Open-heart endocardial radiofrequency ablation: An alternative to incisions in maze surgery

Background. Radiofrequency (RF) ablation produces transmural atrial lesions in vitro and may provide advantages over incisions currently used in maze surgery. This study examines the feasibility, safety, and efficacy of open- heart endocardial RF ablation. Methods. Eighteen sheep (42.8 +/- 4.4 kg, age < 2 years) underwent left tho racotomy with placement of pacing leads on a pulmonary vein and the left at rial dome. On cardiopulmonary bypass, lesions were made using incision and suture or a novel RF ablation device in three sites: PVC = circle excluding pulmonary veins, IAB = line across the interatrial bundle, SVC = line from the superior to the inferior vena cava. Pacing across the PVC lesion was a ttempted to assess the completeness of each lesion. Preselected animals (in cision n = 4, RF n = 5) were recovered and pacing attempts were repeated at 1 month. After sacrifice, hearts were sectioned and measured for lesion si ze and completeness. Results. RF ablation lesions took less time to create (total bypass time: R F 51.8 min vs incision 106 min, P < 0.001). No evidence of thromboembolism, atrial rupture, or coronary sinus thrombosis was seen. All PVC lesions wer e complete as demonstrated by the inability to pace across them. Stained se ctions demonstrated that acutely studied incision lesions were thinner than RF lesions; however, all lesions were transmural and similar in width at 1 month. Conclusions. RF ablation consistently created transmural lesions more quick ly than the incision and suture method and without additional complications . Endocardial RF ablation appears to be a simple and effective alternative to surgical incisions during open-heart atrial Maze procedures. (C) 2001 Ac ademic Press.