Percutaneous catheter cryothermal ablation of atrioventricular nodal reentrant tachycardia: efficacy and safety of a new ablation technique.

BACKGROUND: Radiofrequency catheter ablation is nowadays a widely used technique for the treatment of arrhythmias; however, due to the possible complications such as atrioventricular block when radiofrequency is delivered in the septal area, this type of energy is not optimal. In contrast, cryoenergy has several positive features; first of all, it allows for the creation of reversible lesions and hence to test the effects of the ablation while the lesion is still forming thus reducing the number of ineffective and useless lesions. In addition, it also allows for the evaluation of the acute effects on the structures adjacent to the ablation site. The aim of the present study was to analyze the effectiveness and safety of catheter cryoablation in the treatment of atrioventricular nodal reentrant tachycardia (AVNRT). METHODS: Thirty-two patients presenting with AVNRT underwent catheter cryoablation using a 7F catheter. When the optimal parameters were recorded, "ice mapping" at -30 degrees C was performed for 80 s to validate the ablation site by means of a reversible lesion. If the expected result was achieved, the cryoablation was carried out lowering the temperature to -75 degrees C for 4 min thus creating a permanent lesion. RESULTS: Slow pathway ablation guided by a slow pathway potential was successfully performed in 31 out of the 32 patients with a mean of 2.6 +/- 1.0 cryoapplications. No complications occurred in any patients. Transient AH prolongation was observed in 2 patients in a midseptal site during the ice mapping phase of AVNRT ablation. CONCLUSIONS: Cryoablation is a safe and effective technique for AVNRT ablation. It may be useful particularly when the ablation must be performed close to the atrioventricular node or His bundle, due to the possibility of validating the site of ablation by means of ice mapping that creates only a reversible lesion.