Heike E. Schneider

Incidence of coronary artery injury immediately after catheter ablation for supraventricular tachycardias in infants and children

BACKGROUND Several case reports have documented coronary artery stenosis or even occlusion after radiofrequency energy ablation (RFA) in children and adults. Coronary involvement early and late after RFA has also been described in animal models. OBJECTIVE The purpose of this study was to assess prospectively the incidence of coronary artery injury early after catheter ablation for supraventricular tachycardias (SVT) in children. METHODS From October 2002 to January 2008, 212 consecutive patients younger than 21 years with SVT underwent selective coronary angiography before and 30 minutes after RFA or cryoablation. RESULTS Median patient age was 12 years (range 0.3-20.4 years), and median body weight was 47 kg (range 5.5-130 kg). An accessory pathway was diagnosed in 112 patients, AV nodal reentrant tachycardia (AVNRT) in 84 patients, and both an accessory pathway and AVNRT in 16 patients. Congenital heart disease was present in 31 patients. In 2 of 117 patients who had RFA for an accessory pathway, an acute reduction in luminal diameter of the coronary artery adjacent to the ablation site was observed. These two patients with a structurally normal heart showed ST-segment changes with normalization of the ECG within 1 week. Both were clinically asymptomatic, and two-dimensional echocardiography documented normal ventricular function. Noninvasive testing did not reveal any evidence of persistent myocardial ischemia. No coronary artery damage was noted after ablation for AVNRT or after ablation with cryoenergy. CONCLUSION Coronary artery narrowing adjacent to the RFA site was noted in 2 of 117 patients with an accessory pathway and occurred only in patients with a posteroseptal pathway. Coronary angiography could be helpful in avoiding coronary lesions in these settings.

Left cardiac sympathetic denervation for the management of life-threatening ventricular tachyarrhythmias in young patients with catecholaminergic polymorphic ventricular tachycardia and long QT syndrome

BackgroundLeft cardiac sympathetic denervation (LCSD) may be a therapeutic adjunct for young patients with catecholaminergic polymorphic ventricular tachycardia (CPVT) and long QT syndrome (LQTS) who are not fully protected by beta-blockade.ObjectiveThe objective of this analysis was to report our institutional experience with LSCD in young patients for the management of life-threatening ventricular arrhythmias in CPVT and LQTS.MethodsTen young patients with CPVT and LQTS underwent transaxillary LSCD at our institution. Mean age at surgery was 14.0 (range 3.9–42) years, mean body weight was 45.7 (range 15.5–90) kg. Five patients had the clinical diagnosis of CPVT, three were genotype positive for a mutation in the ryanodine-receptor-2-gene. Four of five LQTS patients were genotype positive. Indications for LCSD were recurrent syncope, symptomatic episodes of ventricular tachycardias and/or internal cardioverter–defibrillator (ICD) discharges, and aborted cardiac arrest despite high doses of beta-blockers.ResultsLCSD was performed via the transaxillary approach. No significant complications were observed. Two patients already had an ICD, 6 patients received an ICD at the same operation or shortly thereafter. Median length of follow-up after LCSD was 2.3 (range 0.6–3.9) years. After LCSD a marked reduction in arrhythmia burden and cardiac events was observed in all patients while medication was continued. None of the patients had any further ICD discharge for sustained VT.ConclusionsAfter LCSD, arrhythmia burden could significantly be reduced in all our young patients with CPVT and LQTS.

Catheter ablation of idiopathic left and right ventricular tachycardias in the pediatric population using noncontact mapping

BACKGROUND Idiopathic ventricular tachycardia (VT) in children with a structurally normal heart can cause significant morbidity, and although rare, mortality. Conventional activation and pace mapping may be limited by nonsustained tachycardia or unstable hemodynamics. OBJECTIVE The aim of this study was to assess feasibility of catheter ablation of idiopathic VT in the pediatric population guided by noncontact mapping. METHODS Twenty consecutive pediatric patients with idiopathic VT underwent electrophysiologic study with the intention to use the noncontact mapping system EnSite 3000 (EnSite Array, St. Jude Medical Inc., Minneapolis, Minnesota). The multielectrode balloon array was introduced into the left or right ventricle, respectively, and tachycardia was analyzed using color-coded isopotential maps as well as reconstructed unipolar electrograms on the virtual geometry. The region of origin was identified in all of them, and the site of earliest activation with a QS pattern of the unipolar electrograms was guided for sites of ablation. RESULTS Idiopathic VT originated from the right ventricular outflow tract in 6 patients, from the left ventricle in 8, and from the aortic sinus cusp in 6 in this cohort with a median age of 14.4 (range: 4.8 to 20.9) years. Ablation was attempted in 18 of 20 children, and was acutely successful in 17 of these 18 (94%). During a mean follow-up of 2.3 +/- 1.7 years, VT recurred in 3, 2 of them have been treated with a second procedure, resulting in an overall intermediate-term success in 16 of 18 (89%) children with idiopathic VT. CONCLUSION Noncontact mapping can safely and effectively be used to map and guide catheter ablation of the tachycardia substrate of idiopathic VT in pediatric patients.

Clinical, echocardiographic and histopathologic findings in nine patients with surgically explanted ASD/PFO devices: Do we know enough about the healing process in humans?

BACKGROUND Atrial septal defects (ASD) and persistent foramen ovale (PFO) are managed in increasing numbers by catheter interventions as an attractive alternative to surgery. Early complications have been described in clinical series whereas late complications are rare. No series are reported with clinical, echocardiographic and histological data. METHODS AND RESULTS We collected clinical, echocardiographic, and histolological data of nine patients with surgically explanted devices. Occlusion devices were explanted after a mean interval of 3.4 ± 2.4 years (range 0.9-8.3). Indications were recurrent thromboembolic events in five, residual shunt/dislocation in three, and growing mass on echocardiography despite oral anticoagulation in one patient. Two patients suffered potentially live threatening events due to coronary embolism. One of them had to be resuscitated due to ventricular fibrillation. Histologically, residues of superficial thrombus formation could be demonstrated in two of the devices. In another patient, hyperplastic tissue formation was related to a local inflammatory process but not to a thrombus as suspected by echocardiography. CONCLUSION Late complications after device implantation may occur up to 8 years after device implantation and may be potentially live threatening. Echocardiographic controls should be prolonged beyond the first year after implantation and every explanted device should be histologically worked up in an experienced center. Up to now, the mechanisms of late thrombogenesis are not fully understood.

Melody transcatheter valve: Histopathology and clinical implications of nine explanted devices

OBJECTIVES We examined interventionally implanted valved Melody conduits after surgical explantation by means of histology and immunohistochemistry and matched these findings with clinical data in order to assess in vivo biocompatibility and to identify risk factors for graft failure. METHODS 9 Melody valves had been implanted in 8 patients (pulmonary n = 7, tricuspid position n = 1). Indication for explantation included significant obstruction in 7 patients and valve insufficiency in 1 patient. 4 of 8 patients had suffered from endocarditis. Mean interval between implantation and explantation was 3.2 (1.8-5.2) years. All explants were worked up using a uniform protocol with fixation in formalin and embedding in methylmethacrylate. RESULTS All but one valve of the explanted Melody grafts were thin and histologically intact without any pathological findings. Complete neo-endothelialization could be demonstrated by means of immunohistochemistry. All 4 Melody valves from patients with endocarditis showed dense granulocytic infiltrations, 3 of these showed thrombotic material within the valves. CONCLUSION This report covers the first series of explanted Melody valves from humans applying a uniform protocol for histopathological examination. Good biocompatibility of the Melody valves could be demonstrated after a mid-term follow-up. Factors for graft failure included endocarditis, outgrowth, and residual stenosis. These findings may have significant implications for the implant procedure as well as care of the patients during long-term follow-up.

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

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).

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. 

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.

Transbaffle catheter ablation of atrial re-entrant tachycardia within the pulmonary venous atrium in adult patients with congenital heart disease

AIMS Catheter ablation of atrial re-entrant tachycardia in patients after atrial switch procedure for transposition of the great arteries or with a Fontan circulation is technically challenging if the critical part of the re-entry circuit is located within the pulmonary venous atrium (PVA). We report our experience in transbaffle access (TBA) to the PVA for ablation of atrial re-entrant tachycardia focusing on technical details. METHODS AND RESULTS In eight patients, six after Mustard procedure and two with a Fontan circulation, endocardial mapping of atrial re-entrant tachycardia revealed the critical part of the re-entry circuit within the PVA. A total of 10 ablation procedures were performed. Detailed angiographic assessment of the anatomy of the systemic and pulmonary venous atria was performed prior to baffle puncture. Transbaffle access was successfully established with a standard transseptal needle in 9 of 10 procedures. No major complications occurred. At the end of the procedure and the removal of the transseptal sheath, there was no residual shunt in any patient. CONCLUSION Transbaffle access to the PVA for ablation of atrial re-entrant tachycardia is feasible, less invasive than alternative approaches and can be safely applied in patients after Mustard procedure or with a Fontan circulation. However, the rigidity of prosthetic material may preclude baffle puncture at least in a subset of those patients.

Slow pathway ablation in a 5-year-old boy with atrioventricular septal defect: value of cryoenergy application.

Thomas Kriebel, MD ()) Heike Schneider, MD · Matthias Sigler, MD Thomas Paul, MD Department of Pediatric Cardiology and Intensive Care Medicine University Hospital Georg-August-University Göttingen Robert-Koch-Straße 40 37075 Göttingen, Germany Tel.: +49-551/396203 Fax: +49-551/392561 E-Mail: tkriebe@gwdg.de Sirs: In patients with a complete atrioventricular septal defect (AVSD) the compact AV node occupies a low position adjacent to where the posterior rim of the atrial septum contacts the posterior rim of the ventricular septum anterior to the mouth of the coronary sinus [11]. From here, the common bundle extends along the lower rim of the ventricular septal defect, resulting in a posterior course for the intraventricular conduction network [7]. Therefore, in patients with tachycardias based on septally located substrates like atrioventricular nodal reentrant tachycardia (AVNRT) and atrial flutter, radiofrequency catheter ablation is associated with a high risk of complete AV-block. Cryoenergy with its specific features cryoadherence and cryomapping may therefore be of value in this setting. Successful radiofrequency ablation of atrial flutter, atrial reentrant tachycardia and supraventricular tachycardia based on a right anteroseptal accessory pathway has occasionally been reported in patients with an AVSD [8, 9, 12]. To the best of our knowledge, this is the first report of a successful slow pathway cryoablation in a patient with an AVSD.