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Background: The ability to differentiate right ventricular outflow tract (RVOT) from coronary cusp (CC) site of origin (SOO) by 12-lead ECG in pediatric patients may impact efficacy and procedural time. The objective of this study was to predict RVOT versus CC SOO by ECG in pediatric patients., Methods: Pediatric patients (<21 years) without structural heart disease with RVOT or CC premature ventricular contraction (PVC) ablations performed (2014-2018) were evaluated through multi-institution retrospective review. Demographics, ECG PVC parameters, ablation site, recurrence, and repeat procedures were collected., Results: Thirty-seven patients were evaluated (mean age 14.6 years, weight 60.6 kg): 11 CC and 26 RVOT PVC SOO. CC PVCs were less likely to exhibit left bundle branch block (64% vs 100%, P = .005), had larger R-wave amplitude in V1 (0.27 vs 0.11 mV, P = .03), larger R/S ratio in V1 (0.37 vs 0.09, P = .003), and had precordial transition in V3 or earlier (73% vs 15%, P = .002). A composite score was created with the following variables: isodiphasic or positive QRS in V1, R/S ratio in V1 > 0.05, S wave in V1 < 0.9 mV, and precordial transition at or before V3. Composite score ≥ 2 was associated with a CC SOO (OR 42.0, P = .001, and AUC 0.86)., Conclusions: 12-lead ECG of PVCs from the CC was associated with larger V1 R-wave amplitude, larger R/S ratio in V1, and precordial transition at or before V3. A composite score may help predict PVC/VT arising from the CC., (© 2020 Wiley Periodicals, Inc.)

Background: Axillary venous access with ultrasound guidance for pediatric transvenous lead implantation may reduce risks for pneumothorax and hemothorax. The objective was to retrospectively evaluate ultrasound-guided axillary vein access as an alternative to the subclavian approach., Methods: The technique consists of ultrasonographic identification of the axillary vein at the deltopectoral groove after initial contrast venography. A micropuncture kit is used for initial ultrasound-guided percutaneous access with fluoroscopic confirmation of wire position. Pocket creation is performed, and sheath insertion and lead implantation proceed as usual. Demographic, procedural, and radiation exposure data were collected and analyzed., Results: Sixteen patients (median age = 13 years, 8-50 years; median weight = 56 kg, 29-77 kg) underwent lead implantation; two additional patients required fluoroscopy due to poor acoustic windows (89% success). Fifteen of 21 leads (71%) were ventricular; 50% of implants were pacemakers, and 31% were dual chamber. Median time to venous access was 13 min (interquartile range (IQR) = 9.25-20.25) and median implant procedure time was 156 min (IQR = 112-172). Median fluoroscopy time was 18.0 min (IQR = 11.9-29.6), median air kerma was 9.0 mGy (IQR = 3.0-28.5), and median dose-area product was 30.2 Gy-cm 2 (IQR = 16.1-234.5). One patient required generator pocket revision 2 days postprocedure without lead dislodgement. There were no other complications encountered., Conclusions: Transvenous pacemaker and implantable cardioverter-defibrillator lead implantation in the pediatric and adult congenital population through ultrasound-guided axillary venous access is safe and efficacious. This technique may provide a low-risk alternative for vascular access for pediatric implantation procedures., (© 2018 Wiley Periodicals, Inc.)

Background: Concealed left-sided accessory pathways (CLAP) are a cause of supraventricular tachycardia (SVT) in the young. Most are mapped with right ventricular (RV) apical/outflow pacing. Rarely, alternative means of mapping are required. We review our experience from three pediatric electrophysiology (EP) centers with a rare form of "hidden" CLAP., Methods: All patients <21 years undergoing EP study from 2008 to 2014 with a "hidden" CLAP (defined as an accessory pathway [AP] for which RV pacing at cycle lengths [CL] stable for mapping did not demonstrate eccentric retrograde conduction) were included., Exclusion Criteria: preexcitation. Demographic, procedural, and follow-up data were collected., Results: A total of 23 patients met the criteria (median age, 14.3 years [range 7-21], weight, 51 kg [31-99]). 21 (96%) had SVT and one AFIB (4%). APs were adenosine sensitive in 7/20 patients (35%) and VA conduction was decremental in six (26%). CLAP conduction was demonstrable with orthodromic reentrant tachycardia in all patients, with RV extrastimulus testing in seven (30%) and with rapid RV pacing (

Background: Ablation within the aortic cusp is safe and effective in adults. There are little data on aortic cusp ablation in the pediatric literature. We investigated the safety and efficacy of aortic cusp ablation in young patients., Methods: A retrospective, descriptive study of aortic cusp ablation in five pediatric electrophysiology centers from 2008 to 2014 was performed. All patients <21 years of age who underwent ablation in the aortic cusps were included. Factors analyzed included patient demographics, procedural details, outcomes, and complications., Results: Thirteen patients met inclusion criteria (median age 16 years [range 10-20.5] and median body surface area 1.58 m 2 [range 1.12-2.33]). Substrates for ablation included: nine premature ventricular contractions or sustained ventricular tachycardia (69%), two concealed anteroseptal accessory pathways (APs) (15%), one Wolff-Parkinson-White with an anteroseptal AP (8%), and one ectopic atrial tachycardia (8%). Three-dimensional electroanatomic mapping in combination with fluoroscopy was used in 12/13 (92%) patients. Standard 4-mm-tip radiofrequency (RF) current was used in 11/13 (85%) and low-power irrigated-tip RF in 2/13 (15%). Angiography was used in 13/13 and intracardiac echocardiography was additionally utilized in 3/13 (23%). Ablation locations included: eight noncoronary (62%), three left (23%), and two right (15%) cusps. Ablation was acutely successful in all patients. At median follow-up of 20 months, there was one recurrence of PVCs (8%). There were no ablation-related complications and no valvular injuries observed., Conclusion: Arrhythmias originating from the coronary cusps in this series were successfully and safely ablated in young people without injury to the coronary arteries or the aortic valve., (© 2017 Wiley Periodicals, Inc.)

Background: CARTO3 is frequently used during ablation but is not designed to allow visualization of non-CARTO3 ablation catheters. We describe how cryoablation catheters can be visualized and recorded using CARTO3 with minimal fluoroscopy (FLUORO) usage., Methods: Retrospective review of patients ≤21 years undergoing cryoablation with CARTO3 from 2010 to 2013 for ablation of supraventricular tachycardia. After mapping with a Navistar catheter, the Navistar was removed and a cryocatheter was utilized. The cryocatheter was connected to the pin box via a jumper cable and the pin box was connected to the CARTO3 patient interface unit. Locations of ablation attempts with the cryocatheter were recorded with the "Create Snapshot" tool. Clinical characteristics and radiation doses were compared between patients undergoing cryoablation (cryoenergy [CRYO]) to an age- and diagnosis-matched control group (CONTROL) undergoing RF ablation., Results: A total of 174 ablations were performed and 14 patients underwent cryoablation (CRYO, 13.3 ± 4.7 years, weight 42 ± 14 kg). Indications for cryoablation were: five atrioventricular nodal reentry tachycardia (36%), four ectopic atrial tachycardia (29%), three concealed accessory pathways (21%), and two Wolff-Parkinson-White syndromes (14%). Acute success was achieved in all patients (100%) with no complications and one recurrence (7%). The site of successful cryoablation was successfully recorded on the CARTO3 system in all cases. Radiation doses were low and not different from an age-, era-, and diagnosis-matched control group undergoing RF ablation (CRYO 3.2 ± 0.8 mGy vs CONTROL 1.6 ± 0.4 mGy, P = 0.07)., Conclusions: Though a "closed" system, CARTO3 can be "tricked" to allow for the use of cryoablation, allowing clear catheter visualization, mapping, and recording of ablation lesions with minimal FLUORO usage., (©2015 Wiley Periodicals, Inc.)

Purpose: To compare the efficacy, safety, and cost-effectiveness of a three-catheter approach with a conventional five-catheter approach for the mapping and ablation of supraventricular tachycardia in pediatric patients with Wolff-Parkinson-White Syndrome (WPW) and concealed accessory pathways (APs)., Methods: A retrospective review from 2008 to 2012 of patients less than 21 years with WPW who underwent a three-catheter radiofrequency (RF) ablation of a left-sided AP (ablation, right ventricular [RV] apical, and coronary sinus [CS] decapolar catheters) was performed. The three-catheter group was compared to a control group who underwent a standard five-catheter (ablation, RV apical, CS decapolar, His catheter, and right atrial catheter) ablation for the treatment of left-sided WPW or concealed AP. Demographics, ablation outcomes, and costs were compared between groups., Results: Twenty-eight patients met inclusion criteria with 28 control patients. The groups did not differ in gender, age, weight, or body surface area. Locations of the AP on the mitral annulus were similar between the groups. All patients were ablated via transseptal approach. Note that 28 of 28 in the three-catheter group (100%) and 27 of 28 (96%) controls were acutely successfully ablated (P = 0.31). No complications were encountered. There was no difference in procedural time, time to loss of AP conduction, or number of RF applications. Use of the three-catheter technique resulted in a total savings of $2,465/case, which includes the $680 savings from using fewer catheters as well as the savings from a shortened procedure time., Conclusions: Ablation in patients with WPW and a left-sided AP can be performed using three catheters with similar efficacy and safety while offering significant cost savings compared to a conventional five-catheter approach., (© 2015 Wiley Periodicals, Inc.)

Introduction: There are little data on the effect of catheter position and mechanical ventilation on ablation catheter stability during electrophysiology study in children. We sought to determine the magnitude of catheter movement with mechanical ventilation, the effect of ventilation maneuvers on catheter movement, and to compare the degree of movement observed between the right lateral (RL) and right posteroseptal (RPS) regions., Methods: From June 2012 to June 2013, patients ≤ 21 years of age undergoing ablation for supraventricular tachycardia with CARTO® 3 (Biosense Webster, Diamond Bar, CA, USA) were included. During mapping the ablation catheter was placed in the RPS and RL regions and the magnitude of catheter movement (mm) was measured using CARTO® 3. Measurements were made during routine ventilation and with a maximal inspiration maneuver between end-expiration (ENDEX) and peak-inspiration (PEAKINS)., Results: Twenty-one patients were included: 12 males (57%), age 13 ± 3 years, weight 55 ± 14 kg. Indications for ablation were: 10 Wolff-Parkinson-White, seven atrioventricular node re-entry tachycardia, four concealed accessory pathway. Mechanical ventilation was used in all cases. The magnitude of catheter movement was 3.6 ± 1.7 mm with routine ventilation and 6.2 ± 4.1 mm between ENDEX and PEAKINS (P ≤ 0.01). Catheter movement was greater in the RL compared to the RPS region with routine ventilation (RL 4.3 ± 1.6 vs RPS 3.0 ± 1.5; P < 0.01) and between ENDEX and PEAKINS (RL 8.3 ± 4.7 vs RPS 4.0 ± 1.7; P < 0.01)., Conclusions: Ventilation and catheter position both have significant impact on the degree of catheter movement during ablation. Movement was greatest in the RL position. This may partially explain the lower success rates of ablation in the RL region., (©2014 Wiley Periodicals, Inc.)

Background: Ablation for supraventricular tachycardia (SVT) relies upon fluoroscopy (fluoro), which exposes the patient and staff to ionizing radiation. The objective of this work was to present a new "ALARA--As Low As Reasonably Achievable" protocol with alterations to fluoroscopic x-ray parameters to reduce dose without an electroanatomical (EAM) approach., Methods: All patients <21 years of age undergoing ablation of SVT at our institution from June 2011 to April 2012 were included. EAM was not utilized in any case. An ALARA protocol of low frame rates (2 or 3 fps), low fluoro dose/frame (10-18 nGy/frame), and other techniques aimed at reducing use of fluoroscopy were employed. Demographics, procedural, and radiation data were analyzed., Results: Forty-two patients underwent ablation and were studied. Median age was 14.1 years (range 4.8-21.1 years), weight was 51 kg (range 18.2-75 kg), and body surface area was 1.51 m(2) (range 0.72- 1.94 m(2)). Seventeen (41%) had Wolff-Parkinson-White syndrome, 14 (33%) atrioventricular nodal reentrant tachycardia, and 11 (26%) concealed pathways. Median procedural time was 114 minutes (57-246 minutes). Median dose area product (DAP) for posterioanterior and lateral fluoroscopy was 343.2 uGym(2) (range 38.2-3,172 uGym(2)); the median air Kerma product (K) was 45.4 mGy (range 6.7-567.5 mGy). DAP and K are lower than prior data from EAM and fluoroscopy techniques. The acute success rate was 95%; no procedural complications., Conclusions: An ALARA protocol for ablation of SVT reduced radiation to below levels previously reported for combined EAM/fluoro approaches. Success rates were excellent with no complications and without the costs of EAM., (©2013, The Authors. Journal compilation ©2013 Wiley Periodicals, Inc.)

Background: Antidromic reciprocating tachycardia (ART) is a rare form of wide complex tachycardia in children with Wolff-Parkinson-White syndrome (WPW). The incidence and electrophysiologic characteristics of ART in children with WPW have not been well described., Methods: A multicenter retrospective analysis of all patients with WPW undergoing electrophysiology (EP) study from 1990 to 2009 was performed. Patients with clinical or inducible ART were included., Results: A total of 1,147 patients with WPW underwent EP study and 30 patients had ART (2.6%) and were the subject of this analysis. The mean age was 16±3 years, weight was 65±16 kg, and tachycardia cycle length was 305±55 ms. There were two patients (7%) with congenital heart disease (both with Ebstein's anomaly). Four patients (13%) had more than one accessory pathway (AP). The location of the AP was left sided in 53% of patients and right sided in 47%, with septal location and left lateral pathways most commonly involved. AP conduction was found to be high risk in 17 patients (57%). Ablation was not attempted in two patients (7%) due to proximity to the HIS and risk of heart block. Ablation was acutely successful in 93% of the patients in whom it was attempted., Conclusions: ART is a rare finding in children undergoing EP study. Over half of the patients with ART were found to be high risk and multiple AP were uncommon. Unlike the adult population, ART occurred commonly with septal APs., (©2012, The Authors. Journal compilation ©2012 Wiley Periodicals, Inc.)

Background: Electrocardiograms (ECGs) are sent via facsimile by pediatricians and psychiatrists to cardiologists for assessment. The validity of this method of transmission has not been established., Methods:  ECGs were collected from 100 consecutive patients from the cardiology clinic of the Children's Hospital at Montefiore. The ECGs were faxed and also electronically faxed (efax) and printed. Two electrophysiologists (EP1 and EP2) interpreted the intervals on original, faxed, and efaxed ECGs and intervals (RR, PR, and QT) were compared. A three-way analysis of variance to examine differences between raters, among ECG intervals, and among methods (repeated factor) was performed. Because no interaction terms were significant, a Duncan's multiple range test was used to evaluate where differences occurred among the three intervals and three methods, given these main effects were significant., Results:  The difference between raters EP1 and EP2 was not significant (P = 0.6681). Although the interval measurements of the faxed and efaxed ECGs were not significantly different from each other (P > 0.05), each was significantly different from the original across all three ECG intervals and both raters (P = 0.0138). The RR interval yielded mean (SD) values for the original, faxed, and efaxed methods of 0.6986 seconds (0.2074), 0.6646 seconds (0.1938), and 0.6838 seconds (0.1935), respectively. For the QT interval, the mean (SD) values for the original, faxed, and efaxed methods were 0.3370 seconds (0.0524), 0.32134 seconds (0.0466), and 0.3284 seconds (0.0515), respectively., Conclusions:  ECG transmission via facsimile or efax may introduce significant distortion of the intervals. Alternative means of sending ECGs for interpretation should be considered., (©2011, The Authors. Journal compilation ©2011 Wiley Periodicals, Inc.)

We present the case of an 11-year-old with D-transposition, double inlet left ventricle, and dextrocardia 8 years following an extracardiac Fontan with supraventricular tachycardia mediated by a concealed accessory pathway. A transbaffle puncture was performed with fluoroscopic and transesophageal echocardiography guidance and the pathway location as well as its proximity to the HIS bundle were identified. The pathway was successfully ablated and the patient is asymptomatic for 12 months postablation.

Background: In adults, transvenous implantable cardioverter defibrillator (ICD) lead failure rates are significant, and their occurrence increases with time from implant. There are limited data in children. The goal of this study was to assess lead survival in young patients undergoing ICD implantation at a single center., Methods: Records of patients under 21 years old with transvenous ICD leads implanted at our center from June 1997 to August 2007 were retrospectively reviewed. Age, weight, height, diagnosis, lead and generator model, venous access technique, generator position, pacing thresholds, lead impedance, and R wave size were recorded. "Lead failure" was defined as any lead problem requiring surgical intervention to restore proper function to the ICD system., Results: Seventy-one transvenous leads were included (70 patients). Average age at implant was 14.8 years (range 5.7-19.5). All the devices were implanted by a single operator (HMS). Venous access was obtained via cephalic cutdown in 66/71. Mean follow-up time was 2.8 years (range 0.2-7.8 years, median 2.3 years). There were no infections requiring explantation. There were four lead failures. Three were lead fractures, occurring 12, 13, and 19 months after implant. The fourth lead failed when an arrhythmia was not appropriately detected, and a second dedicated rate-sensing lead was thus implanted. Univariate analysis did not identify any variable to be a significant predictor of lead failure. Kaplan-Meier survival analysis demonstrated 5-year lead survival at 89.6%., Conclusions: ICD lead survival in children, when performed by an experienced operator, is similar to that found in adults.

Background: Syncope due to episodes of paroxysmal atrioventricular (AV) block, defined as transient advanced second or third-degree block, is rarely reported in pediatric patients without congenital heart disease., Methods: We reviewed our institutional arrhythmia database from January 1988 to January 2007 to identify all patients less than 18 years of age with normal cardiac anatomy and episodes of syncope associated with paroxysmal AV block. Demographic and clinical information was collected., Results: Six patients were identified (Table I). Five of the six patients were female, with an average age of 9.3 +/- 4.4 years. Patients had episodes of syncope for an average of 5.6 +/- 3.3 years prior to diagnosis. All patients had normal physical examinations, electrocardiograms, and echocardiograms. None were on medications known to interfere with AV nodal function, and laboratory evaluation including Lyme titers were negative. Five of the six patients' episodes were atypical for vasovagal syncope (except patient 6). All patients had documented paroxysmal AV block on either inpatient cardiac monitor, Holter monitor, or event recorder at the time of syncope. There was maintenance or acceleration of the sinus rate during episodes of syncope in all patients (mean atrial rate 107 +/- 37 bpm). All six patients had permanent transvenous pacemakers implanted with resolution of symptoms over a mean follow-up of 5.2 +/- 6.3 years., Conclusion: Paroxysmal AV nodal block is a rare finding in pediatric patients, but should be considered as a possible etiology in patients presenting with episodes atypical for vasovagal syncope. Pacemaker therapy prevented future episodes in all six of our patients.

Background: 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., Objective: 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., Methods: 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., Results: 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%)., Conclusion: Rapid atrial pacing during radiofrequency catheter ablation of the slow pathway is a safe alternative approach to ensure normal AVN function.

Background: Low-dose biphasic waveform cardioversion has been used for the termination of atrial arrhythmias in adult patients. The energy required for termination of atrial arrhythmias in pediatric patients is not known. The objective of this study is to determine the minimum energy required for successful external cardioversion of atrial arrhythmias in pediatric patients using biphasic waveform current., Methods: Prospective study of all patients less than 24 years of age with and without congenital heart disease undergoing synchronized cardioversion for atrial arrhythmias. Patients were assigned to receive an initial biphasic energy shock of 0.2-0.5 J/kg and if unsuccessful in terminating the arrhythmia, subsequent sequential shocks of 1 and 2 J/kg would be administered until cardioversion was achieved. The end point of the cardioversion protocol was successful cardioversion or delivery of three shocks., Results: Between June 2005 and June 2006, 16 patients underwent biphasic cardioversion for atrial flutter or fibrillation. The mean age was 14.7 +/- 6.4 years (range: 2 weeks to 24 years). The mean weight was 51 +/- 21 kg (range: 3.8-82 kg). Seven patients had normal cardiac anatomy, three had a single ventricle (Fontan), two had a Senning operation; the remaining four patients had varied forms of congenital heart disease. The median length of time that the patients were in tachycardia was 12 hours (range: 5 minutes to 2 months). Using either transthoracic echocardiography (TTE) or transesophageal echocardiography (TEE), no thrombi were identified in any patient. All patients were successfully cardioverted with biphasic waveform energy. The successful energy shock was 0.35 +/- 0.19 J/kg (range: 0.2-0.9 J/kg). All but one patient were successfully cardioverted with less than 0.5 J/kg. The transthoracic impedance range was between 41 and 144 Omega; one patient had an impedance of 506 Omega (2-week-old infant with a weight of 3.8 kg). The mean current delivered was 5.4 +/- 2.2 A (range: 1-11 A)., Conclusion: Low-dose energy using biphasic waveform shocks can be used for successful termination of atrial arrhythmias in pediatric patients with and without congenital heart disease.

Isoproterenol (ISO) testing following radiofrequency catheter ablation (RFCA) of accessory pathways (APs) in children is often performed to assess efficacy. However, its role in postablative testing for this indication has not been previously studied. In view of a recent national shortage of ISO, this study reviewed the results of ISO testing in pediatric patients after acutely successful RFCA to evaluate its role in postablative testing. Seventy patients (median age 13.0 years, range 2.8-24 years) underwent acutely successful RFCA for APs. If AP conduction was not present and tachycardia was not inducible with programmed stimulation 30 minutes following RFCA, repeat testing was performed during continuous infusion ISO. ISO infusion resulted in the induction of arrhythmias in 3 (4%) of 70 patients that required further ablative therapy. None of these patients had inducible arrhythmias or AP conduction during postablative testing without ISO infusion. One patient, with the permanent form of junctional reciprocating tachycardia (PJRT), had persistence of AP conduction requiring further RFCA applications. Two patients had inducible AV nodal reentrant tachycardia (AVNRT) that was treated with slow pathway modification. At a median follow-up of 7.3 months, two (3%) patients had recurrence of tachycardia. These patients did not have inducible tachycardia, AP conduction, or dual AVN physiology with ISO testing. Although ISO may improve AP conduction in patients with PJRT and uncover AVNRT, these results suggest that ISO testing after an apparently successful AP ablation may not be necessary to confirm acute success. In addition, lack of AP conduction on ISO did not rule out the possibility of medium-term recurrence.

Supraventricular tachyarrhythmias following the Fontan procedure can be life-threatening. Though most are commonly due to intraatrial reentry, orthodromic reentrant tachycardia may also be present. Atrioventricular accessory pathways may develop across suture lines following right atrial to right ventricular anastomosis in patients with tricuspid atresia. We report a case of a patient who underwent this type of Fontan who developed orthodromic reentrant tachycardia and heart failure. An electrophysiological study revealed the presence of an atrioventricular accessory pathway traversing the Fontan anastomosis suture line. Successful radiofrequency ablation of the accessory pathway led to control of the tachyarrhythmia and improvement of heart failure.