A Comparison of the Pathologically Transmural and Electrical Isolation of Atrial Tissues after Once and Three Times of Bipolar Radiofrequency Ablation

A finite element model was developed to simulate the ablation results. The optimal parameters (30 w, 15 s) were obtained by changing the input energy (20 w, 25 w, 30 w, 35 w, 40 w) with different operating times (15 s, 20 s, 25 s, 30 s). Then, in vitro and in vivo experiments were performed based on the results from FEM simulation. In the in vitro experiments, 240 pieces of strips of tissues were equally divided into group A and group B, and group A was ablated once by bipolar RFA system while group B was ablated three times. After stained with Mason trichrome, the tissue was examined under the microscope to validate whether a pathologically transmural ablation was successfully achieved. In the in vivo experiments, 20 pigs were equally divided into group C and group D. Left pulmonary veins in Group C and left atrial appendages ablated once while the right pulmonary veins and atrial appendage were ablated three times, and left atrial were ablated once while their right atrial ablated three times in group D. The electrophysiological mapping was utilized to validate the electro physiologically transmural lesion. And after fed for 4 weeks, the second electrophysiological mapping was utilized to confirm the long-term electrical isolation. Pathologically transmural lesion was achieved in 51.67% and 98.33% of the atrial tissue in Group A and B respectively. Total immediate electrical isolation rate was 61.67% for once ablation, while it was 100% for three times of ablation. And the total long-term electrical isolation rate was 31.67% for once ablation, while it was 85% for three times of ablation. The results demonstrate that the three times of ablation can improve the rate of pathologically transmural and electrical isolation significantly.