RESUMO
A suction electrode catheter was used for low energy, partial ablation of the atrioventricular (AV) node junction in 12 dogs. In 10 dogs, partial injury of the AV node was induced. In six dogs, delivered energy was measured precisely with use of a specially designed electronic circuit. The total energy required for partial ablation was 225 +/- 91 J. The increase in PR (p less than 0.0001) and AH (p less than 0.001) intervals was proportional to the energy delivered. After ablation, the PR interval increased from 98 +/- 10 to 154 +/- 33 ms (p less than 0.004) and the AH interval from 59 +/- 8 to 102 +/- 16 ms (p less than 0.004). There was no significant change in QRS, QTc, HV or RR intervals. AH and PR intervals were significantly prolonged at 3, 7 and 14 days after ablation (p less than 0.05). Anterograde conduction was significantly altered in 10 dogs. Anterograde AV node effective refractory period increased from 157 +/- 14 to 214 +/- 45 ms (p less than 0.005). Anterograde AV node Wenckebach cycle length increased from 196 +/- 30 to 244 +/- 44 ms (p less than 0.002). Retrograde conduction was assessed in three dogs. Retrograde AV node effective refractory period increased from 156 +/- 21 to 260 ms in two dogs, with complete retrograde block in the third. These changes persisted for up to 2 weeks. Pathologic changes were limited to the region of the AV node. In four dogs adherent thrombus without pulmonary emboli was noted. Partial focal injury to the AV node is feasible in the canine model.(ABSTRACT TRUNCATED AT 250 WORDS)
