Recommendations from the Association for European Paediatric and Congenital Cardiology for training in diagnostic and interventional electrophysiology.

The field of electrophysiology (EP) in paediatric cardiology patients and adults with congenital heart disease is complex and rapidly growing. The current recommendations for diagnostic and invasive electrophysiology of the working group for Cardiac Dysrhythmias and Electrophysiology of the Association for European Paediatric and Congenital Cardiology acknowledges the diveristy of European countries and centers. These training recommendations can be fulfilled in a manageable period of time, without compromising the quality of training required to become an expert in the field of paediatric and congenital EP and are for trainees undergoing or having completed accredited paediatric cardiologist fellowship. Three levels of expertise, the training for General paediatric cardiology EP, for non-invasive EP and invasive EP have been defined. This Association for European EP curriculum describes the theoretical and practicsal knowledge in clinical EP; catheter ablation, cardiac implantable electronic devices, inherited arrhythmias and arrhythmias in adults with congenital heart defects for the 3 levels of expertise.

Congenital Lymphatic Malformation and Aortic Aneurysm in a Patient with TSC2 Mutation.

We present a 7-year-old boy with tuberous sclerosis and congenital segmental lymphedema (CSL) of the left leg, as well as two aortic aneurysms. He was treated with everolimus (EVE) since the age of 14 months. His CSL regressed under treatment with EVE. His first aneurysms required operative intervention at age of 17 months. Four months afterward a new aortic aneurysm had been detected above the Dracon graft, but this one remained stable since that time. The patient didn't experience severe side effects. EVE has been well tolerated without disturbance of somatic growth or serious adverse effect.

Arrhythmias in congenital heart disease: a position paper of the European Heart Rhythm Association (EHRA), Association for European Paediatric and Congenital Cardiology (AEPC), and the European Society of Cardiology (ESC) Working Group on Grown-up Congenital heart disease, endorsed by HRS, PACES, APHRS, and SOLAECE.

The population of patients with congenital heart disease (CHD) is continuously increasing with more and more patients reaching adulthood. A significant portion of these young adults will suffer from arrhythmias due to the underlying congenital heart defect itself or as a sequela of interventional or surgical treatment. The medical community will encounter an increasing challenge as even most of the individuals with complex congenital heart defects nowadays become young adults. Within the past 20 years, management of patients with arrhythmias has gained remarkable progress including pharmacological treatment, catheter ablation, and device therapy. Catheter ablation in patients with CHD has paralleled the advances of this technology in pediatric and adult patients with structurally normal hearts. Growing experience and introduction of new techniques like the 3D mapping systems into clinical practice have been particularly beneficial for this growing population of patients with abnormal cardiac anatomy and physiology. Finally, device therapies allowing maintanence of chronotropic competence and AV conduction, improving haemodynamics by cardiac resynchronization, and preventing sudden death are increasingly used. For pharmacological therapy, ablation procedures, and device therapy decision making requires a deep understanding of the individual pathological anatomy and physiology as well as detailed knowledge on natural history and long-term prognosis of our patients. Composing expert opinions from cardiology and paediatric cardiology as well as from non-invasive and invasive electrophysiology this position paper was designed to state the art in management of young individuals with congenital heart defects and arrhythmias.

Radiofrequency Catheter Ablation of Accessory Atrioventricular Pathways in Infants and Toddlers ≤ 15 kg.

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.

Catheter Ablation of Pediatric Focal Atrial Tachycardia: Ten-Year Experience Using Modern Mapping Systems.

Experience of catheter ablation of pediatric focal atrial tachycardia (FAT) is still limited. There are data which were gathered prior to the introduction of modern 3D mapping and navigation systems into the clinical routine. Accordingly, procedures were associated with significant fluoroscopy and low success rates. The aim of this study was to present clinical and electrophysiological details of catheter ablation of pediatric FAT using modern mapping systems. Since March 2003, 17 consecutive patients <20 years underwent electrophysiological study (EPS) for FAT using the NavX(®) system (n = 7), the non-contact mapping system (n = 6) or the LocaLisa(®) system (n = 4), respectively. Radiofrequency was the primary energy source; cryoablation was performed in selected patients with a focus close to the AV node. In 16 patients, a total number of 19 atrial foci (right-sided n = 13, left-sided n = 6) could be targeted. In the remaining patient, FAT was not present/inducible during EPS. On an intention-to-treat basis, acute success was achieved in 14/16 patients (87.5 %) with a median number of 11 (1-31) energy applications. Ablation was unsuccessful in two patients due to an epicardial location of a right atrial focus (n = 1) and a focus close to the His bundle (n = 1), respectively. Median procedure time was 210 (84-332) min, and median fluoroscopy time was 13.1 (4.5-22.5) min. In pediatric patients with FAT, 3D mapping and catheter ablation provided improved clinical quality of care. Catheter ablation may be considered early in the course of treatment of this tachyarrhythmia in symptomatic patients.

Early postnatal high-dose fat-soluble enteral vitamin A supplementation for moderate or severe bronchopulmonary dysplasia or death in extremely low birthweight infants (NeoVitaA): a multicentre, randomised, parallel-group, double-blind, placebo-controlled, investigator-initiated phase 3 trial.

BACKGROUND: Vitamin A plays a key role in lung development, but there is no consensus regarding the optimal vitamin A dose and administration route in extremely low birthweight (ELBW) infants. We aimed to assess whether early postnatal additional high-dose fat-soluble enteral vitamin A supplementation versus placebo would lower the rate of moderate or severe bronchopulmonary dysplasia or death in ELBW infants receiving recommended basic enteral vitamin A supplementation. METHODS: This prospective, multicentre, randomised, parallel-group, double-blind, placebo-controlled, investigator-initiated phase 3 trial conducted at 29 neonatal intensive care units in Austria and Germany assessed early high-dose enteral vitamin A supplementation (5000 international units [IU]/kg per day) or placebo (peanut oil) for 28 days in ELBW infants. Eligible infants had a birthweight of more than 400 g and less than 1000 g; gestational age at birth of 32+0 weeks postmenstrual age or younger; and the need for mechanical ventilation, non-invasive respiratory support, or supplemental oxygen within the first 72 h of postnatal age after admission to the neonatal intensive care unit. Participants were randomly assigned by block randomisation with variable block sizes (two and four). All participants received basic vitamin A supplementation (1000 IU/kg per day). The composite primary endpoint was moderate or severe bronchopulmonary dysplasia or death at 36 weeks postmenstrual age, analysed in the intention-to-treat population. This trial was registered with EudraCT, 2013-001998-24. FINDINGS: Between March 2, 2015, and Feb 27, 2022, 3066 infants were screened for eligibility at the participating centres. 915 infants were included and randomly assigned to the high-dose vitamin A group (n=449) or the control group (n=466). Mean gestational age was 26·5 weeks (SD 2·0) and mean birthweight was 765 g (162). Moderate or severe bronchopulmonary dysplasia or death occurred in 171 (38%) of 449 infants in the high-dose vitamin A group versus 178 (38%) of 466 infants in the control group (adjusted odds ratio 0·99, 95% CI 0·73-1·55). The number of participants with at least one adverse event was similar between groups (256 [57%] of 449 in the high-dose vitamin A group and 281 [60%] of 466 in the control group). Serum retinol concentrations at baseline, at the end of intervention, and at 36 weeks postmenstrual age were similar in the two groups. INTERPRETATION: Early postnatal high-dose fat-soluble enteral vitamin A supplementation in ELBW infants was safe, but did not change the rate of moderate or severe bronchopulmonary dysplasia or death and did not substantially increase serum retinol concentrations. FUNDING: Deutsche Forschungsgemeinschaft and European Clinical Research Infrastructures Network (ECRIN).

Double cryoenergy application (freeze-thaw-freeze) at growing myocardium: lesion volume and effects on coronary arteries early after energy application. Implications for efficacy and safety in pediatric patients.

INTRODUCTION: Data on radiofrequency current application (RFA) at growing myocardium suggest that coronary artery stenosis may occur with a low incidence. Cryoenergy has emerged as an effective alternative to RFA. Although already used in clinical practice, experience with cryoenergy is low due to lack of data concerning effects of a modified double cryoenergy application, a freeze-thaw-freeze cycle, at growing myocardium. Purpose of the study was to assess lesion volume (efficacy) and risk of coronary artery damage (safety) early, 48 hours, after modified double cryoenergy application in a piglet model. METHODS AND RESULTS: In 5 piglets, following selective coronary angiography, two sequential cycles of cryoenergy were delivered at -75 °C for 4 minutes, interrupted by thawing for one minute, at the atrioventricular groove. Piglets were restudied after 48 hours by coronary angiography and intracoronary ultrasound (ICUS). Ablation lesions were examined morphologically and lesion volume was determined by 3-dimensional morphometric analysis. Lesion volume was 109.21 ± 39.61 mm(3) for atrial and 150.30 ± 53.21 mm(3) (P = 0.02) for ventricular lesions. Lesion depth was not significantly different for atrial, 3.07 ± 1.08 mm, versus ventricular lesions, 3.56 ± 1.3 mm. Cryoenergy induced minor coronary artery damage with medial and adventitial necrosis but a preserved intimal layer was present in 2/31 lesions, which had not been detected by coronary angiography or ICUS. CONCLUSION: Early after double cryoenergy application, subclinical minor changes of the coronary artery wall could be detected occasionally whereas the intimal layer remained intact. These findings may have implications on efficacy and safety when cryoenergy is applied for tachycardia substrates in pediatric patients.

Focal atrial tachycardia mimicking catecholaminergic polymorphic ventricular tachycardia: a case report.

Background: In childhood and adolescence, cardiac arrhythmias are often benign in the absence of congenital heart defects. Nevertheless, life-threatening inherited arrhythmogenic syndromes can become clinically manifest in early childhood. As early symptoms may be similar in both conditions, thorough workup is fundamental to avoid delayed diagnosis and misdiagnosis. Case summary: We present the case of a 26-year-old Caucasian female patient who presented with recurrent non-sustained polymorphic wide complex tachycardia. Structural heart disease was excluded by echocardiography as well as cardiac magnetic resonance imaging. Due to wide complex extrasystoles and couplets with alternating QRS axis occurring at low levels of physical exertion, catecholaminergic polymorphic ventricular tachycardia (CPVT) was suspected and further investigated. Epinephrine testing in combination with an electrophysiological (EP) study with placement of a coronary sinus catheter and subsequent programmed stimulation ruled out CPVT and unmasked wide complex tachycardia as varying aberrant conduction of focal atrial tachycardia (FAT). 3D-navigated mapping of FAT revealed a direct parahisian origin. Due to significantly increased risk of atrio-ventricular (AV) block during ablation, the patient refused ablation and preferred medical antiarrhythmic therapy. Discussion: Given the consequences of both, delayed diagnosis and misdiagnosis of CPVT, thorough workup is fundamental. In case of doubt regarding potential aberrant AV conduction in the context of wide complex tachycardia, an invasive EP study may easily and safely prove or rule out aberrancy.

Value of dynamic substrate mapping to identify the critical diastolic pathway in postoperative ventricular reentrant tachycardias after surgical repair of tetralogy of fallot.

UNLABELLED: Characterization of the Critical Isthmus in VT in TOF. INTRODUCTION: The complexity of postoperative ventricular reentrant tachycardias may limit success of catheter ablation. The objective of this analysis was to compare the usefulness of dynamic substrate mapping (DSM) versus color-coded isopotential mapping of the noncontact mapping system for the identification of the critical diastolic pathway of postoperative ventricular reentrant tachycardias (VT) after surgical repair of tetralogy of Fallot (TOF). METHODS: Postoperative VT had been studied applying isopotential maps with the noncontact mapping system EnSite in 7 patients, and radiofrequency current lesion lines had been applied across the shortest isthmus to target during sinus rhythm. Data of the noncontact mapping system were reanalyzed applying the DSM algorithm. For DSM, a 2-Hz filter and color settings between 0 mV and 50% of peak negative voltage (PNV) with autofocus turned off were used. DSM was initially applied over the QRS complex duration during sinus rhythm. Abnormal myocardium was defined as <35-40% of PNV. DSM was subsequently applied to ventricular diastole during the final 33% of VT cycle length. Areas with >70% of PNV within this time frame were to identify the critical diastolic pathway. RESULTS: Applying DSM, the critical diastolic pathway of the VT was identified in all 7 patients that corresponded to the regions targeted for ablation. CONCLUSION: By focusing the time reference to electrical diastole, when the VT wavefront is moving through the low-voltage area, the region of greatest relative voltage could be highlighted, which corresponded to the diastolic pathway. (J Cardiovasc Electrophysiol, Vol. 23, pp. 930-937, September 2012).

A de novo interstitial deletion of 2p23.3-24.3 in a boy presenting with intellectual disability, overgrowth, dysmorphic features, skeletal myopathy, dilated cardiomyopathy.

Interstitial deletions of the distal part of chromosome 2p are rare, with only six reported cases involving regions from 2p23 to 2pter. Most of these were cytogenetic investigations. We describe a 14-year-old boy with an 8.97 Mb deletion of 2p23.3-24.3 detected by array comparative genomic hybridization (array CGH) who had intellectual disability (ID), unusual facial features, cryptorchidism, skeletal myopathy, dilated cardiomyopathy (DCM), and postnatal overgrowth (macrocephaly and tall stature). We compared the clinical features of the present case to previously described patients with an interstitial deletion within this chromosomal region and conclude that our patient exhibits a markedly different phenotype. Additional patients are needed to further delineate phenotype-genotype correlations.

Fate of a modified fenestration of atrial septal occluder device after transcatheter closure of atrial septal defects in elderly patients.

BACKGROUND: Data on closure of atrial septal defects (ASD) in elderly patients with a fenestrated Amplatzer septal occluder (ASO) device is limited. METHODS: A hemodynamically significant ASD was closed with a fenestrated ASO in 3 patients with ages >62 years. Prior to implant a 4-mm fenestration was created by balloon dilatation without additional suture fixation just adjacent to the stent part of the device. Indications for fenestration were restrictive left ventricular physiology and/or pulmonary hypertension. Heparin had been administered during and for 48 hours after the procedure. Two patients were maintained on phenprocoumon because of chronic atrial fibrillation, the remaining patient on aspirin and clopidogrel for 3 months after implant. Transesophageal echocardiography (TEE) and hemodynamic evaluation were performed 4-18 months after ASD closure. RESULTS: A trace or small fenestration through the ASO with left-to-right shunt was detected by TEE in all 3 patients without any hemodynamic significance. No thrombus formation was observed. Pulmonary hypertension improved in the affected patient. Pulmonary arterial wedge pressure and cardiac index improved in the second patient with improvement in heart failure symptoms and of quality of life in both. The third patient, after initial improvement for 6 months, developed significant comorbidities and clinical deterioration at 18 months follow-up. CONCLUSION: The modified fenestration of the ASO decreased significantly in size at follow-up. Applying this technique to selected patients judged to be at risk for ASD closure avoids acute decompensation and allows gradual diminuition of right ventricular volume overload during mid-term follow-up.

[Reversible severe cardiomyopathy caused by a slow permanent tachycardia]. / Reversible, schwere Kardiomyopathie als Folge einer langsamen, permanenten Schmalkomplextachykardie.

Incessant narrow QRS complex tachycardias may result in severe tachycardia-induced cardiomyopathy even if the heart rate during tachycardia is only moderately elevated. The risk of ventricular deterioration is particularly increased in patients with underlying congenital heart disease. In these patients, drug treatment is often insufficient. Thus, catheter ablation of the arrhythmogenic substrate is required in the majority of patients. After successful ablation, ventricular function may recover completely.

Extracorporeal circulation for rewarming in drowning and near-drowning pediatric patients.

Drowning and near-drowning is often associated with severe hypothermia requiring active core rewarming.We performed rewarming by cardiopulmonary bypass(CPB). Between 1987 and 2007, 13 children (9 boys and 4 girls) with accidental hypothermia were rewarmed by extracorporeal circulation (ECC) in our institution. The average age of the patients was 3.2 years. Resuscitation was started immediately upon the arrival of the rescue team and was continuously performed during the transportation.All patients were intubated and ventilated. Core temperature at admission ranged from 20 to 29°C (mean 25.3°C). Connection to the CPB was performed by thoracic (9 patients) or femoral/iliac means (4 patients). Restoration of circulation was achieved in 11 patients (84.6%). After CPB termination two patients needed an extracorporeal membrane oxygenation system due to severe pulmonary edema.Five patients were discharged from hospital after prolonged hospital stay. During follow-up, two patients died(10 and 15 months, respectively) of pulmonary complications and one patient was lost to follow-up. The two remaining survivors were without neurological deficit.Modes of rewarming, age, sex, rectal temperature, and serum electrolytes did not influence mortality. In conclusion,drowning and near-drowning with severe hypothermia remains a challenging emergency. Rewarming by ECC provides efficient rewarming and full circulatory support.Although nearly half of the children may survive after rewarming by ECC, long-term outcome is limited by pulmonary and neurological complications.

Overlap of Moebius and oromandibular limb hypogenesis syndrome with gastroschisis and pulmonary hypoplasia.

The oromandibular limb hypogenesis syndromes (OLHS) represent a group of rare conditions characterized by congenital malformations involving the tongue, mandible, and limbs. There is considerable overlap between the syndromes gathered under the term OLHS, and a marked variability of face and limb anomalies as well as additional malformations. In this report we describe a girl with gastroschisis and pulmonary hypoplasia in addition to features of Moebius syndrome comprising hypoplasia of the tongue and mandible, brachydactyly of halluces, cranial nerve palsies with bilateral facial paralysis and an inability to execute horizontal eye movements. Karyotyping and array-based comparative genomic hybridization were normal. This observation confirms an overlap between Moebius syndrome and OLHS and widens the spectrum of associated malformations. Intrauterine environmental factors including vascular insufficiency, high maternal fever, and drug abuse are likely to play a crucial role in the pathogenesis of this condition.

Cryoablation at growing myocardium: no evidence of coronary artery obstruction or intimal plaque formation early and late after energy application.

BACKGROUND: Animal studies and clinical observations have demonstrated that radiofrequency current application at growing myocardium may result in coronary artery obstruction. Recently, cryoenergy has emerged as an effective alternative to radiofrequency ablation of arrhythmogenic substrates in pediatric patients. Up to now, there has been a lack of experimental data concerning the effects of cryoenergy application at growing myocardium. METHODS: During general anesthesia, selective coronary angiography of the right and left coronary artery was performed in 10 piglets (age: 6 weeks, body weight: 14-18 kg). Subsequently, cryoenergy was delivered at -75 degrees C for 4 minutes using a 7-F catheter with a 6-mm-tip electrode at the atrial aspect of the tricuspid valve annulus in a posterior and lateral position. Additional cryoenergy lesions were induced via a retrograde approach at the lateral and posterior atrial and ventricular aspect of the mitral valve annulus, respectively. Five animals were restudied after 48 hours by coronary angiography and intracoronary ultrasound and in the remaining five piglets after 3 and 6 months, respectively. RESULTS: Selective coronary angiography and intracoronary ultrasound studies did not demonstrate any evidence for coronary artery obstruction after 48 hours, 3 months, or 6 months after cryoenergy application. In addition, histological examinations of the cryolesions after 48 hours and after 6 months did not demonstrate any intimal proliferations of the coronary arteries, respectively. CONCLUSIONS: By means of the present study, we did not observe any affection of the coronary arteries after cryoenergy application at growing myocardium in young piglets.

Mechanical aortic valve replacement in children and adolescents after previous repair of congenital heart disease.

Due to improved outcome after surgery for congenital heart defects, children, adolescents, and grown-ups with congenital heart defects become an increasing population. In order to evaluate operative risk and early outcome after mechanical aortic valve replacement (AVR) in this population, we reviewed patients who underwent previous repair of congenital heart defects. Between July 2002 and November 2008, 15 (10 male and 5 female) consecutive patients (mean age 14.5 +/- 10.5 years) underwent mechanical AVR. Hemodynamic indications for AVR were aortic stenosis in four (27%), aortic insufficiency in eight (53%), and mixed disease in three (20%) after previous repair of congenital heart defects. All patients had undergone one or more previous cardiovascular operations due to any congenital heart disease. Concomitant cardiac procedures were performed in all of them. In addition to AVR, in two patients, a mitral valve exchange was performed. One patient received a right ventricle-pulmonary artery conduit replacement as concomitant procedure. The mean size of implanted valves was 23 mm (range 17-29 mm). There were neither early deaths nor late mortality until December 2008. Reoperations were necessary in five (33%) and included implantation of a permanent pacemaker due to complete atrioventricular block in two (15%), mitral valve replacement with a mechanical prosthesis due to moderate to severe mitral regurgitation in one (7%), aortocoronary bypass grafting due to stenosis of a coronary artery in one (7%), and in one (7%), a redo subaortic stenosis resection was performed because of a secondary subaortic stenosis. At the latest clinical evaluation, all patients were in good clinical condition without a pathological increased gradient across the aortic valve prosthesis or paravalvular leakage in echocardiography. Mechanical AVR has excellent results in patients after previous repair of congenital heart defects in childhood, even in combination with complex concomitant procedures. Previous operations do not significantly affect postoperative outcome.

Value of Regular Defibrillation Threshold Testing After Extracardiac Implantable Cardioverter Defibrillator Placement in Small Children During Mid-Term Follow-Up.

OBJECTIVES: The purpose of this study was to analyze course of defibrillation threshold (DFT) with growth. BACKGROUND: Data on regular DFT testing after extracardiac implantable cardioverter-defibrillator (ICD) placement in infants and small children is still limited. METHODS: An extracardiac ICD was placed in 23 pediatric patients (median age 6.1 years; median body weight 21 kg, median length 120 cm). The defibrillator lead was tunneled pleurally, and the device was placed as "active can" in the right upper abdomen or in a horizontal position between the diaphragm and the pericardium, respectively. DFT was verified intraoperatively, 3 months later, and every 12 months thereafter. The aim was to achieve DFT <15 J allowing ICD programming with a double safety margin above DFT. RESULTS: In all 23 patients, an intraoperative DFT <15 J could be accomplished. Serial DFT testing showed an increase from a median DFT of 10 J intraoperatively to 15 J after 1 year. During mean follow-up of 2.0 years, a significant correlation between DFT and body length, but not body weight, was observed. In 4 of 23 (17%) patients, surgical revision was required because of a DFT increase >20 J during regular DFT testing. No complications regarding DFT testing were noted. CONCLUSIONS: After extracardiac ICD placement in infants and small children, DFT increase related to body length was evident during mid-term follow-up. Routine serial DFT testing was a safe procedure and identified a significant DFT increase in 4 of 23 patients. Serial DFT testing during follow-up in these patients is recommended.

Long-Term Follow-Up After Catheter Ablation of Atrioventricular Nodal Reentrant Tachycardia in Children.

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.