Objective：To study the influence of ablated cardiac fat pad on atrial fibrillation induced by a single extra-stimulus in dogs. Methods： Twenty-two dogs were anesthetized and their chest cavity was openned through a median sternotomy （2 dogs died of fibrillation immediately after opening） to expose the 3 cardiac fat pads： the medial superior vena cava and aortic root fat pad （SVC-Ao FP）, the right pulmonary vein-atrial junction fat pad （RPV FP）, and the inferior vena cava-left atrial junction fat pad （IVC-LA fat pad）. The atrial effective refractory period （AERP）, dispersion of AERP （dAERP）, and pulmonary vein effective refractory period（PVERP）were measured under baseline and after ablation of the 3 fat pads. The left superior pulmonary veins were stimulated by SiSlbursting stimulation and S1 S2 program stimulation to induce atrial fibrillation before and after ablation. Results： After ablation, AERP increased from （137＋16） ms to （147±16） ms and PVERP increased from （131±14） ms to （141±9） ms,while dAERP decreased from （17.0±4. 6） ms to （12.0±4. 3） ms （P〈0.05）. After ablation, SISa cycle length decreased from （ 173 ± 25） ms to （ 145 ±21） ms when used for restimulation after ablation（ P〈0. 05 ）. S1S2 could not induce AF again. Conclusion： Ablation of the 3 cardiac fat pad can influence the electrical remodeling of the atrial and the pulmonary vein,which may hamper the induction of atrial fibrillation.[著者文摘]