Inhibition of atrial fibrillation by pulmonary vein isolation and auricular resection—experimental study in a sheep model

OBJECTIVE: The MAZE procedure has proven effective for surgically treating atrial fibrillation, but its acceptance has been limited due to the complex dissection pattern. A new simplified operative technique, that comprises two important components of the MAZE procedure, has been evaluated in an established animal model of induced sustained atrial fibrillation. METHODS: In eight sheep, median sternotomy was performed for cardiopulmonary bypass via femoral and bicaval cannuiation. Bipolar atrial and ventricular electrodes (16) were applied for computerized EKG-sampling. Atrial fibrillation was induced during continuous theophylline infusion (0.5 mg/kg/min) by repetitive (10x) biatrial stimulation. Atrial response was monitored and mapped. The operative procedure was accomplished in induced ventricular fibrillation: Right and left atrial appendices were resected and a circumferential transmural incision around all pulmonary veins was performed and closed. After defibrillation, the atria were stimulated again using the above protocol and EKGs were sampled. RESULTS: Sustained atrial fibrillation was inducible in all animals (80 stimulation episodes, median duration 31 s, 6 incessant episodes) prior to dissection. Post resection of the atrial appendices and pulmonary vein isolation, atrial fibrillation was not inducible in any of the eight animals (80 stimulation episodes). A significant interatrial (104 +/- 13 ms) and atrioventricular (208 +/- 19 ms) conduction delay was observed post dissection. CONCLUSION: We conclude that the described procedure is effective for the inhibition of sustained atrial fibrillation in morphologically unaltered atria. The operative approach involves less dissection than the MAZE procedure, which could facilitate its use in concomitant mitral procedures. The clinical significance of the observed AV-Delay has to be evaluated.