title: [Atrioventricular junction ablation: therapy of refractory atrial tachyarrhythmia].
abstract: OBJECTIVE
  To assess the safety and efficacy of radiofrequency atrio-ventricular junctional ablation.
  
  
  METHODS
  Consecutive group of patients with refractory atrial tachyarrhythmias in whom catheter ablation of the atrio-ventricular junction was performed.
  
  
  METHODS
  Cardiology Department at University Hospital.
  
  
  METHODS
  Atrio-ventricular junctional ablation was performed in 13 patients with a mean age of 53 +/- 13 years. Among six patients there was no evidence of organic heart disease, two had operated congenital heart disease, two had hypertensive heart disease, one had rheumatic heart disease with a prosthetic valve and the other had ischemic heart disease. The indication for ablation was drug-refractory atrial tachyarrhythmia in all patients: atrial fibrillation with uncontrolled rate in eight patients, atrial flutter in three, atrial tachycardia in one and inappropriate sinus tachycardia in one. An average of 3.7 +/- 0.9 anti-arrhythmia drugs was previously ineffective or associated with significant side-effects. Radiofrequency energy was applied between the distal pole of the ablation catheter and an indifferent cutaneous electrode with intensity of 40-65 volts for 30-60 secs. The ablation was initially performed utilizing the classical technique with the ablation catheter across the tricuspid valve. In the case of failure, an alternative method was used, with the ablation catheter positioned in the left ventricular septum. After the procedure a VVI-R permanent pacemaker was inserted in all patients.
  
  
  RESULTS
  Atrio-ventricular junctional ablation was successful in all patients after an average of 4.4 +/- 3.7 radiofrequency applications. The classical technique was successful in 11 patients (85%). The average amplitude of the His bundle electrogram recorded in the successful sites was not significantly different from the average maximum amplitude at unsuccessful sites (0.1 +/- 0.05 mV vs. 0.17 +/- 0.12 mV). There were no complications related to the procedures. During a mean follow-up of 7 +/- 4 months there was functional and symptomatic improvement in all patients. The only significant complication was an episode of sustained ventricular tachycardia that occurred three months after the ablation in a patient with Tetralogy of Fallot.
  
  
  CONCLUSIONS
  In patients with refractory atrial tachyarrhythmias, atrio-ventricular junctional ablation is a safe and effective therapeutic option. The alternative technique should be reserved for cases of unsuccessful ablation with the classic method. Due to its potential significant side-effects, this therapy should be a last alternative option.
authors.affiliation: Serviço de Cardiologia, Hospital de Santa Maria, Lisboa.
authors.forename: J
authors.initials: J
authors.lastname: Sousa
authors.forename: L
authors.initials: L
authors.lastname: Brandão
authors.forename: M C
authors.initials: MC
authors.lastname: Barreiros
authors.forename: M C
authors.initials: MC
authors.lastname: Vagueiro
mesh_terms: D000328:Adult; D000368:Aged; D001283:Atrioventricular Node / Q000601:surgery*; D002036:Bundle of His / Q000601:surgery*; D017115:Catheter Ablation; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D013610:Tachycardia / Q000503:physiopathology / Q000601:surgery*
vernacular_title: Ablação da junção aurículo-ventricular: Terapêutica de recurso de taquiarritmias auriculares refractárias.