ENDOCAVITARY ATRIOVENTRICULAR ABLATION OF NODAL REENTRANT TACHYCARDIAS

Atrioventricular nodal reentrant tachycardias which, for a long time, could only be treated medically, may now benefit from catheter ablatio n. The rapid retrograde pathway was an effective initial target but ca rried a risk of complete atrioventricular block of about 10%. Nowadays , most operators deliver the radiofrequency energy (endocavitary caute ry) to the slow nodal pathway. Different techniques of guidance (anato mical, electrophysiological, rapid potential, slow potential) are asso ciated with high success rates: 90 to 100%. However, experimental stud ies suggest that the slow potentials arise from transitional cells wit hin the tachycardia circuit (the anatomical substrate of the slow path way) There is still a risk of complete atrioventricular block (1 to 5% ) which should be clearly explained to patients referred for ablation of this constantly benign arrhythmia.