HISTOPATHOLOGICAL STUDY FOLLOWING CATHETER GUIDED RADIOFREQUENCY CURRENT ABLATION OF THE SLOW PATHWAY IN A PATIENT WITH ATRIOVENTRICULAR NODAL REENTRANT TACHYCARDIA

The present study examined histological changes induced by catheter gu ided radiofrequency current in a patient with AV nodal reentrant tachy cardia who underwent cardiac transplantation 1 week after ablation of the slow pathway. During the electrophysiology study AV nodal conducti on curves were discontinuous and AV nodal reentry was induced. At the conclusion of the procedure there was no evidence of slow pathway func tion. Histological sections from the explanted heart demonstrated a sh arply demarcated atrial lesion (15 x 5 x 4 mm) extending from the sept al portion of the tricuspid annulus to the posterior border of the AV node. The lesion did not encompass the compact AV node. These observat ions support the hypothesis that the slow pathway is comprised of atri al approaches to the AV node and is distinct from the compact AV node.