Role of canine epicardial fat pads in maintaining atrial fibrillation / 第二军医大学学报

ABSTRACT

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.