Loss of ventricular preexcitation during noninvasive testing does not exclude high-risk accessory pathways: A multicenter study of WPW in children.

BACKGROUND: Abrupt loss of ventricular preexcitation on noninvasive evaluation, or nonpersistent preexcitation, in Wolff-Parkinson-White syndrome (WPW) is thought to indicate a low risk of life-threatening events. OBJECTIVE: The purpose of this study was to compare accessory pathway (AP) characteristics and occurrences of sudden cardiac arrest (SCA) and rapidly conducted preexcited atrial fibrillation (RC-AF) in patients with nonpersistent and persistent preexcitation. METHODS: Patients 21 years or younger with WPW and invasive electrophysiology study (EPS) data, SCA, or RC-AF were identified from multicenter databases. Nonpersistent preexcitation was defined as absence/sudden loss of preexcitation on electrocardiogram, Holter monitoring, or exercise stress test. RC-AF was defined as clinical preexcited atrial fibrillation with shortest preexcited R-R interval (SPERRI) ≤ 250 ms. AP effective refractory period (APERP), SPERRI at EPS , and shortest preexcited paced cycle length (SPPCL) were collected. High-risk APs were defined as APERP, SPERRI, or SPPCL ≤ 250 ms. RESULTS: Of 1589 patients, 244 (15%) had nonpersistent preexcitation and 1345 (85%) had persistent preexcitation. There were no differences in sex (58% vs 60% male; P=.49) or age (13.3±3.6 years vs 13.1±3.9 years; P=.43) between groups. Although APERP (344±76 ms vs 312±61 ms; P<.001) and SPPCL (394±123 ms vs 317±82 ms; P<.001) were longer in nonpersistent vs persistent preexcitation, there was no difference in SPERRI at EPS (331±71 ms vs 316±73 ms; P=.15). Nonpersistent preexcitation was associated with fewer high-risk APs (13% vs 23%; P<.001) than persistent preexcitation. Of 61 patients with SCA or RC-AF, 6 (10%) had nonpersistent preexcitation (3 SCA, 3 RC-AF). CONCLUSION: Nonpersistent preexcitation was associated with fewer high-risk APs, though it did not exclude the risk of SCA or RC-AF in children with WPW.

A multicenter review of ablation in the aortic cusps in young people.

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 m2 [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.

Defibrillation Testing Strategies of Pediatric and Adult Congenital Electrophysiologists during ICD Implantation.

BACKGROUND: Recently, there has been an increasing number of internal medicine-trained electrophysiologists who choose not to test for acute defibrillation efficacy during implantable cardioverter defibrillator (ICD) implantation. It is not known whether this same trend is seen in pediatric electrophysiologists, who care primarily for patients with congenital heart disease or primary electrical problems. METHODS: Through a 14-question survey created on Survey Monkey, we asked the members of the Pediatric and Adult Congenital Electrophysiology Society (PACES) for their approach to ICD implantation. In particular, respondents were asked for their individual practice preferences on testing for acute defibrillation efficacy, including methods used for testing. RESULTS: There were 108 survey respondents. Thirty-nine percent test acute defibrillation efficacy at all implants, while 46% test in most patients, barring any clinical concerns. Another 14% routinely test during initial ICD system implants but not during generator changes with existing leads. Less than 1% of respondents do not routinely test acute defibrillation efficacy. CONCLUSIONS: The practice preferences of pediatric electrophysiologists in evaluating for acute defibrillation efficacy during ICD implants are in contrast to the recent trend in their internal medicine-trained counterparts. More studies are needed to determine if practice changes should be considered in the pediatric and adult congenital patient population.

Success rates in pediatric WPW ablation are improved with 3-dimensional mapping systems compared with fluoroscopy alone: a multicenter study.

INTRODUCTION: Three-dimensional mapping (3-D) systems are frequently used for ablation of supraventricular tachycardia. Prior studies have demonstrated radiation dosage reduction with 3-D, but there are no data on whether 3-D improves the efficacy of ablation of Wolff-Parkinson-White syndrome (WPW). We sought to determine if 3-D improves the success rate for ablation of WPW in children. METHODS: Multicenter retrospective study including patients ≤21 years of age with WPW undergoing ablation from 2008 to 2012. Success rates using the 2 techniques (3-D vs. fluoroscopy alone [FLUORO]) were compared. RESULTS: Six hundred and fifty-one cases were included (58% male, mean age 13 ± 4 years, 366 [56%] 3-D). Baseline characteristics including gender, weight, accessory pathway (AP) location, number of APs, and repeat ablation attempts were similar between the 2 groups (3-D and FLUORO) The 3-D group was slightly younger (12.7 ± 4.0 vs. 13.3 ± 4.0 years; P = 0.04) and less likely to undergo ablation utilizing cryoenergy (38 [10%] vs. 56 [20%]; P < 0.01). The 3-D group had a higher acute success rate of ablation (355 [97%] vs. 260 [91%]; P < 0.01). No differences were seen in recurrence (16 [5%] vs. 26 [9%]; P = 0.09) or complication rates (1 [0.3%] vs. 1 [0.4%]; P = 0.86) between the groups. On multivariable analysis, 3-D was shown to significantly improve success at ablation with an odds ratio of 3.1 (95% CI 1.44-6.72; P < 0.01). CONCLUSIONS: Use of 3-D significantly improved success rates for ablation of WPW in children. The increase in acute success associated with 3-D suggests it is an important adjunct for catheter ablation of WPW in children.

Creation of partial fascicular block: an approach to ablation of idiopathic left ventricular tachycardia in the pediatric population.

BACKGROUND: Catheter ablation of idiopathic left ventricular tachycardia in the pediatric population remains challenging. A recent multicenter study reported limited success with 14% not undergoing ablation due to inability to induce ventricular tachycardia (VT) or blood pressure instability during tachycardia. Creating complete or partial fascicular block with radiofrequency catheter ablation is a technique that may eliminate VT. This approach is performed during sinus rhythm, enabling atrioventricular conduction monitoring and maintaining stable hemodynamics. Importantly, induction of VT is not necessary for mapping or assessing efficacy of the procedure. METHODS: A retrospective review of pediatric patients (3-17 years) with recurrent, documented idiopathic left ventricular tachycardia by electrocardiogram who received catheter ablation by creating fascicular block as a therapeutic endpoint was performed. All had ablation at the site of an identified Purkinje potential. RESULTS: There were six patients with idiopathic left ventricular tachycardia, five originating from the posterior fascicle and one from the anterior fascicle. VT was not induced or spontaneous in four patients using programmed stimulation and isoproterenol infusion. All patients had a QRS axis shift following ablation, though none met criteria for fascicular block. At follow up (7-49 months, mean 27 months), all patients had persistence of this shift. There were no recurrences of VT and none of the patients were taking antiarrhythmic medication. CONCLUSION: The technique of creating partial fascicular block appears to be a safe and effective approach to ablation of idiopathic left ventricular tachycardia in children.

Lone atrial fibrillation in the young - perhaps not so "lone"?

OBJECTIVE: To determine if pediatric patients with a history of lone atrial fibrillation (AF) have other forms of supraventricular tachycardia (SVT) that may potentially trigger AF. STUDY DESIGN: A multicenter review of patients with lone AF who underwent electrophysiology (EP) study from 2006-2011 was performed. INCLUSION CRITERIA: age ≤21 years, normal ventricular function, structurally normal heart, history of AF, and EP study and/or ablation performed. EXCLUSION CRITERIA: congenital heart disease or cardiomyopathy. Patient demographics, findings at EP study and follow-up data were recorded. RESULTS: Eighteen patients met inclusion criteria. The mean age was 17.9 ± 2.2 years, weight was 82 ± 21 kg, body mass index was 27 ± 6, and 15 (83%) were males. Eleven (61%) were overweight or obese. Seven (39%) had inducible SVT during EP study: 5 atrioventricular nodal re-entry tachycardia (71%) and 2 concealed accessory pathways with inducible atrioventricular re-entry tachycardia (29%). All 7 patients with inducible SVT underwent radiofrequency ablation. There were no complications during EP study and/or ablation for all 18 patients. The mean follow-up was 1.7 ± 1.5 years and there were no recurrences in the 7 patients who underwent ablation. There were 2 recurrences of AF in patients with no other form of SVT during EP study. CONCLUSIONS: Inducible SVT was found in 39% of pediatric patients undergoing EP study for lone AF. EP study should be considered for pediatric patients presenting with lone AF.

Congenital long-QT syndrome in Addison's disease: a novel association.

This report describes a teenager found to have both Addision's disease and long-QT syndrome type 1. This association is unique, but congenital long-QT channelopathies have been associated with other endocrinopathies. It remains to be seen whether genetic investigation should be performed for all patients with long-QTc's and endocrinopathies.

Urgent permanent pacemaker implantation in critically ill preterm infants.

The management of complete heart block in premature low birth-weight infants, particularly those with hydrops fetalis, is challenging. We report emergent implantation of permanent epicardial pacemakers in the first 48 hours of life in two premature infants (one with hydrops fetalis) with birth weights of 1,400 grams and 1,000 grams.

Percutaneous right ventricular support during catheter ablation of intra-atrial reentrant tachycardia in an adult with a mustard baffle--a novel use of the Impella device.

Late sequelea following a Mustard operation for transposition of the great arteries (TGA) include atrial arrhythmias and dysfunction of the systemic right ventricle. Catheter mapping and ablation of atrial tachycardia in the setting of significant right ventricular dysfunction may result in hemodynamic compromise. We report the novel use of the Impella percutaneous microaxial flow pump to support cardiac output in an adult patient with a Mustard operation for TGA who experienced a cardiac arrest during a prior ablation attempt. The Impella device was placed via a retrograde approach across the aortic valve into the right ventricle providing hemodynamic stability for successful mapping and ablation of intra-atrial reentrant tachycardia.

Radiofrequency ablation of pediatric AV nodal reentrant tachycardia during the ice age: a single center experience in the cryoablation era.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Transatrial lead implantation using the 4-Fr lumenless pacing lead and delivery system in young adults with congenital heart disease.

We report the technique of transatrial delivery of the Medtronic 3830 SelectSecure lead (Medtronic Inc., Minneapolis, MN, USA) for right ventricular endocardial pacing in two young adults with congenital heart disease who had multiple pacing lead failures and superior vena cava occlusion. The deflectable catheter delivery system used to position the SelectSecure lead provided the opportunity to map the right ventricular endocardial surface and determine the best available pacing site. At midterm follow-up, both systems are functioning well.

Amiodarone for pediatric resuscitation: a word of caution.

Intravenous administration of amiodarone has recently been recommended for use during pediatric resuscitation of pediatric patients with ventricular fibrillation or pulseless ventricular tachycardia. We present two pediatric patients who received amiodarone for polymorphic ventricular tachycardia, although they were ultimately determined to have congenital long QT syndrome. Amiodarone is contraindicated in this setting and may have exacerbated the ventricular arrhythmia.

Electroanatomic mapping of the right coronary artery: a novel approach to ablation of right free-wall accessory pathways.

BACKGROUND: Catheter ablation of right free-wall (RFW) accessory pathways continues to be associated with lower success and higher recurrence rates compared with other pathway locations. Reliably identifying the precise location of RFW accessory pathways often contributes to the difficulty in ablating these pathways. Improved localization of RFW accessory pathways has been described utilizing multielectrode right coronary artery (RCA) catheterization. This approach has not been widely adopted, in part due to concerns of prolonged catheter placement within the RCA. We describe the technique of creating a 3-D electroanatomic map of the right atrioventricular groove, limiting the duration of a microcatheter within the RCA, to facilitate ablation of RFW accessory pathways. METHODS AND RESULTS: Following intracardiac identification of a RFW accessory pathway, an octapolar microcatheter was placed in the RCA. A 3-D electroanatomic map of the RCA was created during retrograde accessory pathway conduction using ventricular pacing. Immediately following creation of the map, the RCA catheter was removed. Endocardial mapping and ablation of the RFW accessory pathway was performed using the RCA electroanatomic map as a guide. This technique was used in four pediatric patients. The microcatheter was within the RCA for less than 1 min in all patients. Radiofrequency catheter ablation of the RFW accessory pathways were successfully performed with two lesions. There were no complications or recurrences at follow-up. CONCLUSIONS: The creation of a 3-D electroanantomic map of the RCA effectively localizes RFW accessory pathways and facilitates successful ablation. This technique minimizes the duration of RCA instrumentation.

Congenital cardiac surgery without routine placement of wires for temporary pacing.

OBJECTIVE: Temporary pacing wires have been associated with serious postoperative complications. Recommendations for their routine use after open heart surgery are decades old, and may not reflect current surgical techniques and outcomes. METHODS: The electronic web-enabled medical records of all patients undergoing congenital cardiac surgery from February, 2002, through December, 2005, were reviewed, excluding patients undergoing implantation of pacemakers as a primary procedure, or those undergoing ligation of a patent arterial duct. RESULTS: There were 1193 surgical procedures performed, 1041 with cardiopulmonary bypass. Median age of the patients was 5.8 months, with a range from 0 days to 54 years, weighing 6.2 kilograms, with a range from 1 to 114 kilograms. Mortality prior to discharge was 2.5%, and median postoperative stay was 6 days. No deaths were attributed to arrhythmias. Temporary pacing wires were placed 14 times (1.2%). Indications for placement included sinus nodal dysfunction in 8 patients, preoperative in 4 and intraoperative in 4, high degree atrioventricular block in 4 patients, and intraoperative atrial flutter in 2 patients. Of these patients, 4 (0.3%) eventually underwent permanent implantation of a pacemaker, 2 for persistent sinus nodal dysfunction, and 2 for persistent atrioventricular block. Postoperative junctional ectopic tachycardia requiring antiarrhythmic therapy occurred in 9 patients (0.8%). All recovered without incident, and none were treated with temporary pacing. CONCLUSIONS: The diminished risk of unexpected postoperative arrhythmias in the current era alleviates the necessity for routine placement of temporary pacing wires. Those institutions with experienced surgical and cardiac critical care teams may be able to predict the need for temporary pacing wires preoperatively or intraoperatively.

Radiofrequency ablation of probable atrioventricular nodal reentrant tachycardia in children with documented supraventricular tachycardia without inducible tachycardia.

The reproducible induction of supraventricular tachycardia (SVT) during electrophysiological study is critical for the diagnosis of atrioventricular nodal reentry tachycardia (AVNRT), and for determining a therapeutic endpoint for catheter ablation. In the sedated state, there are patients with reentry SVT due to AVNRT who are not inducible at electrophysiological study. This article reports on the empiric slow pathway modification for AVNRT in six pediatric patients (age 6-17, mean 13.3 years) with documented, recurrent, paroxysmal SVT in the setting of a structurally normal heart who were not inducible at electrophysiological study. Atrial and ventricular burst and extrastimulus pacing at multiple drive cycle lengths were performed in the baseline state, during an isuprel infusion, and during isuprel elimination. Single AV nodal (AVN) echo beats were present in all patients, while classic dual AVN physiology was present in three of six patients. Radiofrequency energy was administered in the right posteroseptal AV groove resulting in accelerated junctional rhythm in five of six patients. Postablation testing demonstrated the elimination of echo beats in four patients, while dual AVN physiology and echo beats persisted in two patients. At follow-up (22-49 months, mean 29.5 months), all patients are asymptomatic without recurrence of SVT and are not taking any antiarrhythmic medication. In selected patients, empiric slow pathway modification may be offered as a potential cure in children with recurrent paroxysmal SVT who are not inducible at electrophysiological study. Elimination of slow pathway conduction may serve as a surrogate endpoint, though is not necessary for long-term success.

The role of isoproterenol testing following radiofrequency catheter ablation of accessory pathways in children.

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.