David Backhoff

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.

Radiofrequency Catheter Ablation of Atrial Tachycardias in Congenital Heart Disease: Results With Special Reference to Complexity of Underlying Anatomy

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

Formation of multiple conduit aneurysms following Matrix P® conduit implantation in a boy with tetralogy of Fallot and pulmonary atresia

We report on a 6-year old boy with tetralogy of Fallot and pulmonary atresia in whom a 16 m Matrix P conduit was implanted between the pulmonary artery and the right ventricle at the age of 16 months. Five years later he developed severe stenosis of the distal conduit anastomosis. The notable findings were several aneurysms of the conduit proximal to the distal stenosis within the high-pressure region. The wall of the aneurysms contained xenogeneic conduit tissue without inflammatory or foreign-body response. We believe that aneurysm formation of the conduit was a result of fatigue of the conduit wall under suprasystemic pressure.

Severe Constrictive Pericarditis After Parvovirus B19 and Human Herpes Virus 6 Infection in a 9-Year-Old Girl

We report on a 9-year-old girl who developed signs of congestive heart failure with significant ascites due to constrictive pericarditis. Cardiac catheterization was performed to establish the diagnosis and to rule out restrictive cardiomyopathy. Endomyocardial biopsies were positive for activated macrophages and small-vessel disease, but no viral genomes were detected. Open pericardectomy was performed and histopathologic examination of the resected thickened pericardium showed extensive fibrosis and hyaline degeneration. A combined infection with parvovirus B19 (PVB19) and human herpes virus 6 (HHV6; subtype B) was proven within the resected pericardium. We suggest that local HHV6-induced immunosuppression enhanced the PVB19 infection, thus resulting in chronic infection and leading to constrictive pericarditis.

Transvenous and non-transvenous implantable cardioverter-defibrillators in children, adolescents, and adults with congenital heart disease: who is at risk for appropriate and inappropriate shocks?

Aims Non-transvenous implantable cardioverter-defibrillators (ICDs) as used in small patients and in patients with congenital heart disease (CHD) have not been compared with transvenous systems with respect to safety and efficacy yet. Aim of the present study was to describe the prevalence of and to identify contributing factors for appropriate and inappropriate ICD discharges in patients with non-transvenous and transvenous ICD. Methods and results Single centre analysis of all paediatric and CHD patients who had received an ICD since 1995. One hundred and ninety-five patients were included. A transvenous system had been implanted in 153 (78%) subjects, the remaining 42 (22%) individuals received an extracardiac (EC)-ICD system. During mean follow-up of 4.5 years appropriate ICD shocks were noted in 32 (16%) individuals, whereas inappropriate shocks occurred in 22 (11%) patients. Appropriate shocks were more frequent in patients with an EC-ICD than in individuals with transvenous systems (29% vs. 13%, P = 0.02). Rapidly conducted atrial tachycardia (AT) was the most common reason for inappropriate shocks (76%). Rate of inappropriate shocks was not different between EC and transvenous systems (12% vs. 11%, P = 0.26). Lead failure was more prevalent in subjects with an EC-ICD (29% vs. 7%, P = 0.001). Conclusion Individuals with EC-ICD systems were particularly prone to experience appropriate shocks. As rapidly conducted AT was the most common reason for inappropriate ICD shocks, rigorous treatment of these arrhythmias and proper ICD programming are mandatory. Though lead failure was of concern in EC-ICD patients, EC-ICD systems were not inferior with respect to inappropriate shocks.