operations may be extended to patients with failed ablation procedures or associated structural defects requiring surgical intervention. The purpose of this study is to review our experience with arrhythmia operations in 29 patients who did not have Fontan conversions after the introduction of catheter ablation.

METHODS

Between July 1992 and January 2002, 29 patients had operations for refractory atrial (n = 24) or ventricular (n = 5) arrhythmias. Mechanisms of arrhythmia included atrial reentry (n = 11), atrial fibrillation (n = 5), automatic atrial (n = 3), accessory connections (n = 6), atrioventricular nodal reentry (n = 2), and ventricular tachycardia (n = 5). Median age at operation was 12.3 years (range, 6 days to 45 years). Two patients had structurally normal hearts; the remaining 27 patients underwent concomitant repair of structural heart disease, including atrioventricular valve replacement or repair (n = 8), anatomy-specific repair of Ebstein's anomaly (n = 4), tetralogy of Fallot repair or revision (n = 4), atrial septal defect closure (n = 3), ventricular septal defect repair (n = 2), Mustard takedown with arterial switch (n = 2), initial Fontan (n = 2), right ventricle-to-pulmonary artery conduit revision (n = 2), Norwood procedure (n = 1), 1 ventricular repair for Uhl's anomaly (n = 1), Mustard baffle revision (n = 1), pulmonary valve replacement with aneurysm resection (n = 1), and aortic valve replacement with complex repair (n = 1).

RESULTS

No patient developed heart block, and the surgical mortality rate was 7%. One patient died after Mustard takedown and arterial switch operation, and 1 neonate died after repair of severe Ebstein's anomaly. There was one late death after arterial switch conversion at another institution. Recurrent clinical supraventricular tachycardia was present in 2 patients (2 of 27, 7.4%) and 2 patients had new-onset tachycardias with different underlying mechanisms of arrhythmia at late follow-up (median follow-up 47 months).

CONCLUSIONS

Successful surgical therapy of arrhythmias can be performed safely at the time of repair of complex congenital heart disease or in patients with failed catheter ablation procedures. Early consideration for single-stage therapy of arrhythmia and structural heart disease is indicated.

Idiopathic sustained left ventricular tachycardia in pediatric patients

BACKGROUND

Idiopathic sustained ventricular tachycardia originating from the left ventricle (ILVT) has been an indication for catheter ablation. The present study evaluated the clinical features, long-term prognosis and indications for treatment in pediatric patients with ILVT.

METHODS

The subjects of the present study were eight patients (four males and four females) with a mean age at onset of 11.0 years (range 3-15 years). The mean follow-up period was 7.7 years (range 2.1-11.3 years).

RESULTS

In electrophysiologic studies, intravenously administered verapamil was effective for the termination of tachycardia in all six patients who received this treatment and for the prevention of tachycardia in four of five patients. Oral administration of verapamil was effective in five of seven patients. Propranolol or flecainide was added to the treatment protocol for two patients who did not respond to verapamil alone. Tachycardia disappeared without drugs in four patients during the follow-up period and became non-sustained in another patient. Two of three patients with persistent tachycardia underwent catheter ablation. Pharmacologic treatment was very effective for ILVT among these patients.

CONCLUSIONS

Pharmacologic therapy, such as with verapamil, is still the treatment of choice for ILVT because of a good long-term prognosis and potential risks and complications by manipulation of catheter ablation.

Therapeutic decision tree for patients with sustained ventricular tachyarrhythmias or aborted cardiac arrest: a critical review of the Antiarrhythmics Versus Implantable Defibrillator trial and the Canadian Implantable Defibrillator Study

Antiarrhythmic drugs, mainly amiodarone and sotalol, radiofrequency catheter ablation, and the implantable cardioverter defibrillator (ICD) are the 3 therapeutic options in patients with sustained ventricular tachycardia (VT) or ventricular fibrillation (VF). Idiopathic VT, incessant VT, frequently recurring, hemodynamically stable VT, and VT based on bundle branch reentry, are candidates for radiofrequency catheter ablation. Patients with high-risk ventricular tachyarrhythmias should receive ICDs as initial therapy. Two studies, the Antiarrhythmics Versus Implantable Defibrillator trial (AVID) and the Canadian Implantable Defibrillator Study (CIDS) have tried to approach the problem of these high-risk ventricular tachyarrhythmias. Although at 3 years, the ICD in AVID demonstrated a significant relative risk reduction over amiodarone of 31.5%, CIDS could not duplicate this finding. At 3 years, the relative risk reduction conferred by the ICD over amiodarone in CIDS was only 13.7%. A careful analysis of both studies suggests that CIDS was insufficiently powered to demonstrate statistically significant benefits similar to those shown by AVID, and furthermore, seemed to include an undetermined number of low-risk VT patients. The problem in the CIDS trial in this regard was the recruitment of patients in whom the inclusion criteria were met by the arrhythmias induced during the electrophysiology stimulation study, but which did not exist in real life. In addition CIDS included 14% of patients with (1) undocumented syncope and inducible monomorphic sustained VT; or (2) long runs of spontaneous nonsustained VT. Under these circumstances, the therapeutic implications of AVID remain unchallenged.