Cardiac fulguration, a new alternative therapy for atrioventricular nodal reentrant tachycardia.

Ten patients underwent endocardial catheter ablation of the atrioventricular junction for atrioventricular nodal reentrant tachycardias. Unipolar cathodic discharges at the distal electrode were administered against an external plate. Bipolar His and atrial deflections showed a mean of 0.15 mv and 0.5 mv respectively. Mean total energy used per patient was 195 J (range: 50-750), with a mean number of ablating discharges of 2.0 per patient, (range: 1-5). Complete atrioventricular block was achieved, but conduction reappeared in all except one patient, after a mean interval of 19.9 min. Electrophysiological evaluation was assessed 3-8 days after ablation. Sustained atrioventricular nodal reentrant tachycardias were no longer inducible in any patient. Retrograde conduction was abolished in six, and was slow and decremental in four. First-degree atrioventricular block, with intranodal delay was diagnosed in six, with an AH interval that ranged from 240 to 130 ms. Mean cycle length for appearance of Wenckebach atrioventricular block was 390 ms after ablation. One patient developed complete atrioventricular block after two discharges of 50 J, another required a repeat ablation for recurrence of intranodal tachycardia and also developed complete anterograde block in a new session of ablation with a 150 J discharge. In these two patients permanent pacing was needed. Eight patients were cured after a mean follow-up of 20 months. Less energy and fewer discharges should be administered to abolish functional dissociation of the atrioventricular node, without complete interruption of anterograde conduction.