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Tachycardia is characterized by high beating rates that can lead to life-threatening fibrillations. Mutations in several ion-channel genes were implicated with tachycardia; however, the complex genetic contributors and their modes of action are still unclear. Here, we investigated the influence of an SCN5A gene variant on tachycardia phenotype by deriving patient-specific iPSCs and cardiomyocytes (iPSC-CM). Two tachycardia patients were genetically analyzed and revealed to inherit a heterozygous p.F1465L variant in the SCN5A gene. Gene expression and immunocytochemical analysis in iPSC-CMs generated from patients did not show any significant changes in mRNA levels of SCN5A or gross NaV1.5 cellular mislocalization, compared to healthy-derived iPSC-CMs. Electrophysiological and contraction imaging analysis in patient iPSC-CMs revealed intermittent fibrillation-like states, occasional arrhythmic events, and sustained high-paced contractions that could be selectively reduced by flecainide treatment. The patch-clamp analysis demonstrated a negative shift in the voltage-dependent activation at the patient-derived iPSC-CMs compared to the healthy control line, suggestive of a gain-of-function activity associated with the SCN5A(+/p.F1465L) variant. Our patient-derived iPSC-CM model recapitulated the clinically relevant characteristics of tachycardia associated with a novel pathogenic SCN5A(+/p.F1465L) variant leading to altered Na+ channel kinetics as the likely mechanism underlying high excitability and tachycardia phenotype.

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.

In this study, we aimed to evaluate the clinical aspects, electrophysiological studies, and ablation results of permanent junctional reciprocating tachycardia in children.The study comprised 29 pediatric patients diagnosed with permanent junctional reciprocating tachycardia between 2011 and 2021 in 2 pediatric electrophysiology centers. From the file records, the basic demographic characteristics of the patients, as well as electrocardiographic and echocardiographic findings, were acquired retrospectively. The medical treatment and responses of the patients throughout follow-up, as well as the electrophysiological study and ablation data of the patients who had electrophysiological study, were assessed.The mean age at diagnosis of the patients was 3.13 ± 4.43 (0-18) years and the mean weight was 18.22 ± 19.68 (3.8-94) kg. Eighteen patients (62.1%) were girls. Eleven patients (38%) developed tachycardia-induced cardiomyopathy. Tachycardia was incessant in 15 patients (51.7%). In total, 22 patients required 26 ablation procedures. Tachycardia-induced cardiomyopathy and multidrug-resistant tachycardia were the most prevalent indications for ablation. The right posteroseptal pathway was detected in 18 patients (81.8%). The acute procedure success rate was 100% (22/22). The recurrence rate was 18% (4/22) and 3 of them underwent successful ablation again. The overall success percentage was 95.4% (21/22). None of the patients had any complications. The mean follow-up period was 4.39 ± 3.05 years.Although permanent junctional reciprocating tachycardia is uncommon, it is often persistent, resistant to medical treatment, and associated with a substantial risk of tachycardia-induced cardiomyopathy. Catheter ablation can be performed on these patients at any age, with minimal risk of complications and a high success rate. It is crucial to keep monitor of the patients' recurrence.

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.

QT surveillance is the most vital appliance to detect the possibility of sudden death sourced by using pro-arrhythmic drugs treating abnormal conditions in the heart. The repolarization of ventricles makes QT interval surveillance difficult since noisy conditions and individual cardiac situations. Besides, an automated QT algorithm is crucial due to a manual QT measurement with some disadvantages such as fatigue condition in reading long records. In this study, a fully novel automated method combining Continuous Wavelet Transform and Philips method was established to perform QT interval analysis. Electrocardiogram recordings were obtained from PhyisoNet database marked by manual and standard automated methods. The proposed algorithm had scores of 15.46 and 11.87 millisecond mean error with 11.85 and 9.91 millisecond standard deviation in terms of gold and silver standards, respectively. Also, the entire QT database was utilized in order to test the algorithm performance with the score of 12.89 and 9.76 millisecond mean and standard deviation errors, respectively. The present algorithm performance had scores of −0.21 ± 7.81 at golden standard, and −4.10 ± 18.21 millisecond error for the whole QT database tests, respectively. The proposed algorithm is attained to more stable and robust results with a higher performance than the previous comparable studies.

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.

Objectives: This study assesses the competency of pediatricians in interpreting electrocardiograms (ECGs). Methods: A cross-sectional study involving 125 pediatricians comprised of 71 general pediatricians, 15 pediatric cardiologists, and 39 other subspecialists recruited from all public hospitals and two specialty centers. Participants completed a questionnaire that included 10 ECGs and questions regarding backgrounds, attitudes, and practices. The ECGs were graded to obtain a knowledge score out of 30 points. Mann–Whitney U test and Kruskal-Wallis test with post hoc analysis and Bonferroni adjustment were used to compare groups. Results: The mean knowledge score ranged from 47.7% to 69.7% among various pediatric specialties (P = 0.006). Age, increasing years of experience, confidence level, number of cardiology referrals, and perceived importance of having good ECG interpretation skills were significantly related to the knowledge score (P ≤ 0.05). Accuracy was highest in identifying normal ECGs (76.8%), supraventricular tachycardia (64.8%), along with long QT interval (58.4%), and was lowest for right bundle branch block (RBBB) (10.4%), 2:1 atrioventricular conduction (10.4%), and atrial tachycardia (AT) (4.8%). Accuracy among pediatric cardiologists was highest for long QT interval (100%), normal ECG (80%), as well as Wolff-Parkinson-White syndrome (80%), and lowest for RBBB (13.3%) and AT (0%). Most pediatricians believe that ECGs are “useful” (78.4%) and that having good interpretation skill is “important” (80.6%). Conclusions: Pediatricians recognize the importance of ECGs. However, their skill and level of accuracy at interpretation is suboptimal, including cardiologists, and may affect patient care. Thus, efforts should be made to improve ECG understanding to provide better service to patients.

Objective: Optimal management in asymptomatic children and adolescents with the Wolff-Parkinson-White (WPW) electrocardiographic pattern is still debatable. The aim of this retrospective study was to evaluate the electrophysiological properties of asymptomatic children and adolescents with WPW. Methods: The medical records and procedural data of asymptomatic children and adolescents with the WPW electrocardiographic pattern who underwent invasive electrophysiological study (EPS) and catheter ablation between April 2012 and April 2018 were evaluated. Results: In all, 149 consecutive, asymptomatic children and adolescents with WPW who underwent EPS were retrospectively investigated. In 39 (26.2%) of the patients, a shortest pre-excited R–R interval of ≤250 ms during atrial fibrillation or an accessory pathway effective refractory period of ≤270 ms was found. A total of 39 patients with high-risk antegrade conduction and 45 patients with inducible orthodromic atrioventricular re-entrant tachycardia underwent catheter ablation. In addition, 14 patients underwent catheter ablation due to family preference. Conclusion: High-risk antegrade conduction properties are exhibited by more than one-quarter of asymptomatic children and adolescents with WPW. Ablation should be considered as a first-line therapy in asymptomatic children and adolescents with high-risk WPW.

Introduction:Catheter ablation of left posterior fascicular ventricular tachycardia in the pediatric population remains challenging, and most studies about this topic have been conducted on adult patients. This study aimed to assess the clinical presentation features and outcomes of catheter ablations performed using limited fluoroscopy with three-dimensional electroanatomic mapping system guidance in a pediatric left posterior fascicular ventricular tachycardia patient group.Methods:A total of 20 consecutive patients undergoing left posterior fascicular ventricular tachycardia ablation at a single tertiary centre were enrolled. All children with left posterior fascicular ventricular tachycardia underwent electrophysiological studies using the EnSite NavX system guidance. Ablations were performed during the sinus rhythm based on the Purkinje potentials in all patients.Results:The mean patient age was 12.7 years (range 2–16), and the mean patient weight was 51 kg (range 11–84). The mean procedure and median fluoroscopy times were 143.1 minutes and 3.4 minutes, respectively. No fluoroscopy was used in three patients. Acute success was achieved in 19 patients (95%). During a mean follow-up of 38.6 ± 19.35 months, left posterior fascicular ventricular tachycardia recurred in four patients (20%). Repeat ablations were performed successfully in those patients who developed recurrences. No complications were seen.Conclusions:Catheter ablation of left posterior fascicular ventricular tachycardia in children can be performed safely and effectively with low fluoroscopy exposure using a three-dimensional electroanatomic mapping system.

WOS: 000463707500017 PubMed ID: 30729261 Transseptal puncture (TP) is used in pediatric patients to access the left atrium in left-sided arrhythmia catheter ablation. Performing this procedure can be difficult and risky, especially in small children. In this study, we aimed to evaluate the safety and feasibility of TPs in children 20kg and

WOS: 000445208600021 PubMed ID: 29882187 In Ebstein's anomaly (EA), tachycardia substrates are complex, and accessory pathway (AP) ablations are often challenging. This study demonstrates the utility of the EnSite Velocity system (St. Jude Medical, St Paul, MN) in the catheter ablation of supraventricular tachycardia in children with EA. Twenty patients [Female/Male=8/12, median age 11.5years (2.6-18)] with EA who underwent catheter ablation guided by the EnSite Velocity system between December 2011 and December 2016 were retrospectively evaluated. Five patients had severe EA, and two of them were at Fontan palliation pathway. The most common indications for ablations were palpitations/syncope and treatment-resistant arrhythmias. Thirty-one tachycardia substrate foci (21 manifest AP, 2 concealed AP, 4 Mahaim AP, 3 focal atrial tachycardias, and 1 typical atrioventricular nodal reentrant tachycardia) were detected in 20 patients. There were multiple tachycardia substrates in 11 patients (55%). The patient-based acute procedure success rate was 19/20 (95%), and the tachycardia-based success rate was 30/31 (97%). The mean procedure time was 170 +/- 43min (90-265). Fluoroscopy was not used in 15 (75%) patients. The mean fluoroscopy time in the remaining five patients was 3.6 +/- 2.9min (0.7-7.8). During a mean follow-up of 35.1 +/- 20.3months (6-60), tachycardia recurred in four patients (4/19, 21%). No complications were seen. Catheter ablation of arrhythmias can be performed effectively and safely in pediatric EA patients by using a limited fluoroscopic approach with the help of electroanatomical mapping systems. However, the rate of tachycardia recurrence at follow-up remains high.

Background Cryoablation is increasingly utilized in children because of its safety profile. Recently, larger catheter tips have been more widely used to improve long-term success rates. The aim of this study was to assess the safety and efficacy of 8-mm-tip catheters for cryoablation of right-sided accessory pathways (APs) in children. Methods Electrophysiological procedures were performed using the EnSite™ system (St. Jude Medical Inc., St. Paul, MN, USA). Results Between July 2010 and July 2014, 54 patients (mean age: 13.1 ± 3.7 years) underwent cryoablation using an 8-mm-tip catheter. In 18 of 54 (33%) patients where an 8-mm-tip catheter was the first-choice catheter, the success rate was 18 of 18 (100%). There was a history of previous failed attempts or recurrence with radiofrequency ablation and/or 6-mm-tip cryoablation in 36 of 54 (67%) patients. The success rate in these patients was 24 of 36 (67%). No fluoroscopy was used in 34 of 54 procedures. The recurrence rate was six of 42 (14%) during a mean follow-up period of 32 ± 15 months. In one patient, transient atrioventricular block occurred. Conclusions Cryoablation with an 8-mm-tip catheter for right-sided APs in children who weigh over 40 kg appears to be safe and acutely effective in cases where conventional ablation methods fail and also as a first choice for ablation procedure. However, the recurrence rate still seems to be high.

WOS: 000387109800019 PubMed ID: 27184808 Introduction Definitive therapy of idiopathic right ventricular arrhythmias (VA) remains a challenge in interventional electrophysiology. The aim of this study was to evaluate the utility of EnSite Velocity system in the catheter ablation of RV tachycardia in children. Methods Thirty-five children with idiopathic right VA underwent catheter ablation procedure using the EnSite Velocity system guidance. Results The mean patient age was 12.0 +/- 3.7 years and the mean patient weight was 43.6 +/- 18.7 kg. The origin of right VA was divided into right ventricular outflow tract (RVOT) (30 patients) and other right ventricular localizations (five patients). The mean procedure and fluoroscopy times were 175 +/- 67 min and 2.35 +/- 1.89 min, respectively. No fluoroscopy was used in 19 patients. Acute success was achieved in 29 patients (83 %). The focus of VA was epicardial in three failed procedures. Cryocatheter (6-mm or 8-mm tip) was used in six patients, radiofrequency ablation (RFA) (4-mm or 8-mm tip) in 26 patients, and 4-mm tip irrigated RFA in three patients. During a mean follow-up of 15.9 +/- 7.1 months, ventricular tachycardia recurred in six patients (20 %). There were three complications (transient atrioventricular block developed in one patient during parahissian cryoablation and two patients developed transient complete right bundle branch block). Conclusions Catheter ablation of idiopathic right VA in children can be performed safely and effectively with limited fluoroscopy using the EnSite Velocity system.

WOS: 000471631500014 PubMed ID: 30603855 PurposeCatheter ablation is the only choice of treatment in some small children with medically refractory supraventricular tachycardia (SVT). Electroanatomical mapping systems (EMS) are more commonly utilized in electrophysiological procedures in recent years, which resulted in a significant decrease in fluoroscopy exposure. The potential benefit of EMS in small children has not been studied. Therefore, we investigated the outcomes of children undergoing catheter ablation weighing 20kg using an electroanatomical mapping system.MethodsThis study evaluated the outcomes, characteristics, and follow-ups of children 20kg who underwent SVT ablations between April 2012 and April 2018 in a pediatric electrophysiology center where EMS were routinely used.ResultsIn a 6-year period, 1129 children underwent SVT catheter ablation under EMS guidance at our institution. A total of 84 of them were weighing 20kg. The acute success rate was 97.6% in 85 tachycardia substrates. No fluoroscopy was used in 58 of the patients, while a median of 5 (4-14)min of fluoroscopy was used in the remaining 26 patients. Recurrences were seen in 4 patients (4.8%) at a mean follow-up of 3.892.08years. Five patients developed non-vital complications (2 right bundle block and 3 temporary complete block that spontaneously resolved during the procedure). Conclusions The outcome of catheter ablation with the guidance of EMS for the treatment of SVT in small children is favorable. Fluoroscopy exposure can be decreased and even eliminated in most patients.

WOS: 000462873900008 PubMed ID: 30740745 Introduction Atrial tachycardia (AT) is an uncommon cause of supraventricular tachycardia in children and it is often resistant to medical therapy. Catheter ablation can be curative in children with AT. However, experience of ablation of pediatric AT is still very limited. The aim of this study, which is the largest series from a single center, was to assess the efficacy and safety of ablation of AT using an electroanatomical-mapping system. Methods It was a retrospective review of 39 children with AT who underwent catheter ablation procedure using the EnSite Velocity system (St. Jude Medical, St. Paul, MN, USA) between July 2012 and April 2017. Results The mean patient age was 13.32 +/- 6.82 years. The location of AT was right sided in 25 and left sided in 13, and both sides in one patient. The mean procedure time was 184.23 +/- 60.19 min. Fluoroscopy was not used in 25 of 39 patients. The mean fluoroscopy time in the remaining patients was 5.53 +/- 5.22 min. Radiofrequency (RF) ablation was used in 22, cryoablation was used in 10, and both RF and cryoablation were used in seven. Acute success was achieved in 34 patients (87.2%). During a mean follow-up of 51.35 +/- 12.62 months, AT recurred in five patients. These patients underwent second ablation procedures and four of them were successful. Final success was achieved in 33 out of 39 patients (84.6%). There were no complications except for one patient who had an uneventful pericardial needle injury during transseptal puncture without effusion. Conclusions Catheter ablation of AT in children can be performed safely and effectively with a limited fluoroscopy using electroanatomical mapping systems. Medipol University This work was supported by Medipol University through its institutional facilities.

Background In this study, we reported our experience with the use of cardiac event recorders in pediatric patients. Methods We evaluated 583 patients fitted with an event recorder (15–30 days) between March 2010 and November 2014 at our clinic. Excluded from the study were 117 patients with no recorded events and six with records contaminated by electrocardiogram artifacts. All of the patients received electrocardiograms, Holter monitoring, and echocardiography before the cardiac event recording. Results The patient sample consisted of 460 patients (64% female). The mean age was 12.8 ± 4.1 years. The median number of recorded events was 7. The indications included palpitations in 336 (73%) patients, syncope in 27 (6%) patients, and chest pain and palpitations in 97 (21%) patients. Whereas 64 patients (14%) had structural heart disease according to echocardiographic examination, the remaining patients had normal echocardiographic examination results. The most frequent cardiac comorbidities were mitral valve prolapse (6%), operated tetralogy of Fallot (1.5%), and complicated congenital heart diseases with single ventricle physiology (1%). The recorded events were sinus tachycardia in 113 (25%) patients, supraventricular tachycardia in 35 (8%) patients, ventricular extrasystole in 20 (4%) patients, supraventricular extrasystole in nine (2%) patients, and ventricular tachycardia in two (0.4%) patients. Based on the event recorder and follow-up electrocardiogram findings, 46 patients received an electrophysiology study/ablation. The symptom-rhythm correlation was 39%. Conclusion In the presence of possible arrhythmia-related symptoms in children, a cardiac event recorder can be considered a useful primary diagnostic method. More research on this topic is needed.

Background The aim of this study was to examine the effects of atomoxetine on heart rhythm using 12-lead electrocardiography (ECG) and 24 h Holter monitoring. Methods Children and adolescents who were diagnosed with attention deficit–hyperactivity disorder according to DSM-IV-TR were referred to a pediatric cardiology clinic for cardiologic examination before and after 4 or 5 weeks of atomoxetine treatment. Cardiac examination, complete blood count, biochemistry, thyroid function tests, 12-lead ECG and 24 h Holter monitoring were performed routinely in all patients. Each subject underwent 24 h Holter ECG monitoring before atomoxetine was started and after 4 or 5 weeks of effective dose atomoxetine treatment. Results Forty-one patients were included in this prospective study. No statistically significant change was found in QT, QTc or QT interval dispersion or blood pressure before and after 4 or 5 weeks of atomoxetine treatment. There was a statistically significant increase in heart rate (both during the day and at night) and QRS duration, and a statistically significant decrease in P wave dispersion. Three patients had rhythm disturbances. All of these three patients were asymptomatic and none of these arrhythmias reached clinical significance. Conclusion Atomoxetine did not cause significant changes in ECG or Holter variables. In two patients, who had undiagnosed subclinical extrasystoles, extra beats were increased after 4th week of treatment, but still remained clinically insignificant. Before and after atomoxetine treatment, listening to the heart sounds for a longer time, may help clinicians to notice an extra beat. If an extra beat is identified then 24 Holter monitoring is recommended.

WOS: 000357683800028 PubMed ID: 25946984 Cardiac interventions with fluoroscopy during pregnancy carry significant risks for the fetus. This report reviews three pregnant patients: two of them requiring pacemaker implantation and one underwent diagnostic cardiac catheterization without fluoroscopy. The cases were performed using EnSite system (St. Jude Medical Inc., MN, USA) guidance. The necessary cardiac structure geometries were reconstructed with a deflectable quadripolar electrophysiology catheter without fluoroscopy. In two cases, pacemaker leads were connected to the EnSite system for navigation and fixation of leads. In the third case, long sheaths and electrophysiology catheters were used to access the right ventricle and pulmonary artery. Transthoracic echocardiography was also used in all three cases. A 31-year-old woman at 8-week pregnancy was admitted with ventricular septal defect and significant pulmonary hypertension. The patient underwent catheterization to assess for the risk of continuation of pregnancy. There was partial reactivity, it was decided not to terminate the pregnancy, and an uneventful delivery was succeeded at 35 weeks of gestation without complications. The rest of the two pregnant patients were a 28-year-old pregnant woman at 14 weeks of gestation and a 40-year-old woman at 12-week gestation. Both of them presented with symptomatic complete AV block. A single-chamber pacemaker was implanted in the first one, and a dual-chamber pacemaker was implanted in the latter. Pregnancy continued in both without complications. Successful cardiac catheterization and pacemaker implantation can be performed safely in selected pregnant patients using an electroanatomic mapping system guidance without fluoroscopy.

Background Syncope is a frequent complaint in children and adolescents and may be a significant sign of serious pathology. Although patient history, family history, and physical examination are sufficient to reach a diagnosis in most cases of syncope, the cause of syncope still cannot be determined after initial investigation in one-third to half of all patients. The aim of this study was to evaluate the diagnostic yield of implantable loop recorder (ILR) in children with unexplained syncope. Methods A retrospective review was carried out of clinical data, indications, findings, and a final management strategy in patients who underwent ILR implantation. Results A total of 12 patients with a mean age of 9.4 ± 4.5 years underwent ILR (Reveal Plus; Medtronic) implantation. ILR implantation indication was syncope in all of the patients. Family history, routine cardiac assessment, including resting 12-lead electrocardiogram, transthoracic echocardiography, 24 h Holter recording, and event recorder findings, were normal with the exception of one patient with (previously corrected) tetralogy of Fallot. After an average of 20 months (range, 1–36 months), six patients developed symptoms. ILR memory showed torsades de pointes–ventricular fibrillation (n = 3), catecholaminergic polymorphic ventricular tachycardia (n = 1), asystole and ventricular tachycardia (n = 1), and normal sinus rhythm (n = 1). At the time of writing six patients were still in follow up with no symptoms after an average of 25.2 months. Conclusion Implantable loop recorder plays an important role in the diagnosis of life-threatening arrhythmias in which syncope is otherwise unexplained. ILR implantation should be remembered in children whose symptoms are strongly correlated with rhythm disturbances.

Background We present the early results of looped epicardial cardioverter defibrillator coil implantation on the anterior surface of right ventricular outflow tract in infants and children. Methods Patients with a surgical history of an epicardial implantable cardioverter defibrillator system between 2013 and 2014 were included in the study. Patient age, gender, body weight, indications for a cardioverter defibrillator system implantation, defibrillation threshold values, and defibrillation therapies were retrospectively evaluated. Results There were eight patients with a mean age of 4.4 ± 2.9 years and a mean body weight of 19.5 ± 11.7 kg. Five of the patients had been diagnosed with long QT syndrome, one patient had been diagnosed with genetic channelopathy and noncompaction of the left ventricle, and two patients had been diagnosed with univentricle physiology. The implantable cardioverter defibrillator system was composed of pace-sense leads, an abdominal active can, and a defibrillation coil placed below the pulmonary valve annulus on the anterior surface of the heart. The mean defibrillation threshold was 6.6 ± 2.3 joules. There were four appropriate therapies in two patients in a mean follow-up of 9 ± 6.5 months. Conclusion The significantly low defibrillation thresholds with the defibrillation coils located below the pulmonary valve annulus are encouraging. However, a larger patient series will be necessary to evaluate the safety and reliability of this technique. doi: 10.1111/jocs.12525 (J Card Surg 2015;30:376–380)

WOS: 000426870600005 PubMed ID: 29318633 BackgroundAtrioventricular nodal reentrant tachycardia (AVNRT) is a common tachyarrhythmia substrate inchildren, which is successfully treated by catheter ablation using radiofrequency or cryothermal energy. In recent years, cryoablation (Cryo) using electroanatomical system guidance is more commonly preferred for use in children in order to decrease the risk of an atrioventricular block. However, there are concerns regarding the long-term efficacy of Cryo in treating AVNRT. We aimed to evaluate the feasibility, safety, and long-term efficacy of Cryo for AVNRT in children. Methods and resultsA total of 275 consecutive children above 4 years of age diagnosed with AVNRT were included in our study. The EnSite system (St. Jude Medical, Inc., St. Paul, MN, USA) was used to reduce or eliminate fluoroscopy. The study included 275 patients (148 females, age: 11.9 3.6 years) undergoing catheter ablation forAVNRT from July 2012 to September 2016. Acute success was obtained in all (100%) patients with a mean procedure time of 140 +/- 44 minutes. Fluoroscopy was used in only 12 (4.4%) patients. During a follow-up time of 25.6 +/- 13.5 months (median: 23 months),AVNRT recurred in 12 of 279 (4.4%) of the patients. Age, sex, number of Cryo lesions, and catheter tip size (6-mm vs 8-mm) were not predictive for recurrence. In nine patients, a repeat ablation was successfully performed with cryoenergy. ConclusionsCryo for AVNRT is a safe and effective procedure with excellent long-term outcomes. The use of electroanatomical systems during ablation significantly decreases exposure to fluoroscopy without compromising success.

Background The presence of Mahaim accessory pathways (MAP) with anterograde decremental conduction is a disorder that leads to antidromic atrioventricular reentrant tachycardia. There are rare reports of cryoablation use in MAP. This study aims at sharing our experience with using cryoablation to treat MAP in children. Methods Electrophysiology study and catheter ablation were performed in 14 patients diagnosed with Mahaim tachycardia between January 2010 and December 2013. Cryoablation was used in nine of the cases. A three-dimensional navigation system with surface electrode patches (EnSite System, St. Jude Medical Inc., St. Paul, MN, USA) was used for all procedures. Results The patients (two girls and seven boys) had a median age of 11.5 years (8–18 years) and a median weight of 67 kg (31–80 kg). Mahaim conduction was localized in the right posterolateral (n = 4), right lateral region (n = 2), right posteroseptal (n = 1), right anterolateral (n = 1), and right anterior (n = 1). A pathway potential was noted in six of nine cases at the tricuspid annulus. Catheter choices and acute success rates were as follows: cryoablation in four (three of four successful), radiofrequency catheter ablation (RFA) and cryoablation in five (successful in four of five). No fluoroscopy was used in six of nine patients. The mean procedure duration was 249 ± 90 minutes. No major complications were observed. The final long-term success rate for cryoablation was seven of nine (78%). Conclusions Cryoablation can be used as a reliable and effective alternative to RFA in the treatment of Mahaim accessory conduction pathways in children. Prospective comparative studies are necessary in order to further evaluate the long-term efficacy of this method.

Background Radiofrequency (RF) catheter ablation in the septal arrhythmia substrates has an increased risk of irreversible atrioventricular block. Despite its safety profile, several studies reported a lower acute success rate and a higher recurrence rate with cryoablation of septal accessory pathways (APs) when compared to RF ablation. The aim of this study was to assess the efficacy and safety of cryoablation of right septal APs using an electroanatomical mapping system guidance. Methods and Results A total of 43 consecutive patients (13.2 ± 5.5 years) underwent cryoablation for right septal APs. The EnSite system (St. Jude Medical, St. Paul, MN, USA) was used in all procedures. No fluoroscopy was used in 90% of patients (39/43). The mean fluoroscopy time in the remaining four patients was 3.7 ± 0.7 minutes. An electrophysiology catheter with 2-mm distal spacing was used to determine the precise AP location. The majority of the patients (20/43) had anteroseptal, and remaining of the patients had posteroseptal (15/43) and midseptal (8/43) APs. A 6-mm-tip catheter was used in 33 patients and 8-mm-tip catheter was used in nine patients (both catheters were used in one patient). The mean procedure duration and number of complete cryoablation lesions were 181.5 ± 60.6 minutes and 6.1 ± 3.1 minutes, respectively. Acute success was achieved in 40 of 43 patients (93%). No complications were noted. During a mean follow-up of 8.8 ± 4.8 months, five patients (12.5%) experienced recurrence. Conclusions Our data suggest that cryoablation of septal APs can be performed safely with comparable efficacy to the reported RF ablation results using a limited fluoroscopy approach.

Background: Early-onset transient atrioventricular block (AVB) is a rare occurrence following cryoablation of atrioventricular nodal reentrant tachycardia (AVNRT), despite lack of any AVB at the end of the procedure. The purpose of this prospective study was to assess AVB shortly after successful cryoablation of AVNRT in children. Methods: A 6-mm-tip cryocatheter was used in 39 procedures. An 8-mm-tip catheter was used in 11 procedures. Twelve-lead electrocardiograms (ECGs) and 24-hour ambulatory ECGs were performed 24 hours prior to the procedure and immediately following the procedure. All procedures were done using the EnSite system (St. Jude Medical, St. Paul, MN, USA) without fluoroscopy. Results: Although nine (18%) patients developed variable degrees of transient AVB during the procedure, all of them had normal atrioventricular (AV) conduction at the end of the procedure and did not require any intervention. Four of these patients had variable degrees of transient AVB following the procedure despite having normal AV conduction at the end of the procedure. One developed Mobitz type I AVB, which lasted for 11.5 hours, and the other three experienced 2:1 AVB, which lasted for 2, 8, and 24 hours, respectively. All patients had complete resolution of the AVB, which was also documented with the 24-hour ambulatory ECGs after the procedure. Conclusion: Early transient AVB can develop following AVNRT cryoablation even if AV conduction is normal at the end of the procedure. Despite the transient AVB in the initial 24 hours after the procedure in some cases, there is no evidence for ongoing AV nodal dysfunction. (PACE 2014; 00:1‐5)

ObjectivesCurative therapy of idiopathic ventricular tachycardia remains a challenge in interventional electrophysiology. The aim of this study was to demonstrate the utility of an EnSite NavX system in the catheter ablation of idiopathic ventricular tachycardia in children.Patients and methodsIn all, 17 children with idiopathic ventricular tachycardia underwent electrophysiological studies using the EnSite NavX system guidance.ResultsThe mean patient age was 13 ± 2.4 years (range: 7.8–17.9) and the mean patient weight was 52.3 ± 11.9 kg (range: 32–75). The origin of ventricular tachycardia was in the right ventricular outflow tract in nine patients, in the left ventricle in six, near the bundle of His/right bundle branch in one, and in the left aortic cusp in one. The mean procedure and fluoroscopy times were 169.3 ± 43.2 minutes and 8 ± 10.8 minutes, respectively. No fluoroscopy was used in six patients. The mean radiation exposure was 33.1 ± 56.4 mGy. Acute success was achieved in 14 patients (82%). The focus of ventricular tachycardia was epicardial in two failed procedures. During a mean follow-up of 8.5 ± 7.6 months, ventricular tachycardia recurred in three patients, two of whom underwent a second procedure. Except for one patient who developed transient right bundle branch block, no complications were seen.ConclusionCatheter ablation of idiopathic ventricular tachycardia in children can be performed safely and effectively with low fluoroscopy exposure using the EnSite NavX system.

Background: The aim of this study was to evaluate the indications, results and complications of radiofrequency ablation (RFA) and transcatheter cryoablation (TCA) in neonates and infants with incessant drug-resistant supraventricular tachycardia (SVT). Methods: Out of 225 patients who underwent RFA and TCA at our center between January 2010 and February 2012, 5 patients under the age of 1 (4 male, 1 female) were evaluated. The indication for RFA/TCA was recurrent hemodynamically compromising drug-resistant SVT. Results: Over a 2-year period, 6 ablation procedures were performed in 5 patients. Average patient age was 3.3 ± 3.9 months (12 days – 9.5 months); average patient weight was 5.4 ± 2.2 kg (3.5–9 kg). One patient had ventricular septal defect, 1 had corrected transposition of great arteries, ventricular septal defect, right ventricular hypoplasia and pulmonary hypertension, while 3 had only patent foramen ovale. Electrophysiology study showed 1 accessory pathway in each patient (right posteroseptal in 2, left posteroseptal in 2 and left lateral in 1). The pathway was manifest in 1 patient with Wolff-Parkinson-White syndrome (WPW) and concealed in the rest. Two of the concealed pathways had slow conduction time and decremental properties (the permanent form of junctional reciprocating tachycardia). Two patients underwent TCA and 3 — RFA, with an acute success rate of 100%. In the first week after the procedure, the patient with the complex cardiac anomaly and WPW developed recurrence and underwent ablation again. Four of the procedures were carried out using an electroanatomic mapping system besides fluoroscopy. Average procedure time was 167 min (100–234); fluoroscopy time was 8.2 min (0.7–19.7). None of the patients developed major complications. After the average follow-up period of 6.5 months (3–18), all patients were symptom-free without medication. Conclusions: RFA and TCA can be performed successfully in neonates and infants with incessant medically refractory SVT. (Cardiol J 2013; 20, 3: 241–246)

Background Epicardial implantation of implantable cardioverter defibrillators (ICDs) is considered in the presence of intracardiac shunt, venous access issue, or small body size. We report our experience with epicardial ICD coil implantation using a minimally invasive method. Methods Nine patients who underwent epicardial ICD implantation were included. The median age was 7.4 years (3.9–9.6 years) and the median weight was 15 kg (12–24 kg). Diagnosis at the time of implantation included long QT syndrome (n = 5), catecholaminergic polymorphic ventricular tachycardia (n = 2), hypertrophic cardiomyopathy (n = 1), and fast monomorphic ventricular tachycardia (n = 1). The minimally invasive method involved a subxiphoid incision to place the epicardial pacing leads. The ICD coil was placed in the transverse sinus in four patients using an access path posterior to the heart. The second approach involved a path anterior to the heart to reach the epicardial location posterior to the left atrial appendage in the five remaining patients. No fluoroscopy was used in either approach. The median defibrillation threshold (DFT) at implantation was 7.5 J. Results Lower DFTs were observed in the anterior approach (10 J vs 5 J). Appropriate ICD shocks were observed in three patients during the median 18-month follow-up period (0.3–28 months). No inappropriate shocks were noted. One patient developed pericardial tamponade 39 days after the procedure and was surgically drained. Conclusions Minimally invasive epicardial ICD coil implantation in children with low DFT values is possible. The anterior implantation approach appears superior to the posterior approach.

WOS: 000405798800018 PubMed ID: 28612086 Due to its safety profile, cryoablation (Cryo) for atrioventricular nodal reentrant tachycardia (AVNRT) is more commonly preferred over radiofrequency (RF) ablation in children in recent years. Recent studies demonstrated high long-term success rates comparable to radiofrequency ablation. The aim of this prospective study was to compare the efficacy and safety of an 8-mm-tip versus 6-mm-tip Cryo catheter in the treatment of AVNRT in children. A total of 125 consecutive patients over 10 years of age with AVNRT were included. EnSite system (St. JudeMedical, St Paul, MN, USA) was used to reduce or eliminate fluoroscopy. The acute procedural success was 100% in both groups. The prodecure duration for the 8-mm-tip group was shorter (151.6 +/- 63.2 vs. 126.6 +/- 36.7 min, p < 0.01, respectively). Fluoroscopy was used in only 7 patients. The mean follow-up duration was 14.6 +/- 8.4 months (median 13.5 months, min. 3 months and max. 27 months). The recurrence rate for AVNRT was also comparable between the two groups (6-mm tip: 9.6 vs. 8-mm tip: 8%). Cryo of AVNRT is a safe and effective procedure with comparable acute and mid-term follow-up success rates using 6-mm and 8-mm-tip catheters in children. In addition, procedure duration is shorter with an 8-mm-tip Cryo catheter.

WOS: 000404826700004 Biosensors aim at providing pervasive healthcare by collecting and communicating highly sensitive medical information. Due to their extreme limitations, lightweight and secure key management infrastructures are required. For this reason, biosensors use physiological parameters that are generated from different vital signals (i.e., electrocardiogram, photoplethysmogram, blood pressure) to protect the exchanged private health information. In this paper, we define two novel physiological parameter generation techniques and analyze both the performance and the quality of the outcomes. Our results show that we generate good candidates of physiological parameters that can be used as cryptographic keys to secure the communication among the biosensors. Scientific and Technological Research Council of Turkey (TUBITAK) [114E557] This work was partially supported by the Scientific and Technological Research Council of Turkey (TUBITAK) under grant 114E557 and part of this work was presented in PervasiveHealth 2015 (Altop et al., 2015).

WOS: 000320062000001, PubMed ID: 23686300, Background: The purpose of this study was to examine the effects of carvedilol therapy on autonomic control of the heart and QT-interval dispersion (QTd) among children with idiopathic dilated cardiomyopathy (DCM) whose symptoms were not adequately controlled with standard congestive heart failure therapy. Material/Methods: Patients with DCM who were treated with carvedilol were enrolled in the study. All patients had undergone carvedilol therapy in addition to standard therapy for at least 6 months. Clinical, echocardiographic, and electrocardiographic parameters, and 24-h Holter records of patients were retrospectively evaluated before and after carvedilol treatment. Results: A total 34 patients (mean age: 7.4 +/- 4.3 years) with DCM were analyzed in the study. The median follow-up period was 9.5 months. After the 6 months of carvedilol therapy the clinical score significantly improved, left ventricular ejection fraction (LVEF) and fractional shortening (LVFS) significantly increased, and left ventricle end-diastolic dimensions and end-systolic dimensions significantly decreased. There were statistically significant increases in mean SDNN, SDANN, rMSSD, and pNN50 (p=0.002, p=0.001, p=0.008, and p=0.026, respectively). After the carvedilol therapy, SDNN was correlated with the clinical score, heart rate, LVEF, LVFS, and total premature ventricular contractions (PVCs). In addition, rMSSD and pNN50 were correlated with heart rate, LVEF and LVFS. A significant reduction was observed in QTc-minimum, QTc-maximum, and QTd values (434.9 +/- 40.7 vs. 416.1 +/- 36.5, 497.8 +/- 43.6 vs. 456.3 +/- 41.7, 58.6 +/- 17.1 vs. 49.3 +/- 15.6; p

Background: The clinical spectrum of Brucella infection is quite diverse and characterized by multi-system involvement. Patients present with myocarditis, endocarditis, or pericarditis. Infective endocarditis is the most common cardiovascular complication in patients with brucellosis. Although conduction abnormalities are seen in cases with endocarditis, they are reported very rarely in the setting of cardiac Brucella infection. Case Report: An eight and a half-year-old male patient was referred to our clinic due to inadequate response to cotrimaxazole plus streptomycin treatment at the 15th day of admission. Although local hospital records on the patient showed a heart rate of 80 bpm, we determined a heart rate of 46 bpm. The electrocardiogram showed complete atrioventricular (AV) block. The average heart rate was determined as 48 bpm with 24-hour Holter electrocardiogram (ECG) monitoring. The echocardiographic examination showed normal-sized heart chambers and the absence of valvular involvement. An agglutination test for brucellosis was found to be positive with a titer of 1/320. High fever, arthralgia, and splenomegaly regressed following doxycycline plus rifampicin therapy, but there was no improvement in the AV block. A permanent pacemaker was implanted because of the detection of an average heart rate of 48 bpm. Conclusion: Because cardiac failure and rhythm abnormalities are reported in the course of Brucella infection and may be associated with significant outcomes, cases with brucellosis should be evaluated carefully in terms of cardiac involvement. This report aims to draw attention to complete AV block as an extremely rare complication of Brucella infection.

We report the case of a 14-year-old boy patient admitted to our outpatient clinic with palpitations and documented supraventricular tachycardia. Electrophysiological study and ablation were planned. In the electrophysiological study, two tachycardias with different cycle lengths and morphologies were induced. After elimination of the slow pathway, left posterior accessory pathway was detected and successfully ablated. Another pathway was detected following that ablation. Due to the slow retrograde conduction of this pathway, diltiazem infusion was started to uncover the accessory pathway. The second accessory pathway was at the left posteroseptal region and was successfully ablated. After a 30-minute waiting period, no tachycardia was induced. In addition, no fluoroscopy was used during the procedure.

Background: Traditionally fluoroscopy has been used for navigation of catheters during electrophysiological procedures. Recent advances in electroanatomic mapping technologies resulted in a decrease and even in elimination of fluoroscopy exposure during these procedures. Methods: Electrophysiological procedures were performed with the use EnSite NavX™ or Velocity™ (St. Jude Medical, St. Paul, MN, USA) systems. Following construction of the right atrial geometry, other relevant geometries were formed (right ventricle, coronary sinus, or left atrium). Fluoroscopy was used in patients with complex congenital heart disease, in younger children, and during transseptal punctures. Cryoablation or radiofrequency was used for catheter ablation. Results: A total of 305 patients underwent catheter ablation for various supraventricular and ventricular tachyarrhythmia substrates using EnSite system guidance. No fluoroscopy was used in 191 (63%) of these cases. The mean fluoroscopy time in the rest of the procedures was 13.9 ± 11.6 minutes (0.2–60 minutes). The mean procedure time was 184 ± 71 minutes. No complications were noted except for temporary diaphragmatic paralysis in one patient and temporary AV block in another patient following cryoablation. Acute success rate in achieving complete elimination of arrhythmia substrates was 95% (290/305). The recurrence rate was (31/271) 11.4% at a mean follow-up time of 42 ± 23 months. Conclusions: Fluoroscopy can be significantly decreased or even eliminated in the majority of catheter ablation procedures. Long-term results demonstrate that this can be done efficiently and safely. (PACE 2012; 35:1067–1073)