犬急性心房颤动电重构现象的实验研究

目的 观察短阵心房颤动(房颤)的电重构现象及其恢复过程，探讨电重构与房颤再发及维持的关系。方法 15只健康成年犬于左、右心房外膜7个部位缝合双极记录电极，自心耳给予600次／min起搏诱发2h房颤，其中5只犬每间隔10min测量左、右心耳的心房有效不应期(AERP)，观察其恢复过程；另10只犬在房颤前后分别测量在起搏周长350ms、250ms、200ms时7个部位的AERP并记录电生理检查时房颤的诱发率及其持续时间。结果 2h房颤后心房各点AERP显著缩短，对心率适应不良，AERP离散度增高，继发性房颤诱发率增高、持续时间延长。AERP缩短可持续30min，60-80min后恢复。左心耳AERP恢复过程慢于右心耳。可诱发房颤的部位AERP更短，与继发性房颤的平均持续时间呈显著性负相关。可诱发房颤的心房其AERP离散度明显增高，但与继发性房颤的持续时间无关。AERP心率适应不良部位继发性房颤的诱发率高于生理性AERP心率适应性部位。低位右心房及左心耳部位的期前兴奋易于诱发房颤。结论 2h诱发的房颤足以使健康心房发生类似持续性房颤的电重构，电重构使房颤易于再发。AERP离散度与房颤的诱发有关，AERP缩短与房颤的持续性有关，房性早搏的发生部位与房颤的易患性有关。

Experimental research of electrical remodelling of acute atrial fibrillation in dogs

Objective To observe electrophysiological changes of both atria induced by 2 h atrial fibrillation (AF)and their relationship with inducibility and maintenance of induced AF. Methods Seven bipolar recording elec-trode were sutured to 7 sites of both atria of 15 healthy mature mongrel dogs. AF was induced by rapid atrial pacing (600 bpm)for 2 hours. In 5 dogs, the atrial effective refractory period (AERP)was measured at atrial appendages of both sides for every 10 minutes after secession of AF to observe the recovery course of the shortened AERP. In the other 10 dogs, AERP was measured at 7 epicardial sites of both atria under different pacing cycle length (350 ms,250 ms,200 ms)2 hours before and after AF was induced and ceased. Simultaneously, the inducibility and duration of induced AF were also assessed during the electrophysiological study. Results After the induced sustained 2 hours AF, AERP at the 7 sites were significantly shortened, dispersion of AERP was increased significantly, maladapta-tion of AERP existed, and inducibility and duration of induced AF increased significantly too. Furthermore, the sta-ble shortening of AERP persisted for at least 30 minutes and recovered to baseline within 60 - 80 minutes. The recov-ery course of shortened AERP was slower at left atrium than that at right one. Shortness of AERP had significant cor-relation with inducibility and duration of the induced AF, however, dispersion of AERP only correlated with the in-ducibility of the induced AF. The inducibility of AF was higher at the sites revealed maladaptation of AERP to the heart rate (HR)than sites without such physiological adaptation to HR. The premature beats from lower right atrium and left atrial appendage showed higher inducibility of AF. Conclusions Induced AF just for 2 h could induce elec-trical remodelling on normai atrium. Dispersion of AERP is determinant factor of the inducibility of AF, however, shortening of AERP (shortening of wave length)is a determinant factor of the AF duration. The origin of the atrial premature beats might also determine the inducibility of AF.