Quantitative Prediction of Right Ventricular Size and Function From the ECG.

BACKGROUND: Right ventricular ejection fraction (RVEF) and end-diastolic volume (RVEDV) are not readily assessed through traditional modalities. Deep learning-enabled ECG analysis for estimation of right ventricular (RV) size or function is unexplored. METHODS AND RESULTS: We trained a deep learning-ECG model to predict RV dilation (RVEDV >120 mL/m2), RV dysfunction (RVEF ≤40%), and numerical RVEDV and RVEF from a 12-lead ECG paired with reference-standard cardiac magnetic resonance imaging volumetric measurements in UK Biobank (UKBB; n=42 938). We fine-tuned in a multicenter health system (MSHoriginal [Mount Sinai Hospital]; n=3019) with prospective validation over 4 months (MSHvalidation; n=115). We evaluated performance with area under the receiver operating characteristic curve for categorical and mean absolute error for continuous measures overall and in key subgroups. We assessed the association of RVEF prediction with transplant-free survival with Cox proportional hazards models. The prevalence of RV dysfunction for UKBB/MSHoriginal/MSHvalidation cohorts was 1.0%/18.0%/15.7%, respectively. RV dysfunction model area under the receiver operating characteristic curve for UKBB/MSHoriginal/MSHvalidation cohorts was 0.86/0.81/0.77, respectively. The prevalence of RV dilation for UKBB/MSHoriginal/MSHvalidation cohorts was 1.6%/10.6%/4.3%. RV dilation model area under the receiver operating characteristic curve for UKBB/MSHoriginal/MSHvalidation cohorts was 0.91/0.81/0.92, respectively. MSHoriginal mean absolute error was RVEF=7.8% and RVEDV=17.6 mL/m2. The performance of the RVEF model was similar in key subgroups including with and without left ventricular dysfunction. Over a median follow-up of 2.3 years, predicted RVEF was associated with adjusted transplant-free survival (hazard ratio, 1.40 for each 10% decrease; P=0.031). CONCLUSIONS: Deep learning-ECG analysis can identify significant cardiac magnetic resonance imaging RV dysfunction and dilation with good performance. Predicted RVEF is associated with clinical outcome.

E-Health: A Game Changer in Fetal and Neonatal Cardiology?

Technological advancements have greatly impacted the healthcare industry, including the integration of e-health in pediatric cardiology. The use of telemedicine, mobile health applications, and electronic health records have demonstrated a significant potential to improve patient outcomes, reduce healthcare costs, and enhance the quality of care. Telemedicine provides a useful tool for remote clinics, follow-up visits, and monitoring for infants with congenital heart disease, while mobile health applications enhance patient and parents' education, medication compliance, and in some instances, remote monitoring of vital signs. Despite the benefits of e-health, there are potential limitations and challenges, such as issues related to availability, cost-effectiveness, data privacy and security, and the potential ethical, legal, and social implications of e-health interventions. In this review, we aim to highlight the current application and perspectives of e-health in the field of fetal and neonatal cardiology, including expert parents' opinions.

Neighborhood Childhood Opportunity, Race/Ethnicity, and Surgical Outcomes in Children With Congenital Heart Disease.

BACKGROUND: Racial and ethnic disparities in outcomes for children with congenital heart disease (CHD) coexist with disparities in educational, environmental, and economic opportunity. OBJECTIVES: We sought to determine the associations between childhood opportunity, race/ethnicity, and pediatric CHD surgery outcomes. METHODS: Pediatric Health Information System encounters aged <18 years from 2016 to 2022 with International Classification of Diseases-10th edition codes for CHD and cardiac surgery were linked to ZIP code-level Childhood Opportunity Index (COI), a score of neighborhood educational, environmental, and socioeconomic conditions. The associations of race/ethnicity and COI with in-hospital surgical death were modeled with generalized estimating equations and formal mediation analysis. Neonatal survival after discharge was modeled by Cox proportional hazards. RESULTS: Of 54,666 encounters at 47 centers, non-Hispanic Black (Black) (OR: 1.20; P = 0.01), Asian (OR: 1.75; P < 0.001), and Other (OR: 1.50; P < 0.001) groups had increased adjusted mortality vs non-Hispanic Whites. The lowest COI quintile had increased in-hospital mortality in unadjusted and partially adjusted models (OR: 1.29; P = 0.004), but not fully adjusted models (OR: 1.14; P = 0.13). COI partially mediated the effect of race/ethnicity on in-hospital mortality between 2.6% (P = 0.64) and 16.8% (P = 0.029), depending on model specification. In neonatal multivariable survival analysis (n = 13,987; median follow-up: 0.70 years), the lowest COI quintile had poorer survival (HR: 1.21; P = 0.04). CONCLUSIONS: Children in the lowest COI quintile are at risk for poor outcomes after CHD surgery. Disproportionally increased mortality in Black, Asian, and Other populations may be partially mediated by COI. Targeted investment in low COI neighborhoods may improve outcomes after hospital discharge. Identification of unmeasured factors to explain persistent risk attributed to race/ethnicity is an important area of future exploration.

Pulmonary Complications in Patients With Fontan Circulation: JACC Review Topic of the Week.

The Fontan operation has resulted in significant improvement in survival of patients with single ventricle physiology. As a result, there is a growing population of individuals with Fontan physiology reaching adolescence and adulthood. Despite the improved survival, there are long-term morbidities associated with the Fontan operation. Pulmonary complications are common and may contribute to both circulatory and pulmonary insufficiency, leading ultimately to Fontan failure. These complications include restrictive lung disease, sleep abnormalities, plastic bronchitis, and cyanosis. Cyanosis post-Fontan procedure can be attributed to multiple causes including systemic to pulmonary venous collateral channels and pulmonary arteriovenous malformations. This review presents the unique cardiopulmonary interactions in the Fontan circulation. Understanding the cardiopulmonary interactions along with improved recognition and treatment of pulmonary abnormalities may improve the long-term outcomes in this growing patient population. Interventions focused on improving pulmonary function including inspiratory muscle training and endurance training have shown a promising effect post-Fontan procedure.

Quantitative prediction of right ventricular and size and function from the electrocardiogram.

Background: Right ventricular ejection fraction (RVEF) and end-diastolic volume (RVEDV) are not readily assessed through traditional modalities. Deep-learning enabled 12-lead electrocardiogram analysis (DL-ECG) for estimation of RV size or function is unexplored. Methods: We trained a DL-ECG model to predict RV dilation (RVEDV>120 mL/m2), RV dysfunction (RVEF≤40%), and numerical RVEDV/RVEF from 12-lead ECG paired with reference-standard cardiac MRI (cMRI) volumetric measurements in UK biobank (UKBB; n=42,938). We fine-tuned in a multi-center health system (MSHoriginal; n=3,019) with prospective validation over 4 months (MSHvalidation; n=115). We evaluated performance using area under the receiver operating curve (AUROC) for categorical and mean absolute error (MAE) for continuous measures overall and in key subgroups. We assessed association of RVEF prediction with transplant-free survival with Cox proportional hazards models. Results: Prevalence of RV dysfunction for UKBB/MSHoriginal/MSHvalidation cohorts was 1.0%/18.0%/15.7%, respectively. RV dysfunction model AUROC for UKBB/MSHoriginal/MSHvalidation cohorts was 0.86/0.81/0.77, respectively. Prevalence of RV dilation for UKBB/MSHoriginal/MSHvalidation cohorts was 1.6%/10.6%/4.3%. RV dilation model AUROC for UKBB/MSHoriginal/MSHvalidation cohorts 0.91/0.81/0.92, respectively. MSHoriginal MAE was RVEF=7.8% and RVEDV=17.6 ml/m2. Performance was similar in key subgroups including with and without left ventricular dysfunction. Over median follow-up of 2.3 years, predicted RVEF was independently associated with composite outcome (HR 1.37 for each 10% decrease, p=0.046). Conclusions: DL-ECG analysis can accurately identify significant RV dysfunction and dilation both overall and in key subgroups. Predicted RVEF is independently associated with clinical outcome.

Management of Heart Failure With Arrhythmia in Adults With Congenital Heart Disease: JACC State-of-the-Art Review.

Together, heart failure and arrhythmia represent the most important cardiovascular sources of morbidity and mortality among adults with congenital heart disease (ACHDs). Although traditionally conceptualized as operating within 2 distinct clinical silos, these scenarios frequently coexist within the same individual; consequently the mechanistic, therapeutic, and prognostic overlap between them demands increased recognition. In fact, given the near ubiquity of heart failure and arrhythmia among ACHDs, there is perhaps no other arena within cardiology where this critical intersection is more frequently observed. Optimal care for ACHDs therefore requires a heightened awareness of the relevant interactions as well as the pharmacologic and interventional resources that are increasingly available to the treating cardiologist. This review explores and highlights the overlap between these 2 fields to recommend a parallel, yet interactive, multidisciplinary approach to clinical management. Congenital heart disease categories are broken down into their archetypal subtypes to highlight subtleties of the pathophysiology, evaluation, and therapeutic approach.

Familial Recurrence Patterns in Congenitally Corrected Transposition of the Great Arteries: An International Study.

BACKGROUND: Congenitally corrected transposition of the great arteries (ccTGA) is a rare disease of unknown cause. We aimed to better understand familial recurrence patterns. METHODS: An international, multicentre, retrospective cohort study was conducted in 29 tertiary hospitals in 6 countries between 1990 and 2018, entailing investigation of 1043 unrelated ccTGA probands. RESULTS: Laterality defects and atrioventricular block at diagnosis were observed in 29.9% and 9.3%, respectively. ccTGA was associated with primary ciliary dyskinesia in 11 patients. Parental consanguinity was noted in 3.4% cases. A congenital heart defect was diagnosed in 81 relatives from 69 families, 58% of them being first-degree relatives, including 28 siblings. The most prevalent defects in relatives were dextro-transposition of the great arteries (28.4%), laterality defects (13.6%), and ccTGA (11.1%); 36 new familial clusters were described, including 8 pedigrees with concordant familial aggregation of ccTGA, 19 pedigrees with familial co-segregation of ccTGA and dextro-transposition of the great arteries, and 9 familial co-segregation of ccTGA and laterality defects. In one family co-segregation of ccTGA, dextro-transposition of the great arteries and heterotaxy syndrome in 3 distinct relatives was found. In another family, twins both displayed ccTGA and primary ciliary dyskinesia. CONCLUSIONS: ccTGA is not always a sporadic congenital heart defect. Familial clusters as well as evidence of an association between ccTGA, dextro-transposition of the great arteries, laterality defects and in some cases primary ciliary dyskinesia, strongly suggest a common pathogenetic pathway involving laterality genes in the pathophysiology of ccTGA.

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.

Multisystem Inflammatory Syndrome in Children Associated with Severe Acute Respiratory Syndrome Coronavirus 2 Infection (MIS-C): A Multi-institutional Study from New York City.

OBJECTIVE: To assess clinical characteristics and outcomes of severe acute respiratory syndrome coronavirus 2-associated multisystem inflammatory syndrome in children (MIS-C). STUDY DESIGN: Children with MIS-C admitted to pediatric intensive care units in New York City between April 23 and May 23, 2020, were included. Demographic and clinical data were collected. RESULTS: Of 33 children with MIS-C, the median age was 10 years; 61% were male; 45% were Hispanic/Latino; and 39% were black. Comorbidities were present in 45%. Fever (93%) and vomiting (69%) were the most common presenting symptoms. Depressed left ventricular ejection fraction was found in 63% of patients with median ejection fraction of 46.6% (IQR, 39.5-52.8). C-reactive protein, procalcitonin, d-dimer, and pro-B-type natriuretic peptide levels were elevated in all patients. For treatment, intravenous immunoglobulin was used in 18 (54%), corticosteroids in 17 (51%), tocilizumab in 12 (36%), remdesivir in 7 (21%), vasopressors in 17 (51%), mechanical ventilation in 5 (15%), extracorporeal membrane oxygenation in 1 (3%), and intra-aortic balloon pump in 1 (3%). The left ventricular ejection fraction normalized in 95% of those with a depressed ejection fraction. All patients were discharged home with median duration of pediatric intensive care unit stay of 4.7 days (IQR, 4-8 days) and a hospital stay of 7.8 days (IQR, 6.0-10.1 days). One patient (3%) died after withdrawal of care secondary to stroke while on extracorporeal membrane oxygenation. CONCLUSIONS: Critically ill children with coronavirus disease-2019-associated MIS-C have a spectrum of severity broader than described previously but still require careful supportive intensive care. Rapid, complete clinical and myocardial recovery was almost universal.

Can the 12-lead ECG distinguish RVOT from aortic cusp PVCs in pediatric patients?

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

Newborn With Severely Depressed Left Ventricular Function: Acute Myocardial Infarction in a Newborn.

We describe a rare case of spontaneous coronary artery thrombosis in a newborn leading to rapid severe ventricular dysfunction. Early diagnosis is critical and management strategies are varied including hemodynamic support with extracorporeal membrane oxygenation, systemic/local thrombolytic therapy with tissue plasminogen activator, or surgical thrombectomy. (Level of Difficulty: Advanced.).

"If at first you don't succeed": repeat ablations in young patients with supraventricular tachycardia.

PURPOSE: Success rates for catheter ablation of supraventricular tachycardia (SVT) in the young exceed 90%. While studies have described reasons for initial ablation failure, less is known about outcomes of repeat ablation attempts. The purpose of this study was to report acute and mid-term success rates for second ablation attempts in young patients, as well as to analyze factors that may affect these outcomes. METHODS: Retrospective single-center study of all patients undergoing a second ablation attempt for WPW (Wolff-Parkinson-White) or SVT from 2008 to 2017. Inclusion criteria are all patients < 21 years old at the time of their first ablation who underwent a second ablation attempt. An intention to treat analysis was performed. RESULTS: Fifty-five patients met inclusion criteria, with a median age of 15 years (IQR 12-16). The most common arrhythmia mechanisms at repeat procedure were single accessory pathways (n = 32, 58%) and AVNRT (n = 14, 25%). Six patients (11%) were found to have a different SVT mechanism than at initial ablation. Acute success at repeat ablation was achieved in 48 patients (87%). At mid-term follow-up (10.5 months, IQR 0.6-25), four patients (8% of acute successes) experienced SVT recurrence. The overall success rate of repeat ablations, accounting for acute and mid-term failures, was 80%. CONCLUSIONS: In this report of 55 young patients who underwent repeat ablation for WPW and/or SVT, acute and mid-term success rates were 87% and 80%, respectively. These data may help inform decision-making when caring for patients with persistent or recurrent SVT after an initial ablation attempt.

Validation of a novel automated signal analysis tool for ablation of Wolff-Parkinson-White Syndrome.

BACKGROUND: In previous pilot work we demonstrated that a novel automated signal analysis tool could accurately identify successful ablation sites during Wolff-Parkinson-White (WPW) ablation at a single center. OBJECTIVE: We sought to validate and refine this signal analysis tool in a larger multi-center cohort of children with WPW. METHODS: A retrospective review was performed of signal data from children with WPW who underwent ablation at two pediatric arrhythmia centers from 2008-2015. All patients with WPW ≤ 21 years who underwent invasive electrophysiology study and ablation with ablation signals available for review were included. Signals were excluded if temperature or power delivery was inadequate or lesion time was < 5 seconds. Ablation lesions were reviewed for each patient. Signals were classified as successful if there was loss of antegrade and retrograde accessory pathway (AP) conduction or unsuccessful if ablation did not eliminate AP conduction. Custom signal analysis software analyzed intracardiac electrograms for amplitudes, high and low frequency components, integrated area, and signal timing components to create a signal score. We validated the previously published signal score threshold 3.1 in this larger, more diverse cohort and explored additional scoring options. Logistic regression with lasso regularization using Youden's index criterion and a cost-benefit criterion to identify thresholds was considered as a refinement to this score. RESULTS: 347 signals (141 successful, 206 unsuccessful) in 144 pts were analyzed [mean age 13.2 ± 3.9 years, 96 (67%) male, 66 (45%) left sided APs]. The software correctly identified the signals as successful or unsuccessful in 276/347 (80%) at a threshold of 3.1. The performance of other thresholds did not significantly improve the predictive ability. A signal score threshold of 3.1 provided the following diagnostic accuracy for distinguishing a successful from unsuccessful signal: sensitivity 83%, specificity 77%, PPV 71%, NPV 87%. CONCLUSIONS: An automated signal analysis software tool reliably distinguished successful versus unsuccessful ablation electrograms in children with WPW when validated in a large, diverse cohort. Refining the tools using an alternative threshold and statistical method did not improve the original signal score at a threshold of 3.1. This software was effective across two centers and multiple operators and may be an effective tool for ablation of WPW.

Incidence of Echocardiographic Abnormalities Following Pediatric SVT Ablation: Comparison of Cases Utilizing Fluoroscopy Alone to Cases with Adjunctive 3D Electroanatomic Mapping.

There are few data on the incidence of echocardiographic (echo) abnormalities following catheter ablation in children in the era of 3D mapping. Wide practice variation exists regarding routine post-ablation echo. We hypothesized a low incidence of clinically significant echo abnormalities following SVT ablation in otherwise healthy children. Single center data from 2009 to 2015 were reviewed; routine post-ablation echo was standard practice. Cases were categorized as utilizing fluoroscopy alone (FLUORO) or 3D mapping with a low fluoroscopic protocol (CARTO3). Congenital heart disease was excluded. Outcomes of interest included new valvular abnormalities, pericardial effusions, and wall motion abnormalities. Findings were compared to baseline studies when available and classified as normal/unchanged, clinically insignificant, or clinically significant. Outcomes were compared between FLUORO and CARTO3 groups. Of 347 ablations, 319 (92%) underwent post-procedural echo: 57% male; 55% FLUORO; mean age 13.4 ± 3.6 years. The most common ablation target was an accessory pathway (AP) in 66% (n = 144 WPW, 66 concealed), followed by AVNRT in 32% (n = 102). Radiofrequency (RF) energy was utilized in 82% (n = 262). Post-ablation echos were normal in 81% (n = 259). Clinically insignificant findings were seen in 18% (n = 58), most commonly trivial-small pericardial effusions in 11% (n = 34). Two significant findings required additional follow-up or treatment. There were no cases of wall motion abnormalities or clinically significant effusions. There were no differences in frequency of echo abnormalities between the FLUORO and CARTO3 groups. Clinically significant echocardiographic abnormalities are rare following SVT ablation in children with structurally normal hearts, independent of the use of 3D mapping.

A Prospective Assessment of Optimal Mechanical Ventilation Parameters for Pediatric Catheter Ablation.

Catheter stability, an important factor in ablation success, is affected by ventilation. Optimal ventilation strategies for pediatric catheter ablation are not known. We hypothesized that small tidal volume and positive end-expiratory pressure are associated with reduced ablation catheter movement at annular positions. Subjects aged 5-25 years undergoing ablation for supraventricular tachycardia (SVT) or WPW at two centers from March 2015 to September 2016 were prospectively enrolled and randomized to receive mechanical ventilation with either positive end-expiratory pressure of 5 cm H2O (PEEP) or 0 cm H2O (ZEEP). Movement of the ablation catheter tip at standard annular positions was measured using 3D electroanatomic mapping systems under two conditions: small tidal volume (STV) (3-5 mL/kg) or large TV (LTV) (6-8 mL/kg). 58 subjects (mean age 13.8 years) were enrolled for a total of 266 separate observations of catheter movement. STV ventilation was associated with significantly reduced catheter movement, compared to LTV at all positions (right posteroseptal: 2.5 ± 1.4 vs. 5.2 ± 3.1 mm, p < 0.0001; right lateral: 2.7 ± 1.6 vs. 6.3 ± 3.5 mm, p < 0.0001; left lateral: 1.8 ± 1.0 vs. 4.3 ± 1.9 mm, p < 0.0001). The presence or absence of PEEP had no effect on catheter movement. In multivariable analysis, STV was associated with a 3.1-mm reduction in movement (95% CI 2.6-3.5, p < 0.0001), adjusting for end-expiratory pressure, annular location, and patient size. We conclude that STV ventilation is associated with reduced ablation catheter movement compared to a LTV strategy, independent of PEEP and annular position.

Assessment of a novel radiation reduction protocol for pediatric and adult congenital device implantation.

PURPOSE: Device implantation requires fluoroscopic guidance, which carries inherent risks of ionizing radiation. We evaluated the impact of a low-dose fluoroscopic protocol on radiation exposure during device implantation. METHODS: All patients who underwent pacemaker or ICD implantation with new transvenous leads from July 2011 to January 2018 were included. A novel ALARA protocol consisting of ultra-low frame rates (2-3 frames/s), low dose/frame (6-18 mGy/frame), and use of the "air-gap" technique in patients < 20 kg was employed. Demographics, procedural data, and radiation exposure levels were collected and analyzed. RESULTS: Thirty patients underwent device implantation without additional catheterization, electrophysiology study, or ablation procedure (median age 15 years; range 5-50) with a total of 43 leads placed. Forty-seven percent of patients had a primary rhythm disturbance, 33% had cardiomyopathy, and 20% had congenital heart disease. Fifty percent were pacemakers (53% dual-chamber, 27% ventricle, 20% atrial) and 50% of devices implanted were ICDs (87% single-chamber). All implants were acutely successful with acceptable atrial and ventricular sensing and capture thresholds. The median fluoroscopy time was 11.5 min (inter-quartile range (IQR) 8.0-18.2), median air kerma dose 4.0 mGy (IQR 2.5-19.5), and median dose-area product 27.8 µGy/m2 (IQR 17.1-106.5). Median implant procedure time was 133 min. One patient required revision secondary to device migration without lead derangement 2 days post-procedure. CONCLUSIONS: Use of a novel fluoroscopic protocol may help decrease radiation exposure to patients and staff without affecting efficacy or risk. These data may represent benchmarks against which future device implantation procedures can be compared.

Ultrasound-guided axillary venous access for pediatric and adult congenital lead implantation.

BACKGROUND: Axillary venous access with ultrasound guidance for pediatric transvenous lead implantation may reduce risks for pneumothorax and hemothorax. The objective was to retrospectively evaluate ultrasound-guided axillary vein access as an alternative to the subclavian approach. METHODS: The technique consists of ultrasonographic identification of the axillary vein at the deltopectoral groove after initial contrast venography. A micropuncture kit is used for initial ultrasound-guided percutaneous access with fluoroscopic confirmation of wire position. Pocket creation is performed, and sheath insertion and lead implantation proceed as usual. Demographic, procedural, and radiation exposure data were collected and analyzed. RESULTS: Sixteen patients (median age = 13 years, 8-50 years; median weight = 56 kg, 29-77 kg) underwent lead implantation; two additional patients required fluoroscopy due to poor acoustic windows (89% success). Fifteen of 21 leads (71%) were ventricular; 50% of implants were pacemakers, and 31% were dual chamber. Median time to venous access was 13 min (interquartile range (IQR) = 9.25-20.25) and median implant procedure time was 156 min (IQR = 112-172). Median fluoroscopy time was 18.0 min (IQR = 11.9-29.6), median air kerma was 9.0 mGy (IQR = 3.0-28.5), and median dose-area product was 30.2 Gy-cm2 (IQR = 16.1-234.5). One patient required generator pocket revision 2 days postprocedure without lead dislodgement. There were no other complications encountered. CONCLUSIONS: Transvenous pacemaker and implantable cardioverter-defibrillator lead implantation in the pediatric and adult congenital population through ultrasound-guided axillary venous access is safe and efficacious. This technique may provide a low-risk alternative for vascular access for pediatric implantation procedures.

Electrocardiograms in Healthy North American Children in the Digital Age.

BACKGROUND: Interpretation of pediatric ECGs is limited by lack of accurate sex- and race-specific normal reference values obtained with modern technology for all ages. We sought to obtain contemporary digital ECG measurements in healthy children from North America, to evaluate the effects of sex and race, and to compare our results to commonly used published datasets. METHODS: Digital ECGs (12-lead) were retrospectively collected for children ≤18 years old with normal echocardiograms at 19 centers in the Pediatric Heart Network. Patients were classified into 36 groups: 6 age, 2 sex, and 3 race (white, black, and other/mixed) categories. Standard intervals and amplitudes were measured; mean±SD and 2nd/98th percentiles were determined by age group, sex, and race. For each parameter, multivariable analysis, stratified by age, was conducted using sex and race as predictors. Parameters were compared with 2 large pediatric ECG data sets. RESULTS: Among ECGs from 2400 children, significant differences were found by sex and race categories. The corrected QT interval in lead II was greater for girls compared with boys for age groups ≥3 years (P≤0.03) and for whites compared with blacks for age groups ≥12 years (P<0.05). The R wave amplitude in V6 was greater for boys compared with girls for age groups ≥12 years (P<0.001), for blacks compared with white or other race categories for age groups ≥3 years (P≤0.006), and greater compared with a commonly used public data set for age groups ≥12 years (P<0.0001). CONCLUSIONS: In this large, diverse cohort of healthy children, most ECG intervals and amplitudes varied by sex and race. These differences have important implications for interpreting pediatric ECGs in the modern era when used for diagnosis or screening, including thresholds for left ventricular hypertrophy.