Epicardial Devices in Pediatrics and Congenital Heart Disease.

Epicardial cardiac implantable electronic device implant remains a common option in pediatric patients and certain patients with congenital heart disease due to patient size, complex anatomy, residual intracardiac shunts, and prior surgery precluding transvenous implant. Advantages include the lack of thromboembolic and vascular risks and ability to implant during concomitant surgery. Significant disadvantages include the occurrence of lead dysfunction that can result in bradycardia events in pacemaker patients, inappropriate shocks in implantable cardiac defibrillator patients, and overall a more invasive procedure.

"Acquired" Brugada syndrome in a cardiac allograft.

INTRODUCTION: Brugada syndrome is an inherited channelopathy characterized by arrhythmia and an increased risk of sudden cardiac death (SCD). Implantation of a defibrillator for primary or secondary prevention is the only effective strategy to decrease the risk of SCD in Brugada syndrome. We present a case in which a cardiac donor had a pathogenic variant for Brugada syndrome, discovered on genetic testing after transplantation. CASE REPORT: A young child with dilated cardiomyopathy underwent orthotopic heart transplantation from a donor with in-hospital cardiac arrest in the context of fever and a normal ECG. Approximately 1 month after transplant, the donor's post mortem genetic testing revealed a pathogenic loss-of-function SCN5A variant associated with Brugada syndrome, which was confirmed on genetic testing on a post-transplant endomyocardial biopsy from the recipient. The recipient's post-transplant electrocardiographic monitoring revealed persistent right bundle branch block and progressive, asymptomatic sinus node dysfunction. The recipient was managed with precautionary measures including aggressive fever management, avoidance of drugs that increase arrhythmia risk in Brugada syndrome, and increased frequency of arrhythmia surveillance. The recipient remains asymptomatic at over 3 years post-transplant with preserved graft function and no documented ventricular arrhythmias. CONCLUSION: We describe the clinical course of "acquired" Brugada syndrome in a cardiac allograft recipient, which has not been previously reported. The time-sensitive nature of donor organ selection, especially in critically ill recipients, combined with the growing use of molecular autopsies in patients with unexplained etiologies for death may increasingly result in important donor genetic information being made available after transplantation.

Ethical and Analytic Challenges With Genomic Sequencing of Relapsed Hematologic Malignancies Following Allogeneic Hematopoietic Stem-Cell Transplantation.

The implementation of precision medicine and next-generation sequencing technologies in the field of oncology is a novel approach being more widely studied and used in cases of high-risk primary and recurrent malignancies. Leukemias are the second most common cause of cancer-related mortality in children and the sixth most in adults. Relapsed leukemia represents a major component of the population that may benefit from genomic sequencing. However, ethical and analytic challenges arise when considering sequencing of biologic samples obtained from patients with relapsed leukemia following allogeneic hematopoietic stem-cell transplantation. Blood from the recipient after transplantation would include donor-derived cells and thus, genomic sequencing of recipient blood will interrogate the donor germline in addition to the somatic genetic profile of the leukemia cells and the recipient germline. This is a situation for which the donor will not have typically provided consent and may be particularly problematic if actionable secondary or incidental findings related to the donor are uncovered. We present the challenges raised in this scenario and provide strategies to mitigate this risk.

ACC/AHA/ASE/HRS/ISACHD/SCAI/SCCT/SCMR/SOPE 2020 Appropriate Use Criteria for Multimodality Imaging During the Follow-Up Care of Patients With Congenital Heart Disease: A Report of the American College of Cardiology Solution Set Oversight Committee and Appropriate Use Criteria Task Force, American Heart Association, American Society of Echocardiography, Heart Rhythm Society, International Society for Adult Congenital Heart Disease, Society for Cardiovascular Angiography and Interventions, Society of Cardiovascular Computed Tomography, Society for Cardiovascular Magnetic Resonance, and Society of Pediatric Echocardiography.

The American College of Cardiology (ACC) collaborated with the American Heart Association, American Society of Echocardiography, Heart Rhythm Society, International Society for Adult Congenital Heart Disease, Society for Cardiovascular Angiography and Interventions, Society of Cardiovascular Computed Tomography, Society for Cardiovascular Magnetic Resonance, and the Society of Pediatric Echocardiography to develop Appropriate Use Criteria (AUC) for multimodality imaging during the follow-up care of patients with congenital heart disease (CHD). This is the first AUC to address cardiac imaging in adult and pediatric patients with established CHD. A number of common patient scenarios (also termed "indications") and associated assumptions and definitions were developed using guidelines, clinical trial data, and expert opinion in the field of CHD.1 The indications relate primarily to evaluation before and after cardiac surgery or catheter-based intervention, and they address routine surveillance as well as evaluation of new-onset signs or symptoms. The writing group developed 324 clinical indications, which they separated into 19 tables according to the type of cardiac lesion. Noninvasive cardiac imaging modalities that could potentially be used for these indications were incorporated into the tables, resulting in a total of 1,035 unique scenarios. These scenarios were presented to a separate, independent panel for rating, with each being scored on a scale of 1 to 9, with 1 to 3 categorized as "Rarely Appropriate," 4 to 6 as "May Be Appropriate," and 7 to 9 as "Appropriate." Forty-four percent of the scenarios were rated as Appropriate, 39% as May Be Appropriate, and 17% as Rarely Appropriate. This AUC document will provide guidance to clinicians in the care of patients with established CHD by identifying the reasonable imaging modality options available for evaluation and surveillance of such patients. It will also serve as an educational and quality improvement tool to identify patterns of care and reduce the number of Rarely Appropriate tests in clinical practice.

Catheter ablation of supraventricular tachycardia after tricuspid valve surgery in patients with congenital heart disease: A multicenter comparative study.

BACKGROUND: Tricuspid valve (TV) surgery is often required for adult congenital heart disease (ACHD), but may hinder catheter ablation when an artificial material or imbricated tissue covers the tricuspid annulus. OBJECTIVE: The purpose of this study was to determine the outcomes of catheter ablation after TV surgery in a large ACHD cohort. METHODS: An international retrospective study involving 7 centers was conducted. Patients who did and did not undergo TV surgery were matched for age, lesion classification, and postsurgical duration. TV operations were classified as valve ring/replacement vs repair. RESULTS: One hundred thirty-six patients (42 ring/replacement, 39 repair, and 55 no TV surgery; median 32 years [IQR 20 - 46]) underwent 180 procedures targeting 239 tachycardias (cavotricuspid-isthmus dependent intraatrial reentrant tachycardia 36%, other intraatrial reentrant tachycardia 29%, focal atrial tachycardia 18%, and other supraventricular tachyarrhythmia 17%). Post-TV surgery, procedures were longer (4.3 hours vs 3.3 hours; P = .003) and required longer fluoroscopy time (31 minutes vs 18 minutes; P = .001). At least partial acute success was achieved in 81% of procedures in the TV ring/replacement group vs 94% in both TV repair and no TV surgery groups (P = .03). The difference was driven mainly by ablation of annular substrates, with acute success in 73% of TV ring/replacement, 92% of TV repair, and 94% of no TV surgery groups (P = .01). Over a median of 3.0 years, tachycardia recurred after 26% of procedures. TV ring/replacement predicted recurrence in the multivariable analysis (hazard ratio 2.4; 95% confidence interval 1.2-5.2; P = .009). CONCLUSION: After surgery for ACHD, catheter ablation success was lower and tachycardia recurrence was higher after TV valve ring/replacement surgery. The findings of this retrospective report support future larger multicenter series and prospective evaluation to determine the role of empirical annular substrate ablation.

Hemodynamic effects of sustained postoperative cardiac resynchronization therapy in infants after repair of congenital heart disease: Results of a randomized clinical trial.

BACKGROUND: It is unknown whether continuous cardiac resynchronization therapy (CRT) can lead to sustained improvement in hemodynamics after surgery for congenital heart disease (CHD). OBJECTIVE: We investigated whether CRT improves cardiac index (CI) and blood pressure in infants after biventricular repair of CHD. METHODS: We randomized infants younger than 4 months after biventricular CHD surgery to standard care or standard care plus CRT for 48 hours or until extubation if sooner. Change in the primary outcome of CI and blood pressure over time was compared between groups. For subgroup analysis, QRS duration was considered prolonged if greater than the 98th percentile. RESULTS: Forty-two patients were randomized: 21 controls and 21 patients receiving CRT (median weight 4 kg). There were no identified adverse events from pacing. The change in CI over time was not different between patients receiving CRT and controls, but trended toward improvement in patients with wide QRS who received CRT (n = 9) vs controls with wide QRS (n = 8) (+1.65 (0.86) L/(min·m2); P = .06). Controls with wide QRS experienced the smallest increase in CI (0.33 L/(min·m2)). Blood pressure was significantly higher in infants with wide QRS who received CRT than in controls (+7.14 (3.08) mm Hg; P = .02). Serum lactate level, catecholamine use, ventilation time, and length of intensive care unit stay were similar between the 2 groups. CONCLUSION: CRT improved blood pressure and a trend toward higher CI in infants after repair of biventricular CHD with prolonged QRS duration. These findings warrant further study of CRT to improve postoperative recovery in infants with electrical dyssynchrony.

The effect of NavX on fluoroscopy times in pediatric catheter ablation.

PURPOSE: Catheter ablation is the established curative therapy for pediatric tachyarrhythmias. However, exposure to ionizing radiation from fluoroscopy during the procedure is of concern to both patients and caregivers. We sought to assess the impact of an impedance-based three-dimensional navigation system (NavX(TM), Endocardial Solutions, Inc., St. Paul, MN) on pediatric catheter ablation procedures. METHODS: We retrospectively analyzed procedural data during a 7-year period (2002-2008), which spanned the transition between standard fluoroscopic mapping and adoption of NavX(TM) mapping for catheter ablation of atrioventricular nodal reentrant tachycardia (AVNRT) and right/left-sided accessory pathways (RAP/LAP). Comparisons of total procedure time, total fluoroscopy time, and ablation fluoroscopy time (from insertion of ablation catheter until completion of procedure) between NavX(TM) and conventional mapping were made. RESULTS: Three hundred eighty-eight patients (aged 1-18 years, M/F 236:183) underwent ablation of AVNRT (n = 101), LAP (n = 130), or RAP (n = 157) using either conventional (n = 70) or NavX(TM) (n = 318) mapping. Overall success rates were similar between the two mapping approaches (95.7% for conventional versus 95.9% for NavX(TM)). NavX(TM) mapping significantly reduced ablation fluoroscopy time (15.9 ± 14.3 versus 11.0 ± 8.9 min for NavX(TM), p < 0.01) with a trend towards a decrease in total fluoroscopy time (26.4 ± 15.6 versus 23.8 ± 11.1 min for NavX(TM), p = 0.095). Total procedure time was not significantly different between the two methods (210.1 ± 66 versus 222.8 ± 61 min for NavX(TM), p = 0.13). When analyzed by arrhythmia substrate, there were significant reductions in ablation fluoroscopy time for both LAP and RAP. CONCLUSIONS: NavX(TM) mapping reduced ablation fluoroscopy times for accessory pathways during pediatric catheter ablation.

Functional status, heart rate, and rhythm abnormalities in 521 Fontan patients 6 to 18 years of age.

OBJECTIVES: Our objective was to determine the relationship between functional outcome and abnormalities of heart rate and rhythm after the Fontan operation. METHODS: The National Heart, Lung, and Blood Institute Pediatric Heart Network conducted a cross-sectional analysis of patients who had undergone a Fontan procedure at the 7 network centers. Analysis was based on 521 patients with an electrocardiogram (n = 509) and/or bicycle exercise test (n = 404). The Child Health Questionnaire parent report and the oxygen consumption at the anaerobic threshold were used as markers of functional outcome. RESULTS: Various Fontan procedures had been performed: intracardiac lateral tunnel (59%), atriopulmonary connection (14%), extracardiac later tunnel (13%), and extracardiac conduit (11%). Prior volume unloading surgery was performed in 389 patients: bidirectional Glenn (70%) and hemi-Fontan (26%). A history of atrial tachycardia was noted in 9.6% of patients and 13.1% of patients had a pacemaker. Lower resting heart rate and higher peak heart rate were each weakly associated with better functional status, as defined by higher anaerobic threshold (R = -0.18, P = .004, and R = 0.16, P = .007, respectively) and higher Child Health scores for physical functioning (R = -0.18, P < .001, and R = 0.17, P = .002, respectively). Higher anaerobic threshold was also independently associated with younger age and an abnormal P-axis. Resting bradycardia was not associated with anaerobic threshold or Child Health scores. CONCLUSIONS: In pediatric patients (6-18 years) after the Fontan procedure, a lower resting heart rate and a higher peak heart rate are each independently associated with better physical function as measured by anaerobic threshold and Child Health scores. However, these correlations are weak, suggesting that other, nonrhythm and nonrate, factors may have a greater impact on the functional outcome of pediatric patients after the Fontan operation.

A multicenter experience with novel implantable cardioverter defibrillator configurations in the pediatric and congenital heart disease population.

INTRODUCTION: In pediatric and congenital heart disease patients, transvenous ICD implantation may be limited secondary to patient size, venous, or cardiac anatomy. Epicardial patches require a thoracotomy, and may lead to a restrictive pericardial process. Because of these issues, we have explored novel ICD configurations. METHODS: Retrospective review at 10 centers implanting ICDs without a transvenous shocking coil or epicardial patches. RESULTS: Twenty-two patients underwent implant at a mean age of 8.9 years (range: 0.3-43.5), with a mean weight of 25.5 kg (range: 5.2-70). Diagnoses included complex CHD, intracardiac tumors, cardiomyopathy, idiopathic VT, LV noncompaction, and long QT syndrome. Three configurations were used: subcutaneous array, a transvenous design ICD lead placed on the epicardium, or a transvenous design ICD lead placed subcutaneously. Difficulties were found at implant in 8 patients: 4 had difficulty inducing VT/VF, and 4 had high DFTs. Over a mean follow-up of 2.2 years (range: 0.2-10.5), 7 patients had appropriate shocks. Inappropriate shocks occurred in 4 patients. System revisions were required in 7 patients: 2 generator changes (in 1 patient), 3 pace-sense lead replacement, 1 additional subcutaneous coil placement due to increased DFT, 1 upgrade to a transvenous system, and 1 revision to epicardial patch system. CONCLUSIONS: ICD implantation can be performed without epicardial patches or transvenous high-energy leads in this population, using individualized techniques. This will allow ICD use in patients who have intracardiac shunting or are deemed too small for transvenous ICD leads. The long-term outcome and possible complications are as yet unknown in this population, and they should be monitored closely with follow-up DFTs.

Implantable cardioverter defibrillator lead complications and laser extraction in children and young adults with congenital heart disease: implications for implantation and management.

INTRODUCTION: Implantable cardioverter defibrillators (ICDs) are being implanted for primary and secondary prevention of sudden death in children and young adults with congenital heart disease. Over time, ICD leads adhere to venous endothelium and endocardium. Lead removal, when necessary, often requires disruption of this fibrous tissue. METHODS AND RESULTS: We retrospectively reviewed and analyzed our experience with ICD lead extraction in children and young adults with congenital heart disease. From April 1999 through January 2002, 14 patients underwent 15 lead extraction procedures to remove 21 leads (17 ICD leads and 4 pacing or sensing leads). Seven patients had surgically corrected structural heart disease (5 transposition of the great arteries with atrial switch repair and 2 corrected tetralogy of Fallot). Mean patient age at extraction was 17.9 +/- 5.7 years (range 9-32), and mean duration of lead implantation was 42.0 +/- 18.9 months (range 15-75). Fourteen of 15 procedures were performed for lead fracture or failure. A laser sheath was used for 20 of 21 lead extractions. Twenty of 21 leads (95%) were completely extracted. There were three instances of blood loss requiring transfusion. There were no major complications or deaths. CONCLUSION: Young congenital heart disease patients with an ICD are at risk for growth-related lead distortion. The use of a laser sheath is safe and effective for ICD lead extraction in congenital heart disease patients, despite coil adherence and altered anatomy. It may be advisable to avoid dual-coil leads in patients with the potential for future growth.

Circadian and seasonal variation of malignant arrhythmias in a pediatric and congenital heart disease population.

INTRODUCTION: Recent studies in adult populations have revealed seasonal variation in the frequency of acute cardiovascular events, including life-threatening arrhythmias, demonstrating increased events during winter and early spring. Trends in the time of day that arrhythmias occur also were noted. We sought to establish whether pediatric and young adult congenital heart disease implantable cardioverter defibrillator (ICD) recipients have circadian or seasonal variability in shock frequency, similar to adult populations. METHODS AND RESULTS: Data from ICD patients at six pediatric centers in North America were analyzed to assess the timing of life-threatening arrhythmias. The populations consisted of children and adults with congenital heart disease and ICDs placed for malignant arrhythmias. Data were considered in 46 patients who received appropriate therapy (total 139 episodes) for ventricular tachycardia or ventricular fibrillation. Multiple variables were analyzed, including time of day, day of week, and month of year. In contrast to previously studied adult patients, fewer events occurred in the early morning (7.5%), with the most therapies occurring between 6 P.M. and midnight (35%). An increased frequency of therapies was observed in the fall and winter (September-January), representing 60% of all appropriate shocks. Unlike adult populations, Mondays did not have an increased frequency of malignant arrhythmias. CONCLUSION: Pediatric and adult congenital heart disease populations have moderate seasonal and 24-hour variation in ICD event rate, with some distinctly different peaks than those seen in typical adult ICD populations. These findings suggest circadian variation in arrhythmia vulnerability that may differ from conventional occupational, physical, or emotional stressors. (J Cardiovasc Electrophysiol, Vol. 13, pp.