PATHOLOGICAL FINDINGS FOLLOWING SLOW PATHWAY ABLATION FOR AV NODAL REENTRANT TACHYCARDIA

Introduction: AV nodal reentrant tachycardia is routinely cured using radiofrequency catheter ablation techniques, However, there remains co ntroversy as to whether the reentrant circuit for this tachycardia exi sts solely in the AV node or whether perinodal atrial tissues are vita l to the circuit, In addition, the effects of radiofrequency ablation of the slow pathway of AV nodal reentrant tachycardia on the AV node a re not known, We examined an autopsy specimen to determine the anatomi cal location and extent of AV nodal damage of radiofrequency slow path way ablation for cure of AV nodal reentrant tachycardia. Methods and R esults: A 64-year-old woman with confirmed AV nodal reentrant tachycar dia underwent a successful ''slow pathway'' AV modification with a sin gle radiofrequency application. Five months after the procedure, the p atient died from a spontaneous intracranial hemorrhage. Postmortem gro ss pathological examination of the heart was performed, The heart was then sectioned and stained for histologic examination, On gross examin ation, a pale lesion 0.5 cm in diameter was seen on the endocardial su rface adjacent to the tricuspid annulus, approximately 0.85 cm anterio r to the coronary sinus os and 1.15 cm from the apex of the triangle o f Koch where the AV node resides, Histologic examination revealed a ri ght atrial lesion composed of connective tissue and fat, The compact A V node and surrounding transitional cells were unaffected histological ly, with normal atrial cells lying between the AV node and the lesion. Conclusion: Ablation of the slow pathway to cure AV nodal reentrant t achycardia does not produce any gross or histologic damage to the AV n ode, suggesting that the AV nodal reentrant circuit does not exist in its entirety in the AV node.