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This article discusses the risk of ventricular tachycardias (VT) in patients who have undergone repaired Tetralogy of Fallot (rTOF) surgery. The study included 39 patients who underwent electrophysiological study for VT risk stratification. The researchers found that slow conducting anatomic isthmuses (SCAI) were present in the majority of patients, with the most common SCAI being isthmus 3 and isthmus 4. Ablation procedures were successful in 87% of patients, with only one patient experiencing recurrence of VT/VF. The study suggests that implantable cardioverter-defibrillator (ICD) implantation may be necessary in some cases. [Extracted from the article]

Aims: Coherent mapping (CM) uses a new algorithm to identify critical conduction isthmuses of atrial tachycardias (ATs). We analysed our experience of ablation of AT in patients with congenital heart disease (CHD) with this new technology., Methods and Results: All patients with CHD who had CM of AT using the high-density mapping PENTARAY™ catheter and three-dimensional electroanatomic mapping system Carto3 between June 2019 and June 2021 were included retrospectively (n = 27). As a control group, 27 patients with CHD and mapping of AT without CM between March 2016 and June 2019 were included. In total, 54 ablation procedures were performed in 42 patients [median age 35 (interquartile range, IQR 30-48) years] and 64 ATs were induced and mapped (thereof 50 AT intraatrial re-entrant tachycardia and 14 AT ectopic AT). The median procedure duration was 180 (120-214) min and median fluoroscopy time was 10 (5.2-14) min. Acute success was 100% (27/27) in the Coherence group and 74% (20/27) in the non-Coherence group (P = 0.01). During follow-up [median 26 (12-45) months], AT recurred in 28/54 patients, thereof 15 patients needed a re-ablation procedure. Log-rank test showed no difference in recurrence rate between the two groups (P = 0.29). Three minor complications occurred (5.5%)., Conclusion: Mapping of AT in patients with CHD using the PENTARAY™ mapping catheter and the CM algorithm led to excellent acute success. All ATs were possible to map and no complications related to the PENTARAY™ mapping catheter were observed. Thus, the use of the CM algorithm represents a promising tool in patients with CHD and complex AT., Competing Interests: Conflict of interest: None declared., (© The Author(s) 2023. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Introduction: Atrial tachycardias (AT) in patients with congenital heart disease (CHD) are significantly contributing to morbidity and mortality. Aim of this study was to evaluate the long-term course of CHD patients requiring repeat ablation procedures (RAP) of AT., Patients and Methods: All 144 patients with CHD who had undergone ablation of AT at our center between January 2003 and October 2018 were enrolled. Patients were classified according to the complexity of CHD: complex CHD (cCHD), moderate CHD (mCHD), and simple CHD (sCHD)., Results: A total of 101 RAP were performed in 64 patients. One RAP was performed in n = 40, two in n = 13, three in n = 10, and five in n = 1. Acute success rate was 82% (83/101) and was not associated with the complexity of CHD (p = 1.0). Number of procedures was lower in patients with sCHD than in patients with mCHD and cCHD (sCHD 1.3 ± 0.6, mCHD 1.8 ± 1.0, and cCHD 1.8 ± 1.1, p = .04). RAP were most frequent in patients after Fontan palliation or Atrial switch procedure (2.0 ± 1.1 [n = 41] vs. 1.6 ± 0.9 all others, p = .016) and in patients with multiple unstable AT's (2.5 ± 1.1 [n = 11] vs. 1.7 ± 1.0, p = .008). Major complications occurred in 4/101 procedures. Complete follow-up was available in 125 patients. Since last RAP 73% of the patients were in sinus/atrial rhythm and 34/125 patients (27%) with AT recurrence did not require re-ablation with mean follow-up of 52 ± 40 months., Conclusions: Recurrences after ablation of AT in CHD patients were frequent. After RAP promising long-term results could be achieved. Data encourage repetitive ablation procedures in this patient population., (© 2022 The Authors. Journal of Cardiovascular Electrophysiology published by Wiley Periodicals LLC.)

Objectives: The purpose of this study was to evaluate long-term safety and efficacy of catheter ablation of accessory atrioventricular pathways (AP) in a pediatric cohort., Background: Radiofrequency catheter ablation of accessory AP is the recommended treatment for patients with atrioventricular re-entrant tachycardia. Data on long-term results ≥1 year after AP ablation in pediatric patients is sparse., Methods: A total of 296 patients <18 years of age who had undergone radiofrequency-AP ablation between October 2002 and June 2015 were included into the study. Follow-up was >1 year in all patients. Median age at ablation had been 11.6 years, and median follow-up was 5.6 years. Recurrence of AP conduction after ablation was defined as documentation of pre-excitation, supraventricular tachycardia attributable to AP, or proof of AP conduction during repeat electrophysiological study., Results: AP ablation succeeded in 268 of 296 individuals (91%). After successful ablation, recurrence of AP conduction was observed in 29 of 268 individuals (10.8%). Of those 29, 23 (79%) had AP recurrence within the first year after ablation, whereas 13 (45%) had recurrence of AP conduction already within the first month. Six patients had late recurrence of AP conduction >1 year post-ablation. Procedural success and freedom from AP conduction after a single ablation procedure was 86% at 1 month, 83% at 1 year, and 81% at 5 years after ablation., Conclusions: After radiofrequency ablation of AP in children, recurrence of AP conduction occurred in 23 subjects (8% of the study cohort) within the first year after ablation. Late recurrences >1 year after ablation were noticed in 6 children (2% of the study group), highlighting the need for longer follow-up >1 year. Results of the present study on late AP recurrence should be taken into account whenever families are counselled for pediatric AP ablation., (Copyright © 2018 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Radiofrequency catheter ablation has become the treatment strategy of choice for atrial tachyarrhythmias in patients with congenital heart disease (CHD). We analyzed results of radiofrequency catheter ablation in a large cohort of patients with CHD with special reference to complexity of underlying anatomy., Methods and Results: One hundred and forty-four patients with CHD and atrial tachyarrhythmias undergoing radiofrequency catheter ablation were classified according to complexity of underlying CHD: simple CHD, n=18 (12%); moderate CHD, n=53 (37%); and complex CHD, n=73 (51%). Overall acute success was achieved in 81% of the patients. Acute success was lower for tachycardias involving the left atrium compared with right atrial tachycardias. Complexity of CHD was associated with longer procedure duration. Tachycardia recurrence was observed in 54% of the patients after a total follow-up of 7.4 years. 75% of all recurrences occurred within the first year. Recurrence of tachycardia was more likely in patients with complex surgical atrial anatomy (ie, Fontan palliation or atrial switch procedure). Major complications occurred in 4 patients and were related to vascular access., Conclusions: Acute procedural success of atrial tachycardia ablation in congenital heart patients was not influenced by complexity of CHD. Long-term outcome with regard to tachycardia recurrence was worse in patients with complex surgical atrial anatomy., (© 2017 American Heart Association, Inc.)

To improve long-term outcome after cryoablation of substrates of supraventricular tachycardia, application of two and three consecutive freeze-thaw cycles has been performed. The effect of triple freeze-thaw cycles on lesion formation within developing myocardium and coronary arteries, however, has not been studied yet. In eight piglets (mean age 15 weeks, weight 15-20 kg), 30 cryolesions (three consecutive freeze-thaw cycles) were applied to the atrial aspect of both AV valve annuli (n = 18) as well as to ventricular myocardium below the valves (n = 12). Coronary angiography was performed before and after cryoenergy application. The animals were reevaluated by coronary angiography and intracoronary ultrasound (ICUS) after 48 h. All hearts were removed for histological examination of the lesions subsequently. After staining (hematoxylin-eosin, desmin immunohistochemistry), lesions was measured by planimetry with a digital virtual miscroscope analysis system and volumes of the cryolesions were calculated. Mean atrial lesion volume was 190.68 ± 167.53 mm 3 (n = 18), and mean ventricular lesion volume was 184.34 ± 107.42 mm 3 (n = 12). Compared with previously reported data on lesion volumes after single and double freeze-thaw cycles, lesions were significantly larger. Coronary arteries were unaffected on coronary angiography as well as on ICUS. No affection of coronary arteries was found on histological examination. Application of three consecutive freeze-thaw cycles resulted in increased lesion volume compared with single and double freeze-thaw cycles. No affection of the coronary arteries was evident. To evaluate the clinical benefit and safety of triple cryoenergy application for catheter ablation, prospective randomized trials are required.

Background: Catheter ablation of the slow conducting pathway (SP) is treatment of choice for atrioventricular nodal reentrant tachycardia (AVNRT). Although there are abundant data on AVNRT ablation in adult patients, little is known about the long-term results ≥3 years after AVNRT ablation in pediatric patients., Methods and Results: Follow-up data from 241 patients aged ≤18 years who had undergone successful AVNRT ablation were analyzed. Median age at ablation had been 12.5 years, and median follow-up was 5.9 years. Radiofrequency current had been used in 168 patients (70%), whereas cryoenergy had been used in 73 patients (30%). Procedural end point of AVNRT ablation had been either SP ablation (no residual dual atrioventricular nodal physiology) or SP modulation (residual SP conduction allowing for a maximum of one atrial echo beat). After the initial AVNRT ablation, calculated freedom from AVNRT was 96% at 1 year, 94% at 3 years, 93% at 5 years, and 89% at 8 years. Age, sex, body weight, the choice of ablation energy, and the procedural end point of AVNRT ablation did not impact freedom from AVNRT. Six of 22 AVNRT recurrences (27%) occurred ≥5 years after ablation. No late complications including atrioventricular block were noted., Conclusions: Cumulatively, catheter ablation of AVNRT continued to be effective in >90% of our pediatric patients during the long-term course. A significant part of recurrences occurred >5 years post ablation. Body weight, energy source, and the end point of ablation had no impact on long-term results. No adverse sequelae were noted., (© 2016 American Heart Association, Inc.)

Background: Monitoring of catheter contact force during catheter ablation of atrial fibrillation has been shown to increase efficacy and safety. However, almost no data exists on the use of this technology in catheter ablation of intraatrial reentrant tachycardia in patients with congenital heart disease. The aim of the present study was to evaluate the impact of contact force monitoring during catheter ablation of intraatrial reentrant tachycardia in those patients., Methods: Catheter ablation of intraatrial reentrant tachycardia using monitoring of catheter contact force was performed in 28 patients with congenital heart disease (CHD). Thirty-two patients matched according to gender, age, and body weight with congenital heart disease undergoing catheter ablation without contact force monitoring served as control group. Parameters reflecting acute procedural success, long-term efficacy, and safety were compared., Results: Acute procedural success was statistically not different in both groups (contact force 93 % vs. control 84 %, p = 0.3). Likewise the recurrence rate 1 year after ablation as shown by Kaplan-Meier analysis did not differ (contact force 28 % vs. control 37 %, p = 0.63). Major complications were restricted to groin vessel injuries and occurred in 3 out of 60 patients (contact force n = 1; control n = 2). Complications related to excessive catheter contact force were not observed., Conclusion: The present study did not show superiority of catheter contact force monitoring during ablation of intraatrial reentrant tachycardia in patients with CHD in terms of efficacy and safety. Higher contact force compared to pulmonary vein isolation might therefore be required to increase the efficacy of catheter ablation of intraatrial reentrant tachycardia in patients with congenital heart disease.

Aims: Catheter ablation of atrial re-entrant tachycardia in patients after atrial switch procedure for transposition of the great arteries or with a Fontan circulation is technically challenging if the critical part of the re-entry circuit is located within the pulmonary venous atrium (PVA). We report our experience in transbaffle access (TBA) to the PVA for ablation of atrial re-entrant tachycardia focusing on technical details., Methods and Results: In eight patients, six after Mustard procedure and two with a Fontan circulation, endocardial mapping of atrial re-entrant tachycardia revealed the critical part of the re-entry circuit within the PVA. A total of 10 ablation procedures were performed. Detailed angiographic assessment of the anatomy of the systemic and pulmonary venous atria was performed prior to baffle puncture. Transbaffle access was successfully established with a standard transseptal needle in 9 of 10 procedures. No major complications occurred. At the end of the procedure and the removal of the transseptal sheath, there was no residual shunt in any patient., Conclusion: Transbaffle access to the PVA for ablation of atrial re-entrant tachycardia is feasible, less invasive than alternative approaches and can be safely applied in patients after Mustard procedure or with a Fontan circulation. However, the rigidity of prosthetic material may preclude baffle puncture at least in a subset of those patients., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.)

Accessory atrioventricular pathways (AP) are the most common substrate for paroxysmal supraventricular tachycardia in infants and small children. Up-to-date data on AP ablation in infants and small children are limited. The aim of the present study was to gain additional insight into radiofrequency (RF) catheter ablation of AP in infants and toddlers focusing on efficacy and safety in patients with a body weight of ≤ 15 kg. Since 10/2002, RF ablation of AP was performed in 281 children in our institution. Indications, procedural data as well as success and complication rates in children with a body weight ≤ 15 kg (n = 22) were compared with children > 15 kg (n = 259). Prevalence of structural heart anomalies was significantly higher among children ≤ 15 kg (27 vs. 5.7 %; p = 0.001). Procedure duration (median 262 vs. 177 min; p = 0.001) and fluoroscopy time (median 20.6 vs. 14.0 min; p = 0.007) were significantly longer among patients ≤ 15 kg. Procedural success rate did not differ significantly between the two groups (82 vs. 90 %). More RF lesions were required for AP ablation in the smaller patients (median 12 vs. 7; p = 0.019). Major complication rate was significantly higher in children ≤ 15 kg (9 vs. 1.1 %; p = 0.05) with femoral vessel occlusion being the only major adverse event in patients ≤ 15 kg. Catheter ablation of AP in children was effective irrespective of body weight. In children ≤ 15 kg, however, procedures were more challenging and time-consuming. Complication rate and number of RF lesions in smaller children were higher when compared to older children.

Background: Treatment of congenital junctional ectopic tachycardia (JET) is often challenging. In the majority of patients affected, a combination of ≥2 antiarrhythmic drugs is required for JET control., Objective: The purpose of this study was to assess the efficacy and safety of adjunctive ivabradine therapy for pediatric congenital JET., Methods: Since January 2015, 5 consecutive patients aged 10 days to 3.5 years (median 8 weeks) were treated with adjunctive ivabradine for congenital JET. All patients had previously undergone antiarrhythmic therapy with unsatisfactory control of JET. Ivabradine was administered orally at an initial dosage of 0.05-0.1 mg/kg/d divided into 2 single doses and was increased up to 0.28 mg/kg/d if necessary., Results: In all 5 patients, ivabradine proved to be successful in controlling JET. Complete suppression of JET and conversion into sinus rhythm were achieved in 4 of 5 patients. The remaining patient had effective heart rate control with persistent slow JET. Mean heart rate was reduced by 31% compared to pre-ivabradine (P = .03) as assessed by 24-hour Holter monitoring. Echocardiography revealed improvement of left ventricular function in all 3 patients with previously impaired left ventricular function. No significant side effects of ivabradine were encountered during median follow-up of 135 days (range 37-203 days)., Conclusion: In our group of patients with congenital JET, adjunctive treatment with ivabradine resulted in effective and safe rhythm/heart rate control and therefore may be recommended early in the course of this rare inborn tachyarrhythmia., (Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: AV nodal reentrant tachycardia (AVNRT) is commonly encountered in pediatric patients. Definite treatment can be achieved by catheter ablation. The purpose of the study was to evaluate the efficacy and safety of AVNRT ablation focusing on children with a body weight ≤25 kg., Patients and Results: Catheter ablation of AVNRT was attempted in 253 patients. Median age was 12.5 years; median body weight was 48.7 kg. 25 (9.9 %) children had a body weight ≤25 kg. Congenital heart disease was present in 6 patients (2.4 %). Procedural success was achieved in 98 % using radiofrequency, in 100 % using cryoenergy alone, and in 94 % using both energy sources. In patients with a body weight ≤25 kg, success was achieved in 96 %. In patients ≤25 kg, fluoroscopy and procedure duration did not differ from those >25 kg. The rate of major complications was significantly higher in the patients ≤25 kg (12 vs. 2.2 %, p = 0.04). Permanent AV block after RF ablation occurred in 2 patients with congenital heart disease and one infant with a body weight of 8.7 kg., Conclusions: Catheter ablation of AVNRT in children and adolescents was safe and effective. Infants and small children with a body weight ≤25 kg had a higher prevalence of serious complications. This should alert physicians in decision making toward catheter ablation in these patients. In patients with congenital heart disease and different anatomy of the cardiac conduction system, operators must be aware of an increased risk for AV block.