[Ablation of AV nodal tachycardia: new aspects on mechanism and therapy].

Dual AV nodal pathways are the substrate for the occurrence and induction of AV nodal reentry tachycardias (AVNRT). Characteristics of fast or slow pathway conduction are amenable to selective ablation by radiofrequency energy. Thus, the substrate of AVNRT is eliminated with preservation of antegrade AV nodal conduction. Radiofrequency catheter ablation is a highly effective and safe modality of treatment with success rates ranging from 80 to 100%. The risk of inadvertently inducing complete heart block is substantially lower with slow when compared to fast pathway ablation. Thus, selective ablation of slow pathway conduction has been recently advocated as the procedure of choice. When regarding to concomitant atrial fibrillation or flutter, ablation of slow pathway conduction might be preferable given the resulting higher antegrade Wenckebach cycle lengths after slow pathway ablation.