Troponin elevation in the setting of exercise-induced rhabdomyolysis in an athletic teenager.

Troponin levels are often obtained when chest pain is evaluated in the paediatric emergency department. Elevations in troponin levels can be due to different causes, and it is important to fully understand all of these possible causes to help streamline further evaluation and therapy. We present the case of a teenager who had two episodes of troponin elevation in the setting of rhabdomyolysis.

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.

Transesophageal echocardiography of intracardiac thrombus in congenital heart disease and atrial flutter: the importance of thorough examination of the Fontan.

Transesophageal echocardiography (TEE) is used in atrial flutter or fibrillation (AFF) before electric cardioversion to detect intracardiac thrombi. Previous studies have described the use of TEE to diagnose intracardiac thrombi in the left atrium and left atrial appendage, which has an incidence of 8 % among patients without congenital heart disease (CHD). In their practice the authors have noted a significant incidence of intracardiac thrombi in other structures of patients with CHD and AFF. This study aimed to determine the incidence and location of intracardiac thrombi using TEE in patients with CHD requiring electric cardioversion of AFF and to compare the use of TEE and transthoracic echo (TTE) to detect intracardiac thrombus in this population. A retrospective chart review of TEE and TTE findings for all patients with CHD who had electric cardioversion of AFF at our institution from 2005 to 2013 was conducted. The diagnosis, presence, and location of intracardiac thrombus were determined. The TEE and TTE results were compared. The study identified 27 patients with CHD who met the study entry criteria at our institution between 2005 and 2013. Seven of these patients had a single ventricle with Fontan palliation. All the patients presented with AFF and had TEE before electric cardioversion. No patients were excluded from the study. The patients ranged in age from 2 to 72 years (median, 21 years) and weighed 17-100 kg (median, 65 kg). The duration of AFF before TEE and attempted cardioversion ranged from 1 day to 3 weeks (median, 3.5 days). Intracardiac thrombus was present in 18 % (5/27) of the patients and in 57 % (4/7) of the Fontan patients with AFF. No embolic events were reported acutely or during a 6-month follow-up period. Among patients with CHD who present with AFF, a particularly high incidence of intracardiac thrombi is present in the Fontan patients that may be difficult to detect by TTE. Thorough TEE examination of the Fontan and related structures is indicated before electric cardioversion of AFF. The incidence of intracardiac thrombus in CHD patients is more than double that reported in non-CHD patients.

Ablation of supraventricular tachycardia allows more liberal therapy in some children with attention-deficit-hyperactivity disorder.

BACKGROUND: First-line therapy for children with attention-deficit-hyperactivity disorder (ADHD) is stimulant medication, which may have potential cardiovascular side-effects. In patients with supraventricular tachycardia or Wolf-Parkinson-White syndrome (WPW), therapy for ADHD could become challenging. The purpose of the present study was to review the authors' experience of performing electrophysiologic study (EPS) with or without ablation to determine how it affected ADHD therapy. METHODS: Retrospective chart review of patients who underwent EPS between 2002 and 2009 was carried out. All patients under 21 years of age who had prior diagnosis of ADHD were included. RESULTS: Twenty patients met the inclusion criteria. The mean age was 12.1 ± 2.7 years (range: 5.6-16.8 years). The patients were diagnosed with ADHD on average 3.9 ± 2.7 years (range: 6 months-9 years) prior to the EPS. All patients had a structurally normal heart. Sixteen patients had cardiac symptoms. Seventeen patients underwent ablation of the arrhythmia substrate (16/17, 94% successful). Three patients with asymptomatic WPW were at low risk for life-threatening arrhythmias and did not have ablation. After the EPS, two patients had increased doses of their ADHD medications, and two patients whose health-care providers stopped the stimulant medication prior to EPS because of recurrent tachycardia were restarted on medications. All other patients on ADHD medications continued therapy. CONCLUSIONS: EPS for risk stratification and ablation of arrhythmia substrate is safe and effective, allowing more liberal therapy in patients with ADHD and supraventricular tachycardia or WPW.

Management and outcomes of atrial fibrillation in 241 healthy children and young adults: Revisiting "lone" atrial fibrillation-A multi-institutional PACES collaborative study.

BACKGROUND: Atrial fibrillation (AF) in healthy children and young adults is rare. Risk of recurrence and treatment efficacy are not well defined. OBJECTIVE: The purpose of this study was to assess recurrence patterns and treatment efficacy in AF. METHODS: A retrospective multicenter cohort study including 13 congenital heart centers was facilitated by the Pediatric & Congenital Electrophysiology Society (PACES). Patients ≤21 years of age with documented AF from January 2004 to December 2018 were included. Demographics, family and clinical history, medications, electrophysiological study parameters, and outcomes related to the treatment of AF were recorded and analyzed. Patients with contributory diseases were excluded. RESULTS: In 241 subjects (83% male; mean age at onset 16 years), AF recurred in 94 patients (39%) during 2.1 ± 2.6 years of follow-up. In multivariable analysis, predictors of AF recurrence were family history in a first-degree relative <50 years of age (odds ratio [OR] 1.9; P = .047) and longer PR interval in sinus rhythm (OR 1.1 per 10 ms; P = .037). AF recurrence was similar whether patients began no treatment (39/125 [31%]), began daily antiarrhythmic therapy (24/63 [38%]), or had an ablation at any time (14/53 [26%]; P = .39). Ablating non-AF substrate with supraventricular tachycardia improved freedom from AF recurrence (P = .013). CONCLUSION: Recurrence of AF in the pediatric population is common, and the incidence of recurrence was not impacted by "no treatment," "medication only," or "ablation" treatment strategy. Ablation of pathways and other reentrant targets was the only intervention that decreased AF recurrence in children and young adults.

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.

Ventricular pacing in single ventricles-A bad combination.

BACKGROUND: Chronic ventricular pacing (VP) is associated with systolic dysfunction in a subset of pediatric patients with heart block and structurally normal hearts. The effect of chronic VP in congenital heart disease is less well understood, specifically in the single-ventricle (SV) population. OBJECTIVE: To determine the longitudinal effect of VP in SV patients. METHODS: SV patients with heart block and dual-chamber pacemakers requiring >50% VP were compared with nonpaced (controls) SV patients matched for age, sex, and SV morphology. Patients were excluded if a prepacing echocardiogram was not available. Echocardiogram and clinical parameters were compared at baseline (prepacing) and at last follow-up in the paced group, and in controls when they were at ages similar to those of their paced-group matches. RESULTS: Twenty-two paced and 53 control patients from 2 institutions were followed for similar durations (6.6±5 years vs 7.6±7.6 years; P = .59). There was no difference between groups regarding baseline ventricular function or the presence of moderate-to-severe atrioventricular valvar regurgitation (AVVR). Paced patients were more likely to develop moderate-to-severe systolic dysfunction (68% vs 15%; P < .01) and AVVR (55% vs 8%; P < .001) and require heart failure medications (65% vs 21%; P < .001). Chronic VP was also associated with a higher risk of transplantation or death (odds ratio, 4.9; 95% confidence interval, 1.05-22.7; P = .04). CONCLUSIONS: SV patients requiring chronic VP are at higher risk of developing moderate-to-severe ventricular dysfunction and AVVR with an increased risk of death or transplantation compared with controls. New strategies to either limit VP or improve synchronization in this vulnerable population is imperative.

Use of dofetilide in adult patients with atrial arrhythmias and congenital heart disease: A PACES collaborative study.

BACKGROUND: Arrhythmia management has become the major treatment challenge in adult patients with congenital heart disease (ACHD). OBJECTIVE: We sought to investigate the utility and safety profile of dofetilide for atrial arrhythmias in ACHD. METHODS: A retrospective chart review was performed. We included patients (age ≥18 years) with congenital heart disease who had atrial fibrillation (AF) or intra-atrial reentrant tachycardia treated with dofetilide. RESULTS: We identified 64 patients with a mean age at initiation of 42 ± 14 years. ACHD type included single ventricle (n = 19, 30%), transposition of the great arteries (n = 14, 22%), atrial septal defect (n = 9, 14%), tetralogy of Fallot (n = 8, 12%), atrioventricular canal defect (n = 5, 8%), mitral/aortic stenosis (n = 7, 11%), and other (n = 2, 3%). Thirty-five (55%) had atrial fibrillation, and 29 (45%) had intra-atrial reentrant tachycardia. A total of 3 (4.7%) patients had major inpatient adverse events: torsades de pointes (n = 1, 1.5%), ventricular tachycardia (n = 1, 1.5%), and corrected QT prolongation requiring discontinuation (n = 1, 1.5%). Dofetilide was discontinued in 1 patient because of sinus node dysfunction, and another patient discontinued therapy before discharge because of persistent arrhythmia. Of the patients who were discharged on dofetilide (n = 59, 92%), 40 (68%) had adequate rhythm control and 19 (32%) had partial rhythm control. After a median follow-up of 3 years, 29 (49%) patients remained on dofetilide and 2 (3%) patients died. Reasons for discontinuation included waning effect (n = 16, 57%), side effects (n = 5, 18%), noncompliance (n = 2, 7%), successful ablation (n = 3, 11%), high cost (n = 1, 3.5%), and unknown (n = 1, 3.5%). CONCLUSION: Dofetilide remains a viable antiarrhythmic drug option in this challenging population. At 3 years, 49% remained on dofetilide. Close monitoring of renal function, concomitant medications, and corrected QT interval is required.

Experience with CartoSound for arrhythmia ablation in pediatric and congenital heart disease patients.

PURPOSE: Electro-anatomic mapping (EAM) has been used for more than a decade to assist in defining arrhythmia propagation for transcatheter ablation. Intra-cardiac echocardiography (ICE) has also gained acceptance as an adjunct to further define intracardiac anatomy. The integration of these two technologies (CartoSound, Biosense-Webster, Diamond Bar, CA, USA) is a recent development. In this report, we describe our early experience in the young, with and without congenital heart defects (CHD). METHODS: The clinical and electrophysiologic records of the first 17 patients to undergo procedures with the CartoSound (EAM-ICE) system were reviewed. In all 17, the 3-dimensional shape of the chamber(s) of interest was created using serial tracing of ICE images. The ICE catheter was placed in the esophagus in three and through the femoral vein in 14. Descriptive analysis was performed on demographic data as well as procedural characteristics including procedure time, fluoroscopy time, geometry acquisition time, EAM duration, ablation time, procedure success, and complications. RESULTS: Arrhythmias comprised intra-atrial re-entry tachycardia (13 patients, 76%), Wolff-Parkinson-White syndrome (1; 6%), ventricular ectopic tachycardia (2; 12%), and atrioventricular node re-entrant tachycardia (1; 6%). Thirteen had CHD, with a median two palliative operations; six had single-ventricle anatomy. Procedure duration was 266 ± 134 min (median ± SD), and fluoroscopy time was 29 ± 28.3 min. Geometry acquisition took 41 ± 35.4 min, or 16% of the total case duration. Ablation lesions were placed in 16 cases, (cooled tip in 12) of which 15 (94%) were successful. One patient experienced mild hypotension. ICE image quality in three patients with the probe placed in the esophagus was suboptimal. CONCLUSIONS: Advantages of CartoSound appear to be (1) anatomy modeling in the shape imposed by the arrhythmia, (2) more accurate geometry than EAM alone, and (3) demonstration of catheter position and lesions on echo during the study. Perceived disadvantages are (1) the large sheath required for ICE (11F), and (2) significant procedure time devoted to creation of anatomy. Optimal use may be to focus on key structures required for ablation, obtaining additional views as needed.