Elektrophysiologische Untersuchung und Katheterablation

Background

In the last 20 years, significant progress could be achieved in the diagnosis and therapy of tachyarrhythmias in children and adolescents. Electrophysiological study and catheter ablation of supraventriuclar tachycardia have proved to be extremely effective and safe procedures. Therefore, this therapy can be offered today as first-line therapy to families with symptomatic older children and adolescents.

Aim of article

This report briefly illustrates symptoms and natural course of paroxysmal supraventricular tachycardia in the young. Subsequently, principles of electrophysiological study and catheter ablation including the results as achieved so far in children are presented. Typical clinical situations are discussed according to the current guidelines of the German Society for Pediatric Cardiology. Finally, for pediatric patients with asymptomatic ventricular preexcitation current guidelines are discussed.     

Dual Atrioventricular Nodal Non-Reentrant Tachycardia in a Child Undergoing Repair of Ventricular Septal Defect

Paroxysmal non-reentrant supraventricular tachycardia due to double ventricular response through antegrade dual atrioventricular nodal pathways by a single atrial excitation has been reported in limited adult cases but not in pediatric patients with structurally normal hearts or with congenital heart defects. We report the case of a 5-year-old boy with non-reentrant double-ventricular response (DVR) supraventricular tachycardia (SVT) after repair of ventricular septal defect. To the best of our knowledge, this is the first pediatric report about an electrophysiologic study and successful selective radiofrequency (RF) catheter ablation for the slow pathway leading to tachyarrhythmia that is difficult to manage medically. In conclusion, non-reentrant DVR SVT is a rare form of tachycardia that should be considered in the differential diagnosis of SVT in children after repair of congenital heart diseases. It is amenable to mapping and RF catheter ablation.     

The results of electrophysiological study and radio-frequency catheter ablation in pediatric patients with tachyarrhythmia

A total of 135 consecutive pediatric patients (pts) with tachyarrhythmia ranging from two to 21 years of age (median age 11 years) underwent electrophysiological study (EPS) between January 1994 and July 2001. Tachycardia could not be induced in 38 of 135 pts (28%) and studies in these patients were accepted as the normal EPS. Supraventricular tachyarrhythmia mechanisms were atrioventricular (AV) accessory pathways in 47 patients (manifest accessory pathways in 23 patients, concealed accessory pathways in 17 patients, permanent junctional reciprocating tachycardia in 7 patients), re-entry without accessory pathway in 26 patients (AV nodal reentry tachycardia in 20 patients, atrial flutter in 5 patients, sinus node re-entry tachycardia in 1 patient) and atrial ectopic tachycardia in eight patients. The diagnosis of ventricular tachycardia (VT) was made in 16 patients. Seventy-three of the 97 patients with the diagnosis of tachyarrhythmia as a result of EPS underwent radiofrequency (RF) catheter ablation. The indications, early results, complications, safety and efficacy of RF catheter ablation were reviewed in these patients. Among the 73 patients who underwent RF ablation (85 procedures), the overall final success rate for all the diagnoses was 82% (60 of 73 patients). The median follow-up period for all patients was 16 months (range 2 to 60 months). Total recurrence rate in 73 patients was 4% (3 patients). Re-ablation was performed in only one of them and was successful. Procedure-related complications occurred in eight patients (11%): transient third-degree AV block in one patient, transient second-degree AV block in one patient, atrial flutter in two patients (1 needed direct current cardioversion), and atrial fibrillation in three patients (2 needed defibrillation and transient pacemaker implantation). In one patient with permanent third-degree AV block a transvenous pacemaker implantation was required. These midterm results suggest that RF catheter ablation has a good success rate and a low complication rate in pediatric patients, especially when it is carried out in experienced pediatric cardiology centers.     

Radiofrequency Ablation in the Sinus of Valsalva for Ventricular Arrhythmia in Pediatric Patients

The need to perform catheter ablation of ventricular arrhythmia from within the sinuses of Valsalva in a pediatric patient is uncommon. This has been reported in adults, but there are little data about the feasibility, safety or efficacy of catheter ablation in the sinuses of Valsalva in the pediatric patients. This is a retrospective review of all patients aged 18 years or less, at two separate institutions with no structural heart disease that underwent an ablation procedure for ventricular arrhythmia mapped to the sinus of Valsalva from 2010 to 2015. We identified 8 total patients meeting inclusion criteria. Median age was 16 years and the median weight was 61 kg. All patients were symptomatic or had developed arrhythmia-induced ventricular dysfunction. Ablation was performed in the left sinus in 4 patients and the right sinus in 4 patients. No ablations were required in the non-coronary sinus. All 8 patients had an acutely successful ablation using radiofrequency energy. There were no complications. At a mean follow-up of 7 months (4–15 months), all patients were known to be living. Follow-up data regarding arrhythmia were available in 6 of the 8 patients, and none had recurrence of their ventricular arrhythmia off of all antiarrhythmic medications. Radiofrequency catheter ablation of ventricular arrhythmia in the sinus of Valsalva can be done safely and effectively in pediatric patients.     

Nonsymptomatic Myocardial Injury After Radiofrequency and Cryoablation: A Study of Children and Patients With Congenital Heart Disease

The aim of this study was to investigate the degree of myocardial injury following catheter radiofrequency (RF) ablation (RFA) or cryoablation and its clinical significance in children and patients with congenital heart disease. Cardiac troponin T (cTnT) or cardiac troponin I (cTnI), creatine kinase (CK), and its cardiac isoenzyme MB (CK-MB) were measured in 269 patients who underwent catheter ablation (216 RFA, 53 cryoablation) just before the procedure and again 6 hours after the end of the procedure. Follow-up studies included echocardiography and 12 lead electrocardiographics (ECGs). No clinical, ECG, nor ECG signs of ischemia were detected. Biomarkers were increased in 57.7?C75.5?%. A linear regression analysis illustrated the ablation target site and the number of RF applications as a function of higher cTnI and cTnT levels, with the maximum increase due to ventricular ablation and higher numbers of RF applications. No significant difference in cTnT levels after RFA or cryoablation were observed for AV nodal reentrant tachycardia procedures and no significant differences were observed after nonirrigated tip or irrigated tip RFA in atrial wall or ventricular wall ablation. Elevations in both troponin T and troponin I levels were commonly observed after ablation, especially in ventricular wall ablation as well as with increasing numbers of radiofrequency applications. However, unlike in patients with acute coronary syndrome, these elevated levels had no specific significance. Reference values for each ablation target site were proposed in order to potentially detect additional subclinical injuries to the coronary arteries.     

Coronary Artery Spasm During Radiofrequency Ablation of a Left Lateral Accessory Pathway

A 16-year-old female patient with Wolff-Parkinson-White syndrome and supraventricular tachycardia underwent radiofrequency (RF) catheter ablation of an accessory pathway in the left lateral area. During RF ablation she developed reversible ST segment elevation secondary to coronary artery spasm. Coronary angiography demonstrated the ablation catheter in close proximity to the circumflex coronary artery, with no evidence of coronary artery injury. Subsequently, conduction by way of the accessory pathway was successfully eliminated with cryoablation with no further coronary spasm or injury.     

Transcatheter ablation for pediatric tachyarrhythmias using radiofrequency electrical energy

Radiofrequency ablation is a promising therapeutic option for difficult tachycardias in patients of all ages. Conditions in the pediatric age group that appear most amenable to the technique include accessory pathways and ectopic focus tachycardias, but the list is likely to expand with further experience. Until all long-term risks have been better explored, our institutional policy is to restrict RF ablation to symptomatic children who have failed at least one through trial of pharmacologic control. When a choice must eventually be made between potent antiarrhythmic drugs with variable efficacy and side effects, or an involved and costly surgical procedure, transcatheter ablation would appear to be a reasonable, if not preferred, alternative.     

Pädiatrische Rhythmusstörungen

Diagnosis and therapy of cardiac dysrhythmia has become an important subspecialization in pediatric cardiology. The limited possibilities of antiarrhythmic drug therapy and antibradycardia pacing have been expanded by completely new and fascinating developments over the last 30 years. Curative treatment for the majority of tachyarrhythmias has been achieved by catheter ablation. Secondary as well as primary prevention of sudden arrhythmic death has become possible thanks to implantable defibrillators. Multiple hereditary life-threatening arrhythmia syndromes have been discovered and give a fascinating insight into the molecular genetic background of arrhythmogenesis. Cardiac resynchronization therapy has evolved into one of the few causal treatment strategies for heart failure and points toward intriguing remodeling processes at the cellular level. The following article provides practical as well as background knowledge of some of these developments.     

New Directions in Surgical Therapy of Arrhythmias

The success of the radiofrequency catheter ablation procedure for most types of supraventricular and ventricular tachycardia, particularly in young patients, largely eliminated the role of surgical therapy of arrhythmias. However, there remains a subset of arrhythmia patients in whom the catheter approach has not been successful and types of arrhythmias with high recurrence rates following initially successful catheter ablation procedures where surgery can provide more definitive therapy. In addition, the concepts of ablation therapy can be successfully incorporated into the concomitant repair of complex congenital heart disease, resulting in single-stage therapy for structural and rhythm abnormalities. Prospectively, knowledge of the role of anatomic barriers as substrates for future reentrant arrhythmia circuits provides the opportunity to alter these circuits prophylactically at the time of initial surgical repair of congenital heart disease in an attempt to avoid the late development of tachycardia. This article describes our experience during the past decade with 71 patients undergoing arrhythmia surgery using this approach.     

La tachycardie supraventriculaire chez l��enfant

Supraventricular tachycardia is the most common symptomatic arrhythmia in children. Therefore, paediatricians should be familiar with this problem. There has been great progress recently. Pathophysiological mechanisms are better known and pharmacological options more diversified. Also, curative therapy is available by catheter ablation. This article reviews this cardiac rate disorder under a number of perspectives: definition, epidemiology, categories (mainly Wolff-Parkinson-White syndrome and atrioventricular node reentry), clinical features, differential diagnosis, therapeutic options and prognosis.     

Idiopathic sustained left ventricular tachycardia in pediatric patients

BACKGROUND: Idiopathic sustained ventricular tachycardia originating from the left ventricle (ILVT) has been an indication for catheter ablation. The present study evaluated the clinical features, long-term prognosis and indications for treatment in pediatric patients with ILVT. METHODS: The subjects of the present study were eight patients (four males and four females) with a mean age at onset of 11.0 years (range 3-15 years). The mean follow-up period was 7.7 years (range 2.1-11.3 years). RESULTS: In electrophysiologic studies, intravenously administered verapamil was effective for the termination of tachycardia in all six patients who received this treatment and for the prevention of tachycardia in four of five patients. Oral administration of verapamil was effective in five of seven patients. Propranolol or flecainide was added to the treatment protocol for two patients who did not respond to verapamil alone. Tachycardia disappeared without drugs in four patients during the follow-up period and became non-sustained in another patient. Two of three patients with persistent tachycardia underwent catheter ablation. Pharmacologic treatment was very effective for ILVT among these patients. CONCLUSIONS: Pharmacologic therapy, such as with verapamil, is still the treatment of choice for ILVT because of a good long-term prognosis and potential risks and complications by manipulation of catheter ablation.     

Efficacy of percutaneous radiofrequency ablation of osteoid osteoma in children

Background Percutaneous radiofrequency (RF) ablation of osteoid osteoma has high technical and clinical success rates. However, there are limited data on its use in the treatment of osteoid osteoma in children. Objective To assess the safety and efficacy of CT-guided percutaneous RF ablation of osteoid osteoma in children and compare the outcomes with published data on its use in patients unselected for age. Materials and methods From January 2003 to July 2006, 23 children with osteoid osteoma were treated with CT-guided RF ablation using a straight rigid electrode. Their mean age was 11 years (range 3.5–16 years) and there were 15 boys and 8 girls. The procedures were carried out under general anaesthesia. Follow-up was performed to assess technical and clinical outcome. The mean follow-up period was 2.5 years (range 13–49 months). Results Technical success was achieved in 21 children (91.3%). Failure occurred in two children, in one due to failure to adequately localize the nidus within the dense sclerosis and in the other because of a short ablation time (2 min) because he developed hyperthermia. Clinical success was achieved in 18 patients within 2–5 days (primary clinical success rate 78.2%).These patients were allowed to fully weight-bear and function without limitation 1 week after the procedure. Pain recurrence was observed in two patients; one was treated successfully with a second ablation after 6 months (secondary clinical success rate 82.6%). Hyperthermia was observed in two patients during the procedure. Three other minor complications were observed: wound infection in one child and skin burn in two children. No major immediate or delayed complications were observed. Conclusion Percutaneous CT-guided RF ablation is an effective and safe minimally invasive procedure for the treatment of osteoid osteoma in children. It has high technical and clinical success rates that are slightly lower than those of patients with a wider range of ages.     

Radiofrequency ablation used for the treatment of frequently recurrent rhabdomyosarcoma in the masticator space in a 10-year-old girl

Radiofrequency (RF) ablation was performed for the treatment of recurrent rhabdomyosarcoma in a 10-year-old girl. The tumor measuring 2.4 cm in a maximum diameter was in the right masticator space and invaded the buccal mucosa at the time of third local relapse after surgical intervention, chemotherapy, radiotherapy, and photodynamic therapy. The RF electrode was placed into the center of the tumor with the computed tomography fluoroscopic guide under general anesthesia. Tumor enhancement disappeared on contrast-enhanced magnetic resonance images after RF ablation. The tumor deciduated into the oral cavity 34 days after RF ablation showing apoptosis throughout the tumor on histologic study. Buccal mucosal injury cured but she suffered from trismus. The tumor has completely disappeared for 18 months after RF ablation.     

Epicardial Ablation of Ventricular Tachycardia in a Child on Venoarterial Extracorporeal Membrane Oxygenation

Epicardial catheter ablation has been demonstrated to be safe and effective in adults, but there are limited reports in the pediatric population. We report the epicardial ablation of an incessant, hemodynamically compromising ventricular tachycardia in a 13-month-old patient on venoarterial extracorporeal membrane oxygenation. The procedure resulted in elimination of tachycardia substrate with improved cardiac size and function at follow-up. Despite a reasonable long-term outcome in this child, epicardial ablation in young patients should be reserved for similarly dire circumstances.     

Treatment with flecainide for symptomatic and refractory tachyarrhythmias in children

Nine children, aged 2.5 months to 16 years, presenting with tachyarrhythmias were treated with intravenous (i.v.) flecainide, a type 1C antiarrhythmic drug. There were four boys and five girls; seven were supraventricular and two ventricular tachycardias and three had structural cardiac abnormalities. The i.v. dose required to terminate the arrhythmias ranged from 1.0 to 2.4 mg/kg (mean 1.55 mg/kg) although a mean of 1.94 mg/kg per dose was required to maintain sustained sinus rhythm after a single i.v. dose. Eight of the patients — six supraventricular and two ventricular tachyarrhythmias, required maintenance oral flecainide. Oral dosages of 6.7–9.5 mg/kg per day (mean of 7.97 mg/kg per day in three divided doses) were required to effectively prevent the tachyarrhythmias. Intravenous and oral flecainide are safe and effective in terminating supraventricular and ventricular tachyarrhythmias. No evidence of proarrhythmia was found in the patients during follow up of between 5 and 9 months. The present limitation of performing radiofrequency ablation on infants and small children justifies the important place of medical therapy for re-entrant supraventricular tachyarrhythmias.     

Interventions in Kawasaki Disease

During the past 10 years, the clinical experience of catheter interventional treatment in Kawasaki disease has gradually increased. These treatments include balloon angioplasty, stent implantation, rotational ablation, and transluminal coronary revascularization. Because coronary artery stenosis in Kawasaki disease commonly involves severe calcification, in contrast with adult atherosclerotic coronary artery lesions, the indication or technique of catheter intervention for adult patients cannot be directly determined. Satisfactory acute results for coronary balloon angioplasty were obtained in patients in a relatively short interval from the onset of disease, especially within 6 years. However, the incidence of restenosis after angioplasty was still high. Rotational ablation may be the most appropriate catheter intervention for Kawasaki disease. The advantage of rotational ablation is the high success rate, even in patients with calcified coronary artery stenosis. Stent implantation requires larger arterial access and is not possible in younger children. Care should be paid to the detection of new aneurysm formation because this was associated with the use of additional balloon angioplasty using high-pressure balloon inflation. Anticoagulation or antiplatelet regimens are essential for long-term management.     

Radiofrequency Catheter Ablation of Supraventricular Tachycardia in Children and Adolescents

The objective of this study is to provide results and costs of catheter ablation in children and adolescents in a low-income country. Reports from first-world countries have demonstrated the cost-effectiveness of radiofrequency catheter ablation (RFCA) compared to medical treatment of supraventricular tachycardia (SVT). The study included 28 patients younger than 18 years of age with SVT in a pediatric cardiology unit in Guatemala. All patients underwent RFCA. Clinical outcome and cost-effectiveness of RFCA compared to continued medical treatment were the end points. Twenty-four patients had successful ablation (85.7%). Mean age at RFCA was 11.42 ± 3.49 years. Three patients underwent a second ablation, increasing the success rate to 96.4%. One remaining patient is awaiting a second procedure. At a mean follow-up of 13.69 ± 7.16 months, all 27 patients who had a successful ablation remained in sinus rhythm. Mean cost per procedure was 4.9 times higher than that of medical treatment. However, the estimated cost of catheter ablation equal that of medical therapy after 5.1 years and is 3.4 times less after 20 years. Radiofrequency catheter ablation of SVT in children and adolescents is safe and cost-effective compared to medical therapy. Resources must be judiciously allocated, especially in low-income countries, to treat the largest number of pediatric patients.     

Successful Cryoablation of Mahaim Tachycardia in a Child With Ebstein’s Anomaly

Mahaim fibers with decremental atrioventricular (AV) node-like conduction properties comprise less than 3 % of accessory pathways. Radiofrequency ablation of right atriofascicular pathways guided by a distinct Mahaim potential detected at the anterolateral to posterolateral tricuspid annulus or in the right ventricular free wall is a safe and highly effective treatment method. The case report presents a 16-year-old boy with Ebstein’s anomaly and symptomatic wide complex tachyarrhythmia. The electrophysiologic study and the entire ablation procedure were performed using a three-dimensional mapping system (EnSite Velocity; St. Jude Medical Inc., St. Paul, MN, USA). No fluoroscopy was used during the procedure. Electrophysiologic evaluation demonstrated typical atrioventricular nodal reentrant tachycardia and Mahaim tachycardia with a wide QRS and a left bundle branch block pattern. After Mahaim potential was located at the lateral tricuspid annulus, successful cryoablation was performed with an 8-mm-tip catheter followed by slow pathway ablation to eliminate typical atrioventricular nodal reentrant tachycardia. Cryoablation with an 8-mm-tip catheter can be an alternative treatment option for children with Mahaim tachycardia.     

Advances in pediatric electrophysiology

PURPOSE OF REVIEW: The pediatric electrophysiology literature during the past year has addressed several topics that are particularly relevant for children and other patients with congenital heart disease. This paper reviews selected studies germane to physicians and health care personnel who treat pediatric and adult congenital heart patients with arrhythmias and electrophysiologic disorders. RECENT FINDINGS: Advances in arrhythmia diagnostics have been reported in pediatrics using loop monitoring, both external and implanted. Diagnostic criteria and risk stratification strategies have been refined for the congenital and inherited rhythm disorders such as cardiomyopathies and long QT syndrome. The use of therapeutic procedures such as catheter ablation for complex arrhythmias in congenital heart disease is discussed. Finally, a summary of articles on implanted devices in pediatrics and congenital heart disease is reviewed, including implantable defibrillators, atrial antitachycardia pacemakers, and cardiac resynchronization therapy in pediatrics. SUMMARY: Pediatric electrophysiology is a rapidly changing field, with advances seen in diagnostic evaluation of arrhythmia, refinement of risk-stratification testing, and therapeutic options such as catheter ablation and cardiac rhythm management devices. The evolution of pediatric electrophysiology from a diagnostic specialty into a therapeutic and interventional subspecialty has advanced the treatment options for children with cardiac arrhythmias and conduction disorders.     

Surgical therapy of life-threatening tachycardic cardiac arrhythmias in children

Surgical techniques for tachyarrhythmias refractory to medical treatment are used with increasing frequency. Among 211 patients undergoing antiarrhythmic surgery 10 children (2 to 14 years old) were operated by electrophysiologically directed procedures. 7 patients suffered from WPW syndrome, 2 from focal atrial tachycardias and 1 from recurrent ventricular tachycardia following the repair of Fallot's tetralogy. In all cases preoperative electrophysiologic study and intraoperative mapping preceded operative ablation. Surgical treatment consisted of interruption of the bundle of Kent (3 right-sided, 2 left-sided, 3 septal), ablation of the atrial focus (1 right-sided, 1 left-sided) and right ventricular outflow tract incision. In 7 operations cryo-techniques were added. 2 children with WPW syndrome had two interventions because of tachycardia recurrences due to multiple accessory pathways. In 1 case a VVI-pacemaker was implanted postoperatively due to complete atrioventricular block. Another 2 children with prolonged postoperative bradycardia received a pacemaker prophylactically. Only the child with previous tetralogy of Fallot is still under antiarrhythmic medication while all other children are free of tachycardiac episodes. Our data confirm the efficacy of surgical treatment of tachyarrhythmias in children thereby abolishing the need for life-long antiarrhythmic medication.