title: Contribution of the electrophysiological and anatomical analysis of the atypical atrioventricular nodal tachycardia circuit.
abstract: OBJECTIVE
  To analyze retrograde conduction during junctional ectopic tachycardia (JET) episodes and investigate the existence of a relationship between the presence of a retrograde block and the risk of atrioventricular block (AVB) development during radiofrequency ablation procedures in patients with nodal atrioventricular tachycardia (NAVT).
  
  
  METHODS
  145 male and female patients aged 16-84 years, with NAVT who had undergone radiofrequency catheter ablation in the posteroseptal region of the right atrium were studied. Evaluation criteria were anatomical location and electrophysiological behavior of retrograde conduction during NAVT, in order to understand the nodal reentrant circuit (classifying the tachycardia as typical or atypical), and monitoring of retrograde conduction during JET episodes for risk-predicting AVB events.
  
  
  RESULTS
  Of the 145 patients studied, 132 (91%) met electrophysiological and anatomical criteria of the typical form of NAVT, and 13 (9%) of atypical form. During the ablation, 5.3% with the typical form and 30.8% of the atypical form presented risk events for AVB. After the ablation, complications were a total AVB episode in one patient and a first-degree AVB episode in another in the typical group, and one first-degree AVB in the atypical group. All three episodes were preceded by risk events and resulted in permanent nodal injury.
  
  
  CONCLUSIONS
  Patients with atypical NAVT presented higher percentages of risk events for atrioventricular block than did patients with the typical form (p=0.021).A careful observation of retrograde conduction during JET episodes is vital in order to avoid permanent damage in AV nodal conduction, such as TAVB, after the ablation procedure.
authors: Instituto Nacional de Cardiologia de Laranjeiras, Universidade Federal Fluminense e Ritmolab, Rio de Janeiro, RJ, Brazil. mailasilva@cardiol.br
authors: Maila Seifert Macedo
authors: MS
authors: Silva
authors: Roberto Luiz M da Silva
authors: RL
authors: Sá
authors: Márcio Luiz A
authors: ML
authors: Fagundes
authors: Fernando E S
authors: FE
authors: Cruz Filho
authors: Leonardo B
authors: LB
authors: Arantes
authors: Silvia
authors: S
authors: Boghossian
authors: Adriana Monteiro C David
authors: AM
authors: de Almeida
authors: Rafael Lopes
authors: RL
authors: Fagundes
authors: Luiz José
authors: LJ
authors: Romeo Filho
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017115:Catheter Ablation / Q000009:adverse effects*; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006327:Heart Block / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000209:etiology / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery