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Background:Electroanatomic mapping systems are increasingly used during ablations to decrease the need for fluoroscopy and therefore radiation exposure. For left-sided arrhythmias, transseptal puncture is a common procedure performed to gain access to the left side of the heart. We aimed to demonstrate the radiation exposure associated with transseptal puncture.Methods:Data were retrospectively collected from the Catheter Ablation with Reduction or Elimination of Fluoroscopy registry. Patients with left-sided accessory pathway-mediated tachycardia, with a structurally normal heart, who had a transseptal puncture, and were under 22 years of age were included. Those with previous ablations, concurrent diagnostic or interventional catheterisation, and missing data for fluoroscopy use or procedural outcomes were excluded. Patients with a patent foramen ovale who did not have a transseptal puncture were selected as the control group using the same criteria. Procedural outcomes were compared between the two groups.Results:There were 284 patients in the transseptal puncture group and 70 in the patent foramen ovale group. The transseptal puncture group had a significantly higher mean procedure time (158.8 versus 131.4 minutes, p = 0.002), rate of fluoroscopy use (38% versus 7%, p < 0.001), and mean fluoroscopy time (2.4 versus 0.6 minutes, p < 0.001). The acute success and complication rates were similar.Conclusions:Performing transseptal puncture remains a common reason to utilise fluoroscopy in the era of non-fluoroscopic ablation. Better tools are needed to make non-fluoroscopic transseptal puncture more feasible.

Background:Catheter ablation is a safe and effective therapy for the treatment of supraventricular tachycardia in children. Current improvements in technology have allowed progressive reduction in radiation exposure associated with the procedure. To assess the impact of three-dimensional mapping, we compared acute procedural results collected from the Catheter Ablation with Reduction or Elimination of Fluoroscopy registry to published results from the Prospective Assessment after Pediatric Cardiac Ablation study.Methods:Inclusion and exclusion criteria from the Prospective Assessment after Pediatric Cardiac Ablation study were used as guidelines to select patient data from the Catheter Ablation with Reduction or Elimination of Fluoroscopy registry to compare acute procedural outcomes between cohorts. Outcomes assessed include procedural and fluoroscopy exposure times, success rates of procedure, and complications.Results:In 786 ablation procedures, targeting 498 accessory pathways and 288 atrioventricular nodal reentrant tachycardia substrates, average procedural time (156.5 versus 206.7 minutes, p < 0.01), and fluoroscopy time (1.2 versus 38.3 minutes, p < 0.01) were significantly shorter in the study group. Success rates for the various substrates were similar except for manifest accessory pathways which had a significantly higher success rate in the study group (96.4% versus 93.0%, p < 0.01). Major complication rates were significantly lower in the study group (0.3% versus 1.6%, p < 0.01).Conclusions:In a large, multicentre study, three-dimensional systems show favourable improvements in clinical outcomes in children undergoing catheter ablation of supraventricular tachycardia compared to the traditional fluoroscopic approach. Further improvements are anticipated as technology advances.

Background:Patients with CHD can be exposed to high levels of cumulative ionising radiation. Utilisation of electroanatomic mapping during catheter ablation leads to reduced radiation exposure in the general population but has not been well studied in patients with CHD. This study evaluated the radiation sparing benefit of using three-dimensional mapping in patients with CHD.Methods:Data were retrospectively collected from the Catheter Ablation with Reduction or Elimination of Fluoroscopy multi-institutional registry. Patients with CHD were selected. Those with previous ablations, concurrent diagnostic or interventional catheterisation and unknown arrhythmogenic foci were excluded. The control cohort was matched for operating physician, arrhythmia mechanism, arrhythmia location, weight and age. The procedure time, rate of fluoroscopy use, fluoroscopy time, procedural success, complications, and distribution of procedures per year were compared between the two groups.Results:Fifty-six patients with congenital heart disease and 56 matched patients without CHD were included. The mean total procedure time was significantly higher in patients with CHD (212.6 versus 169.5 minutes, p = 0.003). Their median total fluoroscopy time was 4.4 minutes (compared to 1.8 minutes), and their rate of fluoroscopy use was 23% (compared to 13%). The acute success and minor complication rates were similar and no major complications occurred.Conclusions:With the use of electroanatomic mapping during catheter ablation, fluoroscopy use can be reduced in patients with CHD. The majority of patients with CHD received zero fluoroscopy.

Background:Arrhythmias are common in the post-operative course of patients with hypoplastic left heart syndrome. We sought to determine the types, incidence, risk factors, and impact of arrhythmias in patients with HLHS and anatomic variants.Methods:We performed a retrospective chart review of 120 consecutive patients with HLHS and anatomical variants, who had single-ventricle palliation at our institution from January, 2006 to December, 2016.Results:A total of thirty-one patients (26%) had 37 episodes of arrhythmias over a median follow-up period of 3.5 years. Of the 37 episodes, 12 (32.4%) were ectopic atrial tachycardia, 9 (24.3%) were paroxysmal supraventricular tachycardia, 4 (10.8%) were junctional ectopic tachycardia, 5 (13.6%) were sinus node dysfunction, 3 (8.1%) were heart block, 2 (5.4%) were atrial flutter, and 2 (5.4%) were ventricular tachycardia. Twenty-four (65%) of the arrhythmias occurred at post-stage 1 surgery. Most (64.8%) of the arrhythmias were resolved. Arrhythmias that occurred at post-stage 1 surgery were more likely to resolve compared to post-stages 2 or 3 (p = 0.006). No anatomical, surgical, or clinical variables were associated with arrhythmia except for age (OR per unit decrease in age at stage 1 palliation: 1.12 (95% CI 1.003, 1.250); p = 0.0439). Arrhythmias were not associated with length of hospital stay or mortality.Conclusion:Arrhythmias are common in patients with HLHS and anatomic variants, with EAT and PSVT being the most common types. Arrhythmias were associated with younger age at surgery, but did not affect mortality or length of hospital stay.

The primary goal of this study was to evaluate the implant experience and midterm results of subcutaneous implantable cardioverter-defibrillators (S-ICDs) in pediatric patients and those with congenital heart disease.The S-ICD was developed to avoid the lead-related complications associated with transvenous systems. The absence of intravascular or intracardiac components offers potential advantages to pediatric patients and those with congenital heart disease.This international, multicenter, retrospective, standard-of-care study was conducted through the PediatricCongenital Electrophysiology Society. Complications at 30 and 360 days, inappropriate shocks, and delivery of appropriate therapy were assessed.The study included 115 patients with a median follow-up of 32 (19 to 52) months. Median age was 16.7 years (14.8 to 19.3 years), 29% were female, and 55% had a primary prevention indication. Underlying disease substrate was cardiomyopathy (40%), structural heart disease (32%), idiopathic ventricular fibrillation (16%), and channelopathy (13%). The complication rate was 7.8% at 30 days and 14.7% at 360 days. Overall, inappropriate shocks occurred in 15.6% of patients, with no single clinical characteristic reaching statistical significance. At implant, 97.9% of patients had successful first shock conversion with 96% requiring ≤65 J. Appropriate therapy was delivered to 11.2% of patients with an annual incidence of 3.9% and an acute first shock conversion success rate of 92.5%.This study found that in a heterogeneous population of pediatric patients and those with congenital heart disease, the S-ICD had comparable rates of complications, inappropriate shocks, and conversion efficacy compared with previously published studies on transvenous systems in similar populations.

Sudden death from aortic dissection of an ascending aortic aneurysm is an uncommon but important finding in all series of sudden death in young, apparently healthy athletes. Individuals at risk include those having any of a variety of conditions in which structural weakness of the ascending aorta predisposes to pathological dilation under prolonged periods of increased wall stress. These conditions include Marfan syndrome, Loeys–Dietz syndrome, bicuspid aortic valve, and the vascular form of Ehlers–Danlos syndrome. Diagnostic criteria, surveillance strategies, medical management, and surgical indications are discussed. Finally, the current recommendations for sports participation are provided.

Purpose of review Tetralogy of Fallot (TOF) carries a long-term risk of arrhythmias and sudden death after surgical repair. Risk stratification is still less accurate than desired. Recent findings Several factors have been studied as risk predictors for ventricular arrhythmias and sudden death. Clinical parameters include age at surgery, time since repair, types of previous surgeries, and symptoms such as syncope and palpitations. Electrocardiographic parameters that have been studied include QRS interval, ventricular arrhythmias assessed with Holter monitors, signal averaged ECG, QRS fragmentation, QRS vector magnitude, and microvolt T-wave alternans. Exercising testing has been shown to have prognostic significance. Ventricular function assessment with imaging studies including echocardiography and magnetic resonance imaging (MRI) plays a significant role. Invasive hemodynamic and electrophysiologic studies, in addition to assessment for inducible tachycardia, can provide information regarding the electroanatomic substrate of VT. Summary Risk stratification for TOF has improved over the last years with several clinical, electrocardiographic, imaging, and invasive electrophysiologic findings showing promise, but there still a lack of uniformity in approach between various investigators and reproducibility of findings is difficult in larger populations. With use of a combination of factors, a more informed decision can be made.

Dominic Abrams, MD, Sam Asirvatham, MD, Yaniv Bar-Cohen, MD, FAAP, FACC, FHRS, Andrew D. Blaufox, MD, FHRS, FACC, Bryan Cannon, MD, FHRS, John Clark, MD, Macdonald Dick, MD, FHRS, FACC, Anne Freter, MSN, FHRS, Naomi J. Kertesz, MD, FACC, FHRS, Joel A. Kirsh, MD, FRCP(C), FHRS, CEPS, John Kugler, MD, FAAC, FAAP, FAHA, Martin LaPage, MD, MS, FAAP, FHRS, CCDS, CEPS, Francis X. McGowan, MD, FAAP, Christina Y. Miyake, MD, Aruna Nathan, MBBS, FRCA, John Papagiannis, MD, FHRS, CEPS, Thomas Paul, MD, FHRS, FACC, Andreas Pflaumer, MD, FRACP, FCSANZ, CEPS, Allan C. Skanes, MD, FRCPC, William G. Stevenson, MD, FAHA, FHRS, FACC, Nicholas Von Bergen, Frank Zimmerman, MD, FAHA, FHRS

A pair of omphalo-thoracopagus twins was diagnosed with supraventricular tachycardia (SVT) on the first day of life. Twelve-lead electrocardiography was performed with leads placed on twin A ([Figure 1][1]). The 2:1 ratio of the 2 QRS populations was thought to be the result of SVT in twin A, with

Background Gain-of-function variants in the CACNA1C-encoded L-type calcium channel (LTCC, Cav1.2) cause type 8 long QT syndrome (LQT8). The pore region contains highly conserved glutamic acid (E) residues that collectively form the LTCC's selectivity filter. Here, we identified and characterized a pore-localizing missense variant, E1115K, that yielded a novel perturbation in the LTCC. Objective The purpose of this study was to determine whether CACNA1C-E1115K alters the LTCC's selectivity and is the substrate for the patient's LQTS. Methods The proband was a 14-year-old male with idiopathic QT prolongation and bradycardia. Genetic testing revealed a missense variant, CACNA1C-E1115K. The whole-cell patch clamp technique was used to measure CACNA1C-WT and -E1115K currents when heterologously expressed in TSA201 cells. Results The CACNA1C-E1115K channel exhibited no inward calcium current. Instead, robust cardiac transient outward potassium current (Ito)-like outward currents that were blocked significantly by nifedipine were measured when 2 mM/0.1 mM extracellular/intracellular CaCl2 or 4 mM/141 mM extracellular/intracellular KCl was applied. Furthermore, when 140 mM extracellular NaCl was applied, the CACNA1C-E1115K channel revealed both robust inward persistent Na+ currents with slower inactivation and outward currents, which were also nifedipine sensitive. In contrast, CACNA1C-WT revealed only a small inward persistent Na+ current without a robust outward current. Conclusion This CACNA1C-E1115K variant destroyed the LTCC's calcium selectivity and instead converted the mutant channel into a channel with a marked increase in sodium-mediated inward currents and potassium-mediated outward currents. Despite the anticipated 50% reduction in LTCC, the creation of a new population of channels with accentuated inward and outward currents represents the likely pathogenic substrates for the patient's LQTS and arrhythmia phenotype.

Technology transfer of gamification assets to non-leisure contexts such as the energy efficiency sector has become the “holy grail” of today's research and industrial efforts towards a more sustainable energy system. In the liberalized retail market context, electric utilities are gradually adopting new business models towards transitioning their conventional energy supply business to a more service-oriented model. This paper presents the H2020-funded SOCIALENERGY project, which develops a gaming and social network platform for educating energy consumers and virtual energy communities towards evolving EU energy markets' operation. The proposed S/W platform is modular by design and facilitates the easy, rich and deep communication among involved stakeholders from individual energy consumers and virtual energy communities, to utilities, policy makers, and even other indirect stakeholders (such as electric appliance retailers and building renovators) that will allow them to: i) discover each other, ii) educate themselves in order understand the difficulties and challenges that each one faces, and iii) finally interact and trade among. A serious game for energy efficiency, advanced research algorithms and data analytics as well as a novel competence-based education framework complement the SOCIALENERGY project's innovations.

Background— The relationship of atrioventricular nodal reentrant tachycardia to congenital heart disease (CHD) and the outcome of catheter ablation in this population have not been studied adequately. Methods and Results— A multicenter retrospective study was performed on patients with CHD who had atrioventricular nodal reentrant tachycardia and were treated with catheter ablation. There were 109 patients (61 women), aged 22.1±13.4 years. The majority, 86 of 109 (79%), had CHD resulting in right heart pressure or volume overload. Patients were divided into 2 groups: group A (n=51) with complex CHD and group B (n=58) with simple CHD. There were no significant differences between groups in patients’ growth parameters, use of 3-dimensional imaging, and type of ablation (radiofrequency versus cryoablation). Procedure times (251±117 versus 174±94 minutes; P =0.0006) and fluoroscopy times (median 20.8 versus 16.6 minutes; P =0.037) were longer in group A versus group B. There were significant differences between groups in the acute success of ablation (82% versus 97%; P =0.04), risk of atrioventricular block (14 versus 0%; P =0.004), and need for chronic pacing (10% versus 0%; P =0.008). There was no permanent atrioventricular block in patients who underwent cryoablation. After 3.2±2.7 years of follow-up, long-term success was 86% in group A and 100% in group B ( P =0.004). Conclusions— Atrioventricular nodal reentrant tachycardia can complicate the course of patients with CHD. This study demonstrates that the outcome of catheter ablation is favorable in patients with simple CHD. Patients with complex CHD have increased risk of procedural failure and atrioventricular block.

OBJECTIVES: Management strategy of patients with tetralogy of Fallot (TOF)—including timing, as well as surgical technique—remains a controversial topic. We sought to analyse both early and late results of our consistent policy of non-neonatal transatrial/transpulmonary (TA/TP) repair of TOF over almost 14 years, in order to assess preservation or possible deterioration of right ventricular (RV) function. METHODS: All 245 consecutive patients with TOF, referred to our group for repair between September 1997 and December 2010, have been prospectively followed up. Their clinical and echocardiographic data were retrospectively analysed. All underwent complete TA/TP repair at a median age of 1.6 years (range 0.2 to 55.6 years). RESULTS: Follow-up (median 8.5 years, range 0.5 to 14.6 years) was 100% completed. There was no operative death. There were three early re-operations: one for residual right ventricular outflow tract obstruction (RVOTO), one for intractable arrhythmias and one for remote second ventricular septal defect (VSD). There were three non-cardiac-related late deaths. Actuarial survival at 14 years was 98.8% (242/245). Twenty five patients required late re-operation, including 23 patients (9.4%, 23/245) who had pulmonary valve replacement (PVR). All other patients remained asymptomatic at follow-up. Mean residual right ventricular outflow tract (RVOT) pressure gradients have remained stable (6.8 ± 6.6 mmHg, 95% CI 5.9–7.6, early postoperatively, versus 7.6 ± 7.5 mmHg, 95% CI 6.6–8.6 at followup; P= 0.015). The mean qualitative grade of pulmonary valve insufficiency (PVI) increased (from 1.4 ± 0.9, 95% CI 1.3–1.5 at discharge to 2.1 ± 1.2, 95% CI 2–2.3 at follow-up; P < 0.001). Similarly, mean qualitative grade of tricuspid valve insufficiency (TVI) also increased (from 1 ± 0.7, 95% CI 0.9–1 at discharge to 1.5 ± 0.8, 95% CI 1.4–1.6 at follow-up; P < 0.001). However, RV function has remained normal in most patients. No significant arrhythmias have been noted. CONCLUSIONS: Our management strategy of non-neonatal TA/TP repair for all patients with TOF is associated with minimal early and late mortality and morbidity, relatively low re-operation rate, preserved RV function and excellent clinical outcomes at follow-up over almost 14 years. Since many patients demonstrated progressive increase in PVI and TVI, a much longer follow-up is necessary to determine the ultimate rates of late re-operation for pulmonary valve replacement (PVR).

Objectives To describe the experience with extracorporeal membrane oxygenation support for intractable primary arrhythmias in newborns and infants. Design Retrospective study. Setting A tertiary care pediatric hospital. Patients Patients younger than 1 yr supported with extracorporeal membrane oxygenation for primary cardiac arrhythmias were identified from the institutional extracorporeal membrane oxygenation registry. Interventions Extracorporeal membrane oxygenation support. Measurements and main results Clinical characteristics and outcomes were investigated for patients with primary cardiac arrhythmia supported with extracorporeal membrane oxygenation. Outcomes investigated were time from initiation of extracorporeal membrane oxygenation support to arrhythmia control, duration of extracorporeal membrane oxygenation support, and results of interventions performed while supported with extracorporeal membrane oxygenation. We summarized the independent categorical and continuous variables using frequencies, percentages, and medians and ranges, respectively. Extracorporeal membrane oxygenation support was used in nine patients for rescue therapy for primary tachyarrhythmia and bradycardia. The primary arrhythmias were: focal atrial tachycardia (n = 2); reentrant supraventricular tachycardia (n = 3); junctional ectopic tachycardia (n = 2); and congenital complete atrioventricular block (n = 2) patients. Seven patients presented with severe hemodynamic compromise, with six patients requiring extracorporeal cardiopulmonary resuscitation. All patients required extracorporeal membrane oxygenation within 24 hrs of initial presentation. Balloon atrial septostomy was performed in three patients and ablation was performed in two patients. Sinus rhythm was achieved in all reentrant supraventricular tachycardia and rate control was established in both patients with focal atrial tachycardia and in one patient with junctional ectopic tachycardia while using extracorporeal membrane oxygenation support. All patients survived to hospital discharge, and median follow-up for the cohort was 5 yrs. There was one late death; all survivors had good overall and neurologic outcomes. Conclusions The requirement of extracorporeal membrane oxygenation support in newborns and infants with intractable arrhythmia is rare. Extracorporeal membrane oxygenation support does potentially carry morbidity; however, to prevent arrhythmia-related mortality, extracorporeal membrane oxygenation support and/or extracorporeal cardiopulmonary resuscitation should be considered in the management of hemodynamically unstable primary arrhythmias as an emergent lifesaving procedure.

WOS: 000368445700024 PubMed ID: 25995398 We read with great interest the EP wire report entitled ‘How are arrhythmias managed in the paediatric population in Europe? Results of the European Heart Rhythm Survey’ by HernandezMadrid et al. 1 On behalf of the Arrhythmias and Electrophysiology Working Group of the Association for European Pediatric and Congenital Cardiology (AEPC), we would like to comment on the methodology and content of the article. The EHRA Research Network Centers do not include any of the dedicated paediatric centresproviding interventional electrophysiological therapy. This creates a major sampling errorand negatesthe validityof the conclusions of the survey. By including the paediatric centres, we would expect the results to be markedly different. The conclusion that paediatric catheter ablations in Europe are mainly performed by adult electrophysiology teams is not justified.

The objective of this study was to compare home blood pressure (HBP) vs. ambulatory (ABP) and clinic (CBP) measurements in terms of their association with target-organ damage in children and adolescents. A total of 81 children and adolescents (mean age 13 ± 3 years, 53 boys) referred for elevated CBP had measurements of CBP (1 visit), HBP (6 days) and ABP (24-h). Seventy-six participants were also assessed with carotid-femoral pulse wave velocity (PWV) and 54 with echocardiography. Average CBP was 122.1 ± 15.1/71 ± 12.9 mm Hg (systolic/diastolic), HBP 121.3 ± 11.5/69.4 ± 6.6 mm Hg and 24-h ABP 118.9 ± 12/66.6 ± 6.1 mm Hg. Left ventricular mass (LVM) was correlated with systolic blood pressure (BP) (coefficient r = 0.55/0.54/0.45 for 24-h/daytime/nighttime ABP, 0.53 for HBP and 0.41 for CBP; all P< 0.01). No significant correlations were found for diastolic BP. PWV was also significantly correlated with systolic BP (r = 0.52/0.50/0.48 for 24-h/daytime/nighttime ABP, 0.50 for HBP and 0.47 for CBP; all P < 0.01). Only diastolic ABP and HBP were significantly correlated with PWV (r = 0.30 and 0.28, respectively, P

Chronic right ventricular (RV) pacing is associated with deleterious effects on cardiac function. In an observational multicentre study in children with isolated atrioventricular (AV) block receiving chronic ventricular pacing, the importance of the ventricular pacing site on left ventricular (LV) function was investigated. Demographics, maternal autoantibody status and echocardiographic measurements on LV end-diastolic and end-systolic dimensions and volumes at age 1 year) for isolated AV block. LV fractional shortening (LVFS) and, if possible LV ejection fraction (LVEF) were calculated. Linear regression analyses were adjusted for patient characteristics. From 27 centres, 297 children were included, in whom pacing was applied at the RV epicardium (RVepi, n = 147), RV endocardium (RVendo, n = 113) or LV epicardium (LVepi, n = 37). LVFS was significantly affected by pacing site (p = 0.001), and not by maternal autoantibody status (p = 0.266). LVFS in LVepi (39 ± 5%) was significantly higher than in RVendo (33 ± 7%, p < 0.001) and RVepi (35 ± 8%, p = 0.001; no significant difference between RV-paced groups, p = 0.275). Subnormal LVFS (LVFS < 28%) was seen in 16/113 (14%) RVendo-paced and 21/147 (14%) RVepi-paced children, while LVFS was normal (LVFS ≥ 28%) in all LVepi-paced children (p = 0.049). These results are supported by the findings for LVEF (n = 122): LVEF was

Arterial stiffness, assessed by carotid-femoral pulse wave velocity (PWV) or indirectly by pulse pressure (PP) or ambulatory arterial stiffness index (AASI), is an independent predictor of cardiovascular disease in adults. However, in children limited evidence is available. This study investigated the usefulness of AASI and PP as indices of arterial stiffness in children and adolescents, by taking PWV as the reference method. Eighty-two children and adolescents (mean age 13.1±2.9 years) had 24-h ambulatory blood pressure (ABP) monitoring, PWV measurement and echocardiography. Compared with normotensives, subjects with hypertension (n=16) had higher 24-h ABP, 24-h PP and PWV, but not AASI. 24-h, PP was strongly correlated with age, weight, height, 24-h systolic ABP, PWV, left ventricular mass (LVM), LVM index, stroke volume and inversely with 24-h heart rate. AASI was also correlated with weight, height, systolic ABP and LVM, yet these associations were weaker than those of PP, and no significant correlations were found with PWV or LVM index. Moreover, closer agreement of PWV was observed with 24-h PP (71%, kappa 0.21) than with 24-h AASI (61%, kappa -0.06) in detecting subjects at the top quartile of the respective distributions. In children and adolescents, 24-h PP compared with AASI appears to be more closely associated with: (i) arterial stiffness assessed by PWV; (ii) target organ damage assessed by LVM index; and (iii) the presence of essential hypertension. These data suggest that the usefulness of AASI as an index of arterial stiffness in the pediatric population is questionable.

Background: Radiofrequency catheter ablation (RCA) of supraventricular tachycardia (SVT) in children is highly successful but requires exposure to radiation. Nonfluoroscopic mapping systems may significantly reduce fluoroscopy time. Methods: Forty consecutive pediatric patients who underwent RCA for accessory pathways (AP) or AV nodal reentrant tachycardia (AVNRT) with use of a nonfluoroscopic navigation system (Ensite® NavX™) (group A) were compared retrospectively to 40 consecutive patients with similar diagnoses who underwent RCA with fluoroscopic guidance only (group B). Results: Group A (mean age 12.1 ± 2.9 years, mean weight 47 ± 13.9 kg) consisted of 11 patients (27.7%) with AVNRT and 29 (72.5%) with AP. Group B (mean age 10.9 ± 3.1 years, mean weight 47.1 ± 17.1 kg) consisted of 7 patients (17.5%) with AVNRT and 33 (82.5%) with AP. There were no significant differences in AP location, patients with congenital heart disease, and number of radiofrequency lesions. Fluoroscopy time was significantly shorter in group A than in group B (10.4 ± 6.1, range 3.1–28.8 minutes, vs 24.9 ± 16.0, range 4.4–82.0 minutes, P < 0.0001). Procedure duration was also significantly shorter in group A than in group B (170 ± 68.5, range 90–420 minutes, vs 218 ± 69.3, range 90–360 minutes, P < 0.0001). Initial success was 95% in group A and 100% in group B. Tachycardia recurrences occurred in two patients in group A (5%) and six patients in group B (15%). Final success, including repeat ablations for recurrences or failures, was 100% in both groups. Conclusions: The use of a nonfluoroscopic system for catheter navigation significantly reduced fluoroscopy exposure and total procedure duration of RCA of common SVT substrates in children.

Apart from closure of atrial septal defects, there is little information concerning the use of the CardioSEAL family of occluders in congenitally malformed hearts. We review here our initial experience using the CardioSEAL and STARFlex occluders in 12 patients aged 17.3 ± 11.2 years, with a range from 4 to 34 years. Of the patients, 5 had fenestrated extracardiac Fontan procedures, 5 had persistent patency of the arterial duct, 1 had a leak across a Mustard baffle, and the final patient had a huge pulmonary arteriovenous malformation. We implanted successfully 9 CardioSEAL, and 3 STARFlex occluders, with sizes from 17 to 40 mm. In one patient, the occluder embolized to the right pulmonary artery, from where it was retrieved through the catheter. In two patients, there was a trivial residual leak immediately after implantation, but no patient had a residual leak after 6 months of follow-up. We noted improved ventricular dimensions, without any fractures of the arms of the occluders, perforations, or disturbances of flow after 2.4 ± 0.9 years of follow-up. We have demonstrated, therefore, the versatility of the CardioSEAL and STARFlex occluders, which have been used safely and effectively to close a variety of intra and extracardiac communications other than atrial septal defects.

Aims: Transcatheter implantation of valved stents (Melody and Edwards valves) for replacement of the pulmonary valve is currently an established procedure. We reviewed our experience on implantation of such valves in the tricuspid valve position. Methods and results: Transcatheter valve implantation in the tricuspid position was attempted in five patients. Four patients had predominantly tricuspid valve regurgitation, two of whom also had tricuspid valve stenosis. All patients had severely symptomatic right heart failure. Patient median age and weight were 12 years and 50 kg (range six-43 years and 13-68 kg, respectively). All patients had a bioprosthetic valve already in place. The mean gradient across the tricuspid valve decreased from 12 to 3 mmHg after the procedure. Median procedure time and fluoroscopy time were 100 and 39 min (range 60-180 and 30-57 min, respectively). The patients’ functional class improved from NYHA Class III to II in three and from Class III to I in two patients during a follow-up period of 15-22 months. Conclusions: Transcatheter replacement of malfunctioning bioprosthetic valves in the tricuspid position using valved stents is an attractive alternative to repeat surgery in high-risk or multi-operated patients. Longer follow-up and a larger number of patients are required to establish the long-term benefit of the procedure and freedom from reinterventions.

Permanent junctional reciprocating tachycardia (PJRT) is an uncommon form of supraventricular tachycardia in children. Treatment of this arrhythmia has been considered difficult because of a high medication failure rate and risk of cardiomyopathy. Outcomes in the current era of interventional treatment with catheter ablation have not been published.To describe the presentation and clinical course of PJRT in children.This is a retrospective review of 194 pediatric patients with PJRT managed at 11 institutions between January 2000 and December 2010.The median age at diagnosis was 3.2 months, including 110 infants (57%; aged1 year). PJRT was incessant in 47%. The ratio of RP interval to cycle length was higher with incessant than with nonincessant tachycardia. Tachycardia-induced cardiomyopathy was observed in 18%. Antiarrhythmic medications were used for initial management in 76%, while catheter ablation was used initially in only 10%. Medications achieved complete resolution in 23% with clinical benefit in an additional 47%. Overall, 140 patients underwent 175 catheter ablation procedures with a success rate of 90%. There were complications in 9% with no major complications reported. Patients were followed for a median of 45.1 months. Regardless of treatment modality, normal sinus rhythm was present in 90% at last follow-up. Spontaneous resolution occurred in 12% of the patients.PJRT in children is frequently incessant at the time of diagnosis and may be associated with tachycardia-induced cardiomyopathy. Antiarrhythmic medications result in complete control in few patients. Catheter ablation is effective, and serious complications are rare.

Background Congenital left ventricular aneurysm is a poorly understood and potentially lethal entity. Methods and Results In a clinicopathologic study of 7 new cases, the major presenting features in 6 patients were congestive heart failure in 4, ventricular arrhythmias in a 32-week fetus, and multiple congenital anomalies in a fetus with trisomy 13. Accurate diagnosis was achieved in all 3 living patients by echocardiography, angiocardiography, and magnetic resonance imaging. The aneurysm was predominantly apical in 3 and involved most of the left ventricular free wall in 4. Of the 3 living patients, medical management alone sufficed in 2. The third, a newborn boy, underwent a new and successful aneurysm-exclusion left ventriculoplasty. The mitral valve was abnormal in all 4 autopsied cases, the papillary muscles being short, thin, or absent. The aneurysm was thinner and its area was larger than that of the nonaneurysmal left ventricle in all necropsied patients. Conclusions Congenital left ventricular aneurysm appears to be a developmental anomaly, an idiopathic dysplasia of left ventricular endocardium and myocardium. No evidence of a viral etiology was found. Some neonates can be managed medically, but others require urgent surgical intervention. A new surgical operation is presented, a functional left ventricular aneurysmectomy that minimizes intraoperative and postoperative blood loss and that preserves the coronary arteries. (Am Heart J 2001;141:491-9.)

We report a case of congenital atresia of the superior vena cava (SVC) with stenotic anastomoses between systemic and pulmonary veins, resulting in cyanosis and symptoms consistent with SVC syndrome in an infant.

OBJECTIVES The purpose of this study was to determine the efficacy and risks of radiofrequency ablation of various forms of supraventricular tachycardia after Mustard and Senning operations for d-transposition of the great arteries. BACKGROUND In this patient group, the reported success rate of catheter ablation of intraatrial reentry tachycardia is about 70% with a negligible complication rate. There are no reports of the use of radiofrequency ablation to treat other types of supraventricular tachycardia. METHODS Standard diagnostic criteria were used to determine supraventricular tachycardia type. Appropriate sites for attempted ablation included 1) intraatrial reentry tachycardia: presence of concealed entrainment with a postpacing interval similar to tachycardia cycle length; 2) focal atrial tachycardia: a P-A interval ≤−20 ms; and 3) typical variety of atrioventricular (AV) node reentry tachycardia: combined electrographic and radiographic features. RESULTS Nine Mustard and two Senning patients underwent 13 studies to successfully ablate all supraventricular tachycardia substrates in eight (73%) patients. Eight of eleven (73%) patients having intraatrial reentry tachycardia, 3/3 having typical AV node reentry tachycardia, and 2/2 having focal atrial reentry tachycardia were successfully ablated. Among five patients having intraatrial reentry tachycardia (IART) and not having ventriculoatrial (V-A) conduction, two suffered high-grade AV block when ablation of the systemic venous portion of the medial tricuspid valve/inferior vena cava isthmus was attempted. CONCLUSIONS Radiofrequency catheter ablation can be effectively and safely performed for certain supraventricular tachycardia types in addition to intraatrial reentry. A novel catheter course is required for slow pathway modification. High-grade AV block is a potential risk of lesions placed in the systemic venous medial isthmus.

Junctional ectopic tachycardia is usually a limited but potentially life-threatening postoperative arrhythmia. We describe a case of malignant postoperative junctional ectopic tachycardia in a 13-month-old child who had undergone transatrial and transpulmonary repair of tetralogy of Fallot resistant to all conventional therapeutic measures and complicated by recurrent ventricular tachycardia. The arrhythmia was finally treated by open surgical cryoablation of the atrioventricular node and the implantation of a permanent pacemaker. The patient made an uneventful recovery followed by good long-term outcome.

We have read with interest the article by Hoffmayer et al,1 titled Variable Clinical Features and Ablation of Manifest Nodofascicular/Ventricular Pathways. We agree with the authors’ conclusions that nodofascicular/ventricular (NFV) pathways can participate in tachycardia either as bystanders, as for example with atrioventricular node reentry tachycardia (AVNRT), which is a commonly associated arrhythmia, or as an integral part of the reentry circuit. We have previously published a case report of an 11-year-old patient with these characteristics in whom cryoablation in the right midseptal area eliminated both the slow atrioventricular nodal pathway and the NFV pathway, thus proving a close anatomic relationship between the 2.2 We have several comments to make on the 4 cases presented in this article. 1. Case 1: Among the 4, this case best documents the presence of a NFV pathway. There is evidence of antegrade conduction with decremental properties (Figure 2A); inducibility of tachycardia with the same morphology as with the pre-excited atrial extrasystoles; ventriculo-atrial decremental conduction; and continuation of the tachycardia despite ventriculo-atrial block (Figure 2C). Our interpretation of Figure 2D is as follows: the initial 3 beats of narrow complex tachycardia represent typical AVNRT with retrograde concealed conduction in the NFV pathway, thus preventing antegrade conduction. In the fourth beat, block in the distal atrioventricular node (or in structures downstream of it) develops, allowing antegrade conduction down the NFV pathway and resulting in antidromic tachycardia. The change from simultaneous retrograde conduction from atrioventricular …

A patient with repaired tetralogy of Fallot presented with recurrent syncope and had multiple haemodynamically unstable ventricular tachycardias unresponsive to antiarrhythmic medications.Ventricular tachycardias became haemodynamically tolerated with amiodarone, procainamide and dopamine, permitting activation and entrainment mapping. Radiofrequency ablation of three tachycardia circuits was performed. Ventricular tachycardia could not be induced 1 week, and 3 and 9 months later.Radiofrequency ablation is feasible for multiple, haemodynamically unstable ventricular tachycardias in repaired tettralogy of Fallot

Repair of scimitar syndrome presenting in infancy involves either tunneling or reimplantation of the anomalous vein to the left atrium and may be fraught with serious complications such as thrombosis and secondary pulmonary infarction necessitating pneumonectomy. The authors present the case of a severely symptomatic infant with scimitar syndrome, managed initially with closure of an atrial septal defect in the hope of avoiding a repair with considerable risk of scimitar vein thrombosis and pulmonary infarction. Despite initial clinical improvement, subsequent rapid development of spontaneous massive emphysematous degeneration of the right lung necessitated emergency pneumonectomy, which was accomplished via the median sternotomy approach.

Cryoablation is increasingly used for the treatment of atrioventricular nodal reentrant tachycardia (AVNRT). There are limited data regarding its efficacy and late outcomes in the pediatric population.We reviewed the clinical records of 70 consecutive pediatric and adolescent patients (mean age: 12.2 ± 3, range: 5-19 years) with AVNRT, with or without additional structural heart disease, who underwent catheter ablation with the intention to use cryoablation as the primary modality between September 2004 and July 2011.The acute success rate was 97.14%. No long-term complications occurred. Patients were followed up for an average time of 46 ± 22.5 months (range 5-90). The recurrence rate was 16%, decreasing from 28% in the first 25 cases to 8.9% in the last 45 cases (p0.05). Wenckebach point prolongation during cryoapplications was associated with a lower recurrence rate (p0.05). No other risk factors for recurrence were identified, including persistence of slow pathway conduction. Patients with congenital heart disease had a similar success rate to patients with a structurally normal heart.When applied to pediatric patients, cryoablation has an excellent success and safety profile, which can improve with increasing experience. Transient Wenckebach point prolongation during cryo-applications may be associated with improved late outcomes.

Background— We evaluated the effects of the site of ventricular pacing on left ventricular (LV) synchrony and function in children requiring permanent pacing. Methods and Results— One hundred seventy-eight children (aged R =0.80, P =0.031). Pacing from the RV outflow tract/lateral RV predicted significantly decreased LV function (LV ejection fraction P =0.005), whereas LV apex/LV midlateral wall pacing was associated with preserved LV function (LV ejection fraction ≥55%; odds ratio, 8.26; confidence interval, 1.46–47.62; P =0.018). Presence of maternal autoantibodies, gender, age at implantation, duration of pacing, DDD mode, and QRS duration had no significant impact on LV ejection fraction. Conclusions— The site of ventricular pacing has a major impact on LV mechanical synchrony, efficiency, and pump function in children who require lifelong pacing. Of the sites studied, LV apex/LV midlateral wall pacing has the greatest potential to prevent pacing-induced reduction of cardiac pump function.

Background— Life-threatening disorders of heart rhythm may arise during infancy and can result in the sudden and tragic death of a child. We performed exome sequencing on 2 unrelated infants presenting with recurrent cardiac arrest to discover a genetic cause. Methods and Results— We ascertained 2 unrelated infants (probands) with recurrent cardiac arrest and dramatically prolonged QTc interval who were both born to healthy parents. The 2 parent-child trios were investigated with the use of exome sequencing to search for de novo genetic variants. We then performed follow-up candidate gene screening on an independent cohort of 82 subjects with congenital long-QT syndrome without an identified genetic cause. Biochemical studies were performed to determine the functional consequences of mutations discovered in 2 genes encoding calmodulin. We discovered 3 heterozygous de novo mutations in either CALM1 or CALM2 , 2 of the 3 human genes encoding calmodulin, in the 2 probands and in 2 additional subjects with recurrent cardiac arrest. All mutation carriers were infants who exhibited life-threatening ventricular arrhythmias combined variably with epilepsy and delayed neurodevelopment. Mutations altered residues in or adjacent to critical calcium binding loops in the calmodulin carboxyl-terminal domain. Recombinant mutant calmodulins exhibited several-fold reductions in calcium binding affinity. Conclusions— Human calmodulin mutations disrupt calcium ion binding to the protein and are associated with a life-threatening condition in early infancy. Defects in calmodulin function will disrupt important calcium signaling events in heart, affecting membrane ion channels, a plausible molecular mechanism for potentially deadly disturbances in heart rhythm during infancy.

BACKGROUND Despite the current clinical use of radiofrequency (RF) catheter ablation in infants, the acute and late effects of RF lesion production in immature myocardium remain unknown. This study was specifically designed to investigate the pathology of RF lesions in developing sheep myocardium. METHODS AND RESULTS In study 1, RF lesions were made on the epicardial left ventricular surface of the beating heart in 15 sheep, 5 approximately 4 weeks of age (11.0 +/- 1.0 kg) and 10 approximately 8 weeks of age (23.8 +/- 3.4 kg), to assess the effects of RF application duration (10 to 90 seconds) and electrode tip temperature (45 degrees to 90 degrees C) on lesion size in immature myocardium. Lesion width and depth increased asymptotically with RF duration, to 7.0 +/- 0.7 and 4.8 +/- 1.0 mm at 90 seconds, respectively. The time to reach one-half lesion size was 6.5 seconds for width and 12.0 seconds for depth. Lesion width increased nearly linearly with tip temperature above 50 degrees C, but depth followed a sigmoid relation, with no increase above 80 degrees C. In study 2, RF lesions were made in all four cardiac chambers under fluoroscopic guidance in 19 infant sheep (10.9 +/- 1.4 kg). Lesion sizes and histological characteristics were assessed acutely (acute, n = 5), at 1.07 +/- 0.02 months (1 month, n = 5), and at 8.5 +/- 0.5 months (late, n = 9). Atrial and ventricular lesions but not atrioventricular groove lesions apparently increased in size during the follow-up period. Atrial lesions width increased from 5.3 +/- 0.5 to 8.7 +/- 0.7 mm at 1 month (164%) but did not increase further at late follow-up, while ventricular lesion width increased from 5.9 +/- 0.8 to 10.1 +/- 0.7 mm (171%) at late follow-up but was not significantly changed at 1 month. Histological evaluation revealed replacement of normal myocytes with fibrous and elastic tissue at 1 month and late follow-up in all locations but also demonstrated a poorly delineated border with multiple extensions of fibrous and elastic tissue into surrounding normal myocardium in late ventricular lesions. CONCLUSIONS RF lesion formation in immature sheep myocardium is similar to that in adult myocardium acutely but is associated with late lesion enlargement and fibrous tissue invasion of normal myocardium. These findings may have implications for clinical RF ablation procedures in infants.

We sought to assess the impact of routine use of a nonfluoroscopic navigation system in the procedural aspects of radiofrequency ablation of accessory pathways (APs) in pediatric and congenital heart disease (CHD) patients and the reduction of fluoroscopy in different pathway locations.This was a retrospective review of 192 patients, divided in two groups: group A (76 patients, fluoroscopic only ablation) and group B (116 patients, combined use of fluoroscopy and a nonfluoroscopic system (NavX™). Comparison of procedural aspects (procedure time, fluoroscopy time, success, complications, and recurrences) was performed.The two groups were comparable in terms of age, AP location, and presence of CHD. The mean age was 11.34 ± 4.65 years in group A versus 10.91 ± 3.68 years in group B. The procedure duration was significantly shorter in group B than in group A (177.06 ± 62.18 vs 242.45 ± 99.07) (P0.001). There was a significant reduction in the fluoroscopy time in group B compared to group A (8.27 ± 8.23 vs 39.77 ± 32.65 minutes) (P0.001). The difference between the two groups was statistically significant in all categories of APs. The success rate was 97.4% in group A and 96.6% in group B. There were no complications directly related to the use of the nonfluoroscopic system. There was no difference in the recurrence rate.The use of a nonfluoroscopic system for catheter navigation resulted in significant reduction of total procedure and fluoroscopy time during catheter ablation of APs in pediatric and CHD patients, regardless of the location of the pathway, without a compromise in safety and efficacy.

Introduction The combination of anomalous left coronary artery origin from the pulmonary artery and an accessory pathway has not been reported previously in the medical literature. In medicine, the coexistence of two clinical causes can lead to the same clinical findings, and this can make the researcher's attempt to distinguish between the two of them and, hence, the correct diagnosis and treatment difficult. Case presentation A six-month-old boy from Pakistan was brought to our hospital with tachypnea and supraventricular tachycardia and, on the basis of echocardiography and multi-slice computed tomography, was diagnosed with an anomalous left coronary artery origin from the pulmonary artery. The presence of an anomalous left coronary artery origin from the pulmonary artery was not initially recognized, and left ventricular dysfunction was considered as a result of supraventricular tachycardia. He underwent direct re-implantation of the left coronary artery to the aorta using the trapdoor flap technique. Recurrent episodes of supraventricular tachycardia resistant to maximal pharmacological treatment occurred post-operatively. A left posterolateral accessory pathway was successfully ablated by using a trans-septal approach. Conclusions It should not be forgotten by anyone that many times in medicine what seems obvious is not correct. It can be difficult to distinguish two clinical entities, and frequently one is considered a result of the other. This is the first report of the coexistence of an anomalous left coronary artery origin from the pulmonary artery and recurrent supraventricular tachycardia due to an accessory pathway in a child that was treated successfully with combined surgical and interventional electrophysiological treatment. This case may represent a first educational step in the field of congenital heart disease, that is, that anomalies such as an anomalous left coronary artery origin from the pulmonary artery may be concealed in a child with other serious cardiac problems, in this case mitral regurgitation, dilation of the left ventricle, and recurrent episodes of tachycardia.

Large pulmonary arteriovenous malformations (PAVMs) carry a significant risk of neurologic complications and present technical difficulties in transcatheter treatment with use of coils or detachable balloons. A 26-year-old man with a giant PAVM, who had undergone unsuccessful attempted closure with use of a Gianturco-Grifka occlusion device in the past, underwent successful transcatheter embolization with two Cardioseal double umbrella devices designed for occlusion of intracardiac communications. The procedure was technically easy, had no complications, and provided sustained improvement in arterial saturation and exercise tolerance during follow-up. Transcatheter double umbrella device occlusion of large arteriovenous malformations is feasible and should be considered, especially for very large fistulas.

We report a case of congenital atresia of the superior vena cava (SVC) with stenotic anastomoses between systemic and pulmonary veins, resulting in cyanosis and symptoms consistent with SVC syndrome in an infant.