犬心外膜脂肪垫在持续性心房颤动中的作用

目的 探讨心外膜重要结构心外膜脂肪垫在持续性心房颤动(房颤)维持中的作用及机制.方法 22只健康杂种犬,随机分为2组:12只犬通过心外膜快速起搏8周建立持续性房颤模型(A组),10只犬为假手术组(B组).分别刺激右前脂肪垫、下腔静脉-心房下部脂肪垫、左房背侧脂肪垫,采用心外膜标测技术比较刺激前后标测部位房颤周长变化.消融下腔静脉-心房下部脂肪垫后再次诱发房颤,重复刺激右前脂肪垫并记录刺激前后房颤周长变化.取A组和B组犬脂肪垫标本做组织学检查.结果 右侧入路诱发持续性房颤后,刺激右前脂肪垫,发现右上肺静脉、右下肺静脉和右肺静脉前庭房颤周长缩短(P＜0.05),右房顶与左房顶房颤周长无明显变化;刺激下腔静脉-心房下部脂肪垫,发现右上肺静脉、右下肺静脉和右肺静脉前庭房颤周长缩短(P＜0.05),右房顶与左房顶房颤周长无明显变化.左侧入路诱发持续性房颤后,刺激左房背侧脂肪垫,发现左上肺静脉、左下肺静脉和左肺静脉前庭房颤周长缩短(P＜0.05),左房顶与右房顶房颤周长无明显变化.下腔静脉-心房下部脂肪垫消融后,重复诱发房颤,刺激右前脂肪垫时右上肺静脉、右肺静脉前庭房颤周长缩短(P＜0.05),右下肺静脉房颤周长无变化.结论 持续性房颤犬右前脂肪垫、下腔静脉-心房下部脂肪垫和左房背侧脂肪垫3个脂肪垫通过诱发同侧肺静脉及其前庭快速激动来参与房颤的维持.在持续性房颤时右前脂肪垫主要影响右上肺静脉的房颤周长,并通过下腔静脉-心房下部脂肪垫来影响右下肺静脉;下腔静脉-心房下部脂肪垫对于右下肺静脉的影响要大于右上肺静脉.

Role of canine epicardial fat pads in maintaining atrial fibrillation

Objective To investigate the effects of epicardial fat pads on the maintenance of persistent atrial fibrillation and its mechanism. Methods Twenty-two healthy mongrel dogs were randomly divided into experimental group (n=12) and control group (n=10). Persistent atrial fibrillation was induced with eight-week rapid atrial pacing in the experimental group (Group A), and 10 dogs in the control group underwent sham operation. The changes of atrial fibrillation cycle length were measured before and after stimulation of the right anterior fat pad, inferior vena cava-inferior atrial fat pad and left atrial dorsal fat pad. After ablation of the inferior vena cava-inferior atrial fat pad, atrial fibrillation was induced again. The changes of atrial fibrillation cycle length were measured again before and after restimulation of the right anterior fat pad. The fat pads were dissected for histological evaluation. Results After atrial fibrillation was induced through the right approach, the right anterior fat pad was stimulated, and the atrial fibrillation cycle length was significantly reduced in the right superior pulmonary vein, right inferior pulmonary vein, and right pulmonary vein atrium (P<0.05), but there was no significant change in atrial fibrillation cycle length at the atrial roofs. After stimulating the inferior vena cava-inferior atrial fat pad, atrial fibrillation cycle length was significantly reduced in the right superior pulmonary vein, right inferior pulmonary vein and right pulmonary vein atrium (P<0.05), while there were no significant changes at the atrial roofs. After atrial fibrillation was induced through the left approach, the atrial fibrillation cycle length was significantly reduced in the left superior pulmonary vein, left inferior pulmonary vein and left pulmonary vein antrum after stimulation of the left atrial dorsal fat pad (P<0.05), but there were no significant changes at the atrial roofs. After ablation of the inferior vena cava-inferior atrial fat pad, atrial fibrillation was induced again; after stimulation of the right anterior fat pad, the atrial fibrillation cycle length was significantly reduced in the right superior pulmonary vein and right pulmonary vein antrum (P<0.05), but there were no significant changes in the right inferior pulmonary vein. Conclusion Three epicardial fat pads (the right anterior fat pad, inferior vena cava-inferior atrial fat pad and left atrial dorsal fat pad) in dogs maintain the atrial fibrillation through triggering rapid firing in the ipsilateral pulmonary vein and atrium during atrial fibrillation. During persistent atrial fibrillation, the right anterior fat pad mainly affect the atrial fibrillation cycle length in the right superior pulmonary vein and the right inferior pulmonary vein by exciting the inferior vena cava-inferior atrial fat pad. The inferior vena cava-inferior atrial fat pad has a greater influence on the atrial fibrillation cycle length in the right inferior pulmonary vein than that in the right superior pulmonary vein.