Efficacy and safety of early postoperative ablation in patients with congenital heart disease.

BACKGROUND: Postoperative arrhythmias are most often transient and medically treated, but some patients may require electrophysiology study (EPS) and ablation. OBJECTIVE: The purpose of this study was to describe the efficacy and safety of early postoperative ablation. METHODS: This study presents a retrospective series of patients who underwent EPS within 12 months of surgery for congenital heart disease between 2000 and 2021. The procedural outcome included complete or partial success, failure or empirical ablation, and complications. The long-term outcome included arrhythmia recurrence and burden according to a 12-point clinical arrhythmia severity score (documented arrhythmia, arrhythmia severity, cardioversion, and antiarrhythmic medication). RESULTS: Among 28,902 surgeries during the study period, 24 patients (0.1%) underwent EPS within 3 months of surgery and 26 (0.1%) 3-12 months after surgery. Most patients had great (n = 27 [50%]) or moderate (n = 21 [42%]) congenital heart disease complexity. Mechanisms of arrhythmias included intra-atrial reentrant tachycardia (n = 23 [46%]), ectopic atrial tachycardia (n = 13 [26%]), accessory pathway (n = 6 [12%]), atrioventricular nodal reentrant tachycardia (n = 7 [14%]), twin atrioventricular node (n = 1 [2%]), atrial fibrillation (n = 1 [2%]), junctional ectopic tachycardia (n = 1 [2%]), and ventricular tachycardia (n = 2 [4%]). The procedure was acutely successful in 41 patients (82%), empirical in 5 (10%), and unsuccessful in 4 (8%). Complications occurred in 4 patients (major in 1, moderate in 1, and minor in 2). The recurrence of arrhythmia was documented in 27 patients (54%), although the burden of arrhythmia was significantly reduced. CONCLUSION: A minority of patients require early postoperative EPS and ablation. For those, the procedure can be performed with reasonable acute success and manageable morbidity even in critically ill patients with complex surgical anatomy.

Electrocardiogram-Based Deep Learning to Predict Mortality in Repaired Tetralogy of Fallot.

BACKGROUND: Artificial intelligence-enhanced electrocardiogram (AI-ECG) analysis shows promise to predict mortality in adults with acquired cardiovascular diseases. However, its application to the growing repaired tetralogy of Fallot (rTOF) population remains unexplored. OBJECTIVES: This study aimed to develop and externally validate an AI-ECG model to predict 5-year mortality in rTOF. METHODS: A convolutional neural network was trained on electrocardiograms (ECGs) obtained at Boston Children's Hospital and tested on Boston (internal testing) and Toronto (external validation) INDICATOR (International Multicenter TOF Registry) cohorts to predict 5-year mortality. Model performance was evaluated on single ECGs per patient using area under the receiver operating (AUROC) and precision recall (AUPRC) curves. RESULTS: The internal testing and external validation cohorts comprised of 1,054 patients (13,077 ECGs at median age 17.8 [Q1-Q3: 7.9-30.5] years; 54% male; 6.1% mortality) and 335 patients (5,014 ECGs at median age 38.3 [Q1-Q3: 29.1-48.7] years; 57% male; 8.4% mortality), respectively. Model performance was similar during internal testing (AUROC 0.83, AUPRC 0.18) and external validation (AUROC 0.81, AUPRC 0.21). AI-ECG performed similarly to the biventricular global function index (an imaging biomarker) and outperformed QRS duration. AI-ECG 5-year mortality prediction, but not QRS duration, was a significant independent predictor when added into a Cox regression model with biventricular global function index to predict shorter time-to-death on internal and external cohorts. Saliency mapping identified QRS fragmentation, wide and low amplitude QRS complexes, and flattened T waves as high-risk features. CONCLUSIONS: This externally validated AI-ECG model may complement imaging biomarkers to improve risk stratification in patients with rTOF.

Deep Learning-Based Electrocardiogram Analysis Predicts Biventricular Dysfunction and Dilation in Congenital Heart Disease.

BACKGROUND: Artificial intelligence-enhanced electrocardiogram (AI-ECG) analysis shows promise to detect biventricular pathophysiology. However, AI-ECG analysis remains underexplored in congenital heart disease (CHD). OBJECTIVES: The purpose of this study was to develop and externally validate an AI-ECG model to predict cardiovascular magnetic resonance (CMR)-defined biventricular dysfunction/dilation in patients with CHD. METHODS: We trained (80%) and tested (20%) a convolutional neural network on paired ECG-CMRs (≤30 days apart) from patients with and without CHD to detect left ventricular (LV) dysfunction (ejection fraction ≤40%), RV dysfunction (ejection fraction ≤35%), and LV and RV dilation (end-diastolic volume z-score ≥4). Performance was assessed during internal testing and external validation on an outside health care system using area under receiver-operating curve (AUROC) and area under precision recall curve. RESULTS: The internal and external cohorts comprised 8,584 ECG-CMR pairs (n = 4,941; median CMR age 20.7 years) and 909 ECG-CMR pairs (n = 746; median CMR age 25.4 years), respectively. Model performance was similar for internal testing (AUROC: LV dysfunction 0.87; LV dilation 0.86; RV dysfunction 0.88; RV dilation 0.81) and external validation (AUROC: LV dysfunction 0.89; LV dilation 0.83; RV dysfunction 0.82; RV dilation 0.80). Model performance was lowest in functionally single ventricle patients. Tetralogy of Fallot patients predicted to be at high risk of ventricular dysfunction had lower survival (P < 0.001). Model explainability via saliency mapping revealed that lateral precordial leads influence all outcome predictions, with high-risk features including QRS widening and T-wave inversions for RV dysfunction/dilation. CONCLUSIONS: AI-ECG shows promise to predict biventricular dysfunction/dilation, which may help inform CMR timing in CHD.

Pediatric Electrocardiogram-Based Deep Learning to Predict Secundum Atrial Septal Defects.

Secundum atrial septal defect (ASD2) detection is often delayed, with the potential for late diagnosis complications. Recent work demonstrated artificial intelligence-enhanced ECG analysis shows promise to detect ASD2 in adults. However, its application to pediatric populations remains underexplored. In this study, we trained a convolutional neural network (AI-pECG) on paired ECG-echocardiograms (≤ 2 days apart) to detect ASD2 from patients ≤ 18 years old without major congenital heart disease. Model performance was evaluated on the first ECG-echocardiogram pair per patient for Boston Children's Hospital internal testing and emergency department cohorts using area under the receiver operating (AUROC) and precision-recall (AUPRC) curves. The training cohort comprised of 92,377 ECG-echocardiogram pairs (46,261 patients; median age 8.2 years) with an ASD2 prevalence of 6.7%. Test groups included internal testing (12,631 patients; median age 7.4 years; 6.9% prevalence) and emergency department (2,830 patients; median age 7.5 years; 4.9% prevalence) cohorts. Model performance was higher in the internal test (AUROC 0.84, AUPRC 0.46) cohort than the emergency department cohort (AUROC 0.80, AUPRC 0.30). In both cohorts, AI-pECG outperformed ECG findings of incomplete right bundle branch block. Model explainability analyses suggest high-risk limb lead features include greater amplitude P waves (suggestive of right atrial enlargement) and V1 RSR' (suggestive of RBBB). Our findings demonstrate the promise of AI-pECG to inexpensively screen and/or detect ASD2 in pediatric patients. Future multicenter validation and prospective trials to inform clinical decision making are warranted.

Comparative utility of omnipolar and bipolar electroanatomic mapping methods to detect and localize dual nodal substrate in patients with atrioventricular nodal reentrant tachycardia.

BACKGROUND: Catheter-based slow pathway modification (SPM) for atrioventricular nodal reentrant tachycardia (AVNRT) is traditionally performed at empiric sites using anatomical landmarks and test ablation feedback within the triangle of Koch (TK). While studies have described more tailored techniques such as bipolar low voltage bridge (LVB) and wavefront collision identification, few have systematically compared the diagnostic yields of each and none have investigated whether omnipolar mapping technology provides incremental benefit. The objective of this study was to compare the utility of omnipolar and bipolar-derived qualitative and quantitative measurements in identifying and localizing dual AVN substrate in patients with versus without AVNRT. METHODS: A retrospective case-control study of consecutive patients with paroxysmal supraventricular tachycardia undergoing electrophysiology study with both omnipolar and bipolar mapping from 2022-2023. RESULTS: Thirteen AVNRT cases (median age 16.1 years, 512 TK points) were compared to nine non-AVNRT controls (median age 15.7 years, 332 TK points). Among qualitative variables, an omnipolar activation vector pivot, defined as a ≥45 degree change in activation direction within the TK, had the highest positive (81%) and negative predictive values (100%) for identifying AVNRT cases and had a median distance of 1 mm from SPM sites. Among quantitative variables, the optimal discriminatory performance for successful SPM sites was observed using bipolar voltage restricted to a peak frequency >340 Hz (c statistic 0.75). CONCLUSIONS: Omnipolar vector pivot analysis represents an automated, annotation-independent qualitative technique that is sensitive and specific for AVNRT substrate and co-localizes with successful SPM sites. Bipolar voltage quantitatively describes SP anisotropy better than omnipolar voltage, and the addition of peak frequency signal analysis further optimizes the selection of SPM sites.

Limited Relationship Between Echocardiographic Measures and Electrocardiographic Markers of Left Ventricular Size in Healthy Children.

Pediatric ECG standards have been defined without echocardiographic confirmation of normal anatomy. The Pediatric Heart Network Normal Echocardiogram Z-score Project provides a racially diverse group of healthy children with normal echocardiograms. We hypothesized that ECG and echocardiographic measures of left ventricular (LV) dimensions are sufficiently correlated in healthy children to imply a clinically meaningful relationship. This was a secondary analysis of a previously described cohort including 2170 digital ECGs. The relationship between 6 ECG measures associated with LV size were analyzed with LV Mass (LVMass-z) and left ventricular end-diastolic volume (LVEDV-z) along with 11 additional parameters. Pearson or Spearman correlations were calculated for the 78 ECG-echocardiographic pairs with regression analyses assessing the variance in ECG measures explained by variation in LV dimensions and demographic variables. ECG/echocardiographic measurement correlations were significant and concordant in 41/78 (53%), though many were significant and discordant (13/78). Of the 6 ECG parameters, 5 correlated in the clinically predicted direction for LV Mass-z and LVEDV-z. Even when statistically significant, correlations were weak (0.05-0.24). R2 was higher for demographic variables than for echocardiographic measures or body surface area in all pairs, but remained weak (R2 ≤ 0.17). In a large cohort of healthy children, there was a positive association between echocardiographic measures of LV size and ECG measures of LVH. These correlations were weak and dependent on factors other than echocardiographic or patient derived variables. Thus, our data support deemphasizing the use of solitary, traditional measurement-based ECG markers traditionally thought to be characteristic of LVH as standalone indications for further cardiac evaluation of LVH in children and adolescents.

Pediatric ECG-Based Deep Learning to Predict Left Ventricular Dysfunction and Remodeling.

BACKGROUND: Artificial intelligence-enhanced ECG analysis shows promise to detect ventricular dysfunction and remodeling in adult populations. However, its application to pediatric populations remains underexplored. METHODS: A convolutional neural network was trained on paired ECG-echocardiograms (≤2 days apart) from patients ≤18 years of age without major congenital heart disease to detect human expert-classified greater than mild left ventricular (LV) dysfunction, hypertrophy, and dilation (individually and as a composite outcome). Model performance was evaluated on single ECG-echocardiogram pairs per patient at Boston Children's Hospital and externally at Mount Sinai Hospital using area under the receiver operating characteristic curve (AUROC) and area under the precision-recall curve (AUPRC). RESULTS: The training cohort comprised 92 377 ECG-echocardiogram pairs (46 261 patients; median age, 8.2 years). Test groups included internal testing (12 631 patients; median age, 8.8 years; 4.6% composite outcomes), emergency department (2830 patients; median age, 7.7 years; 10.0% composite outcomes), and external validation (5088 patients; median age, 4.3 years; 6.1% composite outcomes) cohorts. Model performance was similar on internal test and emergency department cohorts, with model predictions of LV hypertrophy outperforming the pediatric cardiologist expert benchmark. Adding age and sex to the model added no benefit to model performance. When using quantitative outcome cutoffs, model performance was similar between internal testing (composite outcome: AUROC, 0.88, AUPRC, 0.43; LV dysfunction: AUROC, 0.92, AUPRC, 0.23; LV hypertrophy: AUROC, 0.88, AUPRC, 0.28; LV dilation: AUROC, 0.91, AUPRC, 0.47) and external validation (composite outcome: AUROC, 0.86, AUPRC, 0.39; LV dysfunction: AUROC, 0.94, AUPRC, 0.32; LV hypertrophy: AUROC, 0.84, AUPRC, 0.25; LV dilation: AUROC, 0.87, AUPRC, 0.33), with composite outcome negative predictive values of 99.0% and 99.2%, respectively. Saliency mapping highlighted ECG components that influenced model predictions (precordial QRS complexes for all outcomes; T waves for LV dysfunction). High-risk ECG features include lateral T-wave inversion (LV dysfunction), deep S waves in V1 and V2 and tall R waves in V6 (LV hypertrophy), and tall R waves in V4 through V6 (LV dilation). CONCLUSIONS: This externally validated algorithm shows promise to inexpensively screen for LV dysfunction and remodeling in children, which may facilitate improved access to care by democratizing the expertise of pediatric cardiologists.

Medical cardioversion of atrial fibrillation and flutter with class IC antiarrhythmic drugs in young patients with and without congenital heart disease.

INTRODUCTION: The use of flecainide and propafenone for medical cardioversion of atrial fibrillation (AF) and atrial flutter/intra-atrial reentrant tachycardia (IART) is well-described in adults without congenital heart disease (CHD). Data are sparse regarding their use for the same purpose in adults with CHD and in adolescent patients with anatomically normal hearts and we sought to describe the use of class IC drugs in this population and identify factors associated with decreased likelihood of success. METHODS: Single center retrospective cohort study of patients who received oral flecainide or propafenone for medical cardioversion of AF or IART from 2000 to 2022. The unit of analysis was each episode of AF/IART. We performed a time-to-sinus rhythm analysis using a Cox proportional hazards model clustering on the patient to identify factors associated with increased likelihood of success. RESULTS: We identified 45 episodes involving 41 patients. As only episodes of AF were successfully cardioverted with medical therapy, episodes of IART were excluded from our analyses. Use of flecainide was the only factor associated with increased likelihood of success. There was a statistically insignificant trend toward decreased likelihood of success in patients with CHD. CONCLUSIONS: Flecainide was more effective than propafenone. We did not detect a difference in rate of conversion to sinus rhythm between patients with and without CHD and were likely underpowered to do so, however, there was a trend toward decreased likelihood of success in patients with CHD. That said, medical therapy was effective in >50% of patients with CHD with AF.

Ventricular Arrhythmias in Adults With Congenital Heart Disease, Part I: JACC State-of-the-Art Review.

Patients with congenital heart disease associated with a higher risk for ventricular arrhythmias (VA) and sudden cardiac death (SCD) can be divided conceptually into those with discrete mechanisms for reentrant monomorphic ventricular tachycardia (VT) (Group A) and those with more diffuse substrates (Group B). Part I of this review addresses Group A lesions, which predominantly consist of tetralogy of Fallot and related variants. Well-defined anatomic isthmuses for reentrant monomorphic VT are interposed between surgical scars and the pulmonary or tricuspid annulus. The most commonly implicated critical isthmus for VT is the conal septum that divides subpulmonary from subaortic outlets. Programmed ventricular stimulation can be helpful in risk stratification. Although catheter ablation is not generally considered an alternative to the implantable cardioverter-defibrillator (ICD) for prevention of SCD, emerging data suggest that there is a subset of carefully selected patients who may not require ICDs after successful monomorphic VT ablation.

Ventricular Arrhythmias in Adults With Congenital Heart Disease, Part II: JACC State-of-the-Art Review.

There are marked variations in the incidence of sudden cardiac death (SCD) and in the substrates for ventricular arrhythmias (VAs) across the gamut of congenital heart defects. In this 2-part review, patients with higher-risk forms of congenital heart disease (CHD) were conceptually categorized into those with discrete anatomic isthmuses for macro-reentrant ventricular tachycardia (VT) (Group A) and those with more diffuse or less well-defined substrates (Group B) that include patchy or extensive myocardial fibrosis. The latter category encompasses CHD lesions such as Ebstein anomaly, transposition of the great arteries with a systemic right ventricle (RV), and congenital aortic stenosis. For Group B patients, polymorphic VT and ventricular fibrillation account for a higher proportion of VA. The prognostic value of programmed ventricular stimulation is less well established, and catheter ablation plays a less prominent role. As cardiomyopathies evolve over time, pathophysiological mechanisms for VA among Groups A and B become increasingly blurred.

Insight into the Role of the Child Opportunity Index on Surgical Outcomes in Congenital Heart Disease.

OBJECTIVE: To use neighborhood-level Child Opportunity Index (COI) measures to investigate disparities in congenital heart surgery postoperative outcomes and identify potential targets for intervention. STUDY DESIGN: In this single-institution retrospective cohort study, children <18 years old who underwent cardiac surgery between 2010 and 2020 were included. Patient-level demographics and neighborhood-level COI were used as predictor variables. COI-a composite US census tract-based score measuring educational, health/environmental, and social/economic opportunities-was dichotomized as lower (<40th percentile) vs higher (≥40th percentile). Cumulative incidence of hospital discharge was compared between groups using death as a competing risk, adjusting for clinical characteristics associated with outcomes. Secondary outcomes included hospital readmission and death within 30 days. RESULTS: Among 6247 patients (55% male) with a median age of 0.8 years (IQR, 0.2-4.3), 26% had lower COI. Lower COI was associated with longer hospital lengths of stay (adjusted HR, 1.2; 95% CI, 1.1-1.2; P < .001) and an increased risk of death (adjusted OR, 2.0; 95% CI. 1.4-2.8; P < .001), but not hospital readmission (P = .6). At the neighborhood level, lacking health insurance coverage, food/housing insecurity, lower parental literacy and college attainment, and lower socioeconomic status were associated with longer hospital length of stay and increased risk of death. At the patient-level, public insurance (adjusted OR, 1.4; 95% CI, 1.0-2.0; P = .03) and caretaker Spanish language (adjusted OR 2.4; 95% CI, 1.2-4.3; P < .01) were associated with an increased risk of death. CONCLUSIONS: Lower COI is associated with longer length of stay and higher early postoperative mortality. Risk factors identified including Spanish language, food/housing insecurity, and parental literacy serve as potential intervention targets.

Clinical risk prediction score for postoperative accelerated junctional rhythm and junctional ectopic tachycardia in children with congenital heart disease.

BACKGROUND: Accelerated junctional rhythm (AJR) and junctional ectopic tachycardia (JET) are common postoperative arrhythmias associated with morbidity/mortality. Studies suggest that pre- or intraoperative treatment may improve outcomes, but patient selection remains a challenge. OBJECTIVES: The purpose of this study was to describe contemporary outcomes of postoperative AJR/JET and develop a risk prediction score to identify patients at highest risk. METHODS: This was a retrospective cohort study of children aged 0-18 years undergoing cardiac surgery (2011-2018). AJR was defined as usual complex tachycardia with ≥1:1 ventricular-atrial association and junctional rate >25th percentile of sinus rate for age but <170 bpm, whereas JET was defined as a rate >170 bpm. A risk prediction score was developed using random forest analysis and logistic regression. RESULTS: Among 6364 surgeries, AJR occurred in 215 (3.4%) and JET in 59 (0.9%). Age, heterotaxy syndrome, aortic cross-clamp time, ventricular septal defect closure, and atrioventricular canal repair were independent predictors of AJR/JET on multivariate analysis and included in the risk prediction score. The model accurately predicted the risk of AJR/JET with a C-index of 0.72 (95% confidence interval 0.70-0.75). Postoperative AJR and JET were associated with prolonged intensive care unit and hospital length of stay, but not with early mortality. CONCLUSION: We describe a novel risk prediction score to estimate the risk of postoperative AJR/JET permitting early identification of at-risk patients who may benefit from prophylactic treatment.

Conduction mapping during complex congenital heart surgery: Creating a predictive model of conduction anatomy.

OBJECTIVES: The study objectives were to report on a growing experience of conduction system mapping during complex congenital heart surgery and create a predictive model of conduction anatomy. METHODS: Patients undergoing complex cardiac repair with conduction mapping were studied. Intraoperative mapping used a multielectrode catheter to collect His bundle electrograms in the open, decompressed, beating heart. Patient anatomy, operative details, His bundle location, and postoperative conduction status were analyzed. By using classification and regression tree analysis, a predictive model of conduction location was created. RESULTS: A total of 109 patients underwent mapping. Median age and weight were 1.8 years (range, 0.2-14.9) and 10.8 kg (range, 3.5-50.4), respectively. Conduction was identified in 96% (105/109). Median mapping time was 6 minutes (range, 2-33). Anatomy included atrioventricular canal defect, double outlet right ventricle, complex transposition of the great arteries, and multiple ventricular septal defects. By classification and regression tree analysis, ventricular looping and visceroatrial situs were the greatest discriminators of conduction location. A total of 94 of 105 patients (89.5%) were free of complete heart block. Only 1 patient (2.9%) with heterotaxy syndrome developed complete heart block. CONCLUSIONS: The precise anatomic location of the conduction system in patients with complex congenital heart defects can be difficult for the surgeon to accurately predict. Intraoperative conduction mapping enables localization of the His bundle and adds to our understanding of the anatomic factors associated with conduction location. Predictive modeling of conduction anatomy may build on what is already known about the conduction system and help surgeons to better anticipate conduction location preoperatively and intraoperatively.

Pediatric Electrophysiology Device Needs: A Survey from the Pediatric and Congenital Electrophysiology Society Taskforce on Pediatric-Specific Devices.

Background There are few US Food and Drug Administration (FDA)-approved devices specifically aimed at the pediatric patient with arrhythmia. This has led to a high off-label utilization of devices in this vulnerable population. The Pediatric and Congenital Electrophysiology Society (PACES), the international organization representing pediatric and congenital heart disease arrhythmia specialists, developed a task force to comprehensively address device development issues relevant to pediatric patients with congenital arrhythmia. Methods and Results As a first step, the taskforce developed a 26-question survey for the pediatric arrhythmia community to assess providers' understanding of the FDA approval process, specifically in regard to pediatric labeling. There were 92/211 respondents (44%) with a >90% completion rate. The vast majority of respondents believed there was a paucity of devices available for children (96%). More than 60% of respondents stated that they did not understand the FDA regulatory process and were not aware of whether the devices they used were labeled for pediatric use. Conclusions Pediatric electrophysiologists are keenly aware of the deficit of available pediatric devices for their patients. The majority do not understand the FDA approval process and could benefit from additional educational resources regarding this. A collaborative forum including PACES, FDA, patients and their families, and Industry would be an important next step in clarifying opportunities and priorities to serve this vulnerable population.

Radiofrequency Catheter Ablation for Pediatric Atrioventricular Nodal Reentrant Tachycardia: Impact of Age on Procedural Methods and Durable Success.

Background Catheter-based slow-pathway modification (SPM) is the treatment of choice for symptomatic atrioventricular nodal reentrant tachycardia (AVNRT). We sought to investigate the interactions between patient age and procedural outcomes in pediatric patients undergoing catheter-based SPM for AVNRT. Methods and Results A retrospective cohort study was performed, including consecutive patients undergoing acutely successful SPM for AVNRT from 2008 to 2017. Those with congenital heart disease, cardiomyopathy, and accessory pathways were excluded. Patients were stratified by age quartile at time of SPM. The primary outcome was AVNRT recurrence. A total of 512 patients underwent successful SPM for AVNRT. Age quartile 1 had 129 patients with a median age and weight of 8.9 years and 30.6 kg, respectively. Radiofrequency energy was used in 98% of cases. Follow-up was available in 447 (87%) patients with a median duration of 0.8 years (interquartile range, 0.2-2.5 years). AVNRT recurred in 22 patients. Multivariable Cox proportional hazard modeling identified atypical AVNRT (hazard ratio [HR], 5.83; 95% CI, 2.01-16.96; P=0.001), dual atrioventricular nodal only (HR, 4.09; 95% CI, 1.39-12.02; P=0.011), total radiofrequency lesions (HR, 1.06 per lesion; 95% CI, 1.01-1.12; P=0.032), and the use of a long sheath (HR, 3.52; 95% CI, 1.23-10.03; P=0.010) as predictors of AVNRT recurrence; quartile 1 patients were not at higher risk of recurrence (HR, 0.45; 95% CI, 0.10-1.97; P=0.29). Complete heart block requiring permanent pacing occurred in one quartile 2 patient at 14.9 years of age. Conclusions Pediatric AVNRT can be treated with radiofrequency-SPM with high procedural efficacy and minimal risk of complications, including heart block. Atypical AVNRT and dual atrioventricular nodal physiology without inducible tachycardia remain challenging substrates.

Intraoperative conduction mapping in complex congenital heart surgery.

Objective: Postoperative heart block is a significant problem in congenital heart surgery because of the unpredictability and variability of conduction tissue location in complex congenital heart defects. A novel technique for intraoperative conduction system mapping during complex congenital heart surgery is described. Methods: Intraoperative conduction system mapping was performed utilizing a high-density multielectrode grid catheter to collect intracardiac electrograms on open, beating hearts during repair of complex congenital heart defects. Electrograms were interpreted by electrophysiologists, and conduction tissue location was communicated in real time to the surgeon. After localizing conduction tissue, the heart was arrested and the repair was completed taking care to avoid injury to the mapped conduction system. Results: Two patients with complex heterotaxy syndrome underwent intraoperative conduction mapping during biventricular repair. Mapping accurately identified the location of conduction tissue thereby enabling avoidance of conduction system injury during surgery. Notably, conduction was unexpectedly found to be located inferiorly in a patient with L-looped ventricles. Successful biventricular repair was accomplished in both patients without injury to the conduction system. Conclusions: Intraoperative conduction mapping can effectively localize the conduction system during surgery and enable the surgeon to avoid its injury. This can lower the risk of heart block requiring pacemaker in children undergoing complex congenital heart surgery.

Lead Extraction at a Pediatric/Congenital Heart Disease Center: The Importance of Patient Age at Implant.

OBJECTIVES: This study sought to evaluate the safety and efficacy of transvenous lead extraction (TLE) at a single pediatric/congenital heart disease (CHD) center. BACKGROUND: Data on TLE in pediatric and CHD patients are limited. METHODS: Retrospective cohort study evaluating TLE from 2008 to 2019. RESULTS: A total of 113 patients underwent TLE with 162 leads removed (including 38 high-voltage leads). Median age at lead implantation was 13 years (range 0.6-61.8 years), with a median age at extraction of 21.6 years (6.4-64.3 years). Median lead age was 7.2 years (1.0-35.3 years). Successful extraction occurred in 110 (97%) patients, 159 (98%) leads. Complex extraction was needed for 120 leads; 52 (44%) using laser alone, 27 (23%) mechanical sheath alone, and 21 (18%) using both. Femoral extraction was used for 19 (16%) leads. Risk factors for complex extraction were ≥2 leads extracted (odds ratio: 3.36; 95% confidence interval [CI]: 1.2-9.36; P = 0.021), lead within the right ventricle (odds ratio: 2.8; 95% CI: 1.2-6.5; P = 0.017), and a combination of younger patient age at implant and older lead age at extraction, with patients ≤12 years of age at implant and leads ≥7 years of age having an odds ratio: of 10.1 (95% CI: 2.21-45.9; P = 0.003). Major complications occurred in 5 (4.4%) of patients, with no mortality, but a high incidence of tricuspid valve injury. CONCLUSIONS: TLE can be performed successfully and safely in a pediatric and CHD center. Patient age at lead implantation, not age at extraction, is an important predictor of needing a complex extraction, with younger patients at implant and older leads at extraction having the highest risk.

Activity During the COVID-19 Pandemic in Children with Cardiac Rhythm Management Devices.

Decreased physical activity is associated with cardiovascular, metabolic and mental health disease. While decreases in physical activity during the COVID-19 pandemic have been described in the general population, there is a paucity of data regarding children with underlying cardiovascular disease. We hypothesized there would be a decrease in physical activity at the onset of the COVID-19 pandemic. Performed a single-center, retrospective cohort study of children aged < 19 years with cardiac rhythm management devices. Patients were included if they had device-measured physical activity data from > 80% of dates from February 3, 2020 through June 30, 2020. Patients with significant neurologic/neuromuscular disease were excluded. We identified 144 patients with a median age of 15.4 years. 47% were female. 34% had congenital heart disease, 20% had cardiomyopathy, 19% had an inherited arrhythmia syndrome and 5% had atrioventricular block without congenital heart disease. 47% of patients had an implantable loop recorder, 29% had a permanent pacemaker and 24% had an implantable cardioverter-defibrillator. We observed a significant decrease in device-measured physical activity from baseline (February 3-March 9), with up to a 21% decrease in physical activity during mid-March through early May. Activity levels returned to pre-pandemic levels in June. Physical activity sharply declined in children with cardiac rhythm management devices at the onset of the COVID-19 pandemic. These data highlight the importance of finding strategies to maintain physical activity during the current pandemic and future public health crises.