快速起搏犬心房48h后左房组织学的逆重构

Reversal structural remodeling on left atrium after rapid atrial pacing 48 hours in dogs

目的探讨阵发性心房颤动(简称房颤)的左房组织学重构在转复窦性心律后能否逆转及其过程。方法健康成年杂种犬24只,随机分为四组,每组6只。A组快速起搏48h;B组假手术组,观察48h;C组快速起搏48h后,继续观察24h;D组假手术组,观察72h。分别于术前、起搏48h、停止起搏后6,12,18,24h行超声心动图检测心室收缩末期左房左右径(LATD)、上下径(LASID)、前后径(LAAPD)。A、B组于实验开始后48h,C、D组于72h,取左房组织,电镜观察心房肌超微结构的改变;HE染色观察心房组织结构;Masson染色观察心肌纤维化程度。结果起搏48h后A、C组LATD、LASID、LAAPD与同时点B、D组及术前比较增大(P<0.05)。快速起搏右房48h后,心肌细胞溶解、线粒体增大等超微结构改变明显,糖原增多;心肌间质内胶原沉积增加;恢复窦性心律后LATD、LASID、LAAPD有缩小趋势,18h后与对照组相比无差异(P>0.05);超微结构的改变部分恢复正常;纤维化程度减轻。结论犬阵发性房颤转复并维持窦性心律后24h,组织学重构不能完全逆转。

Objective To examine the reversibility of the changes in structural remodeling on left atrium in dogs with rapid atrial pacing. Methods Twenty four adult mongel dogs were randomly divided into 4 groups. Group A ：48 hours atrail taehypacing group（ n = 6） ;Group B：sham operated with 48 hours monitoring （n = 6） ;Group C：reversing 24 hours after 48 hours atrail tachypacing group （ n = 6） ; Group D ： sham operated with 72 hours monitoring （ n = 6）. Two-dimensional echocardiography was performed to assess the changes of left atrial dimension at 0 h,48 h, 54 h,60 h,66 h, 72 h. The changes of the left atrial tissular uhrastructure were observed by electron microscope and light microscope. Atrial fibrosis was detected by Masson staining. Results Compared with group B and pre-operation,left atrial dimension increased with fibrosis and myolysis in group A. In group C ,the enlarged left atrial dimension showed a tendency to decrease afer pacing stop. Ultrastructural abnormalities were partially reversed 24 hours after AF reversion. The fibrosis observed by Masson staining remained weakly positive in sinus rhythm after AF. Conclusions Structural remodeling can be partially reversed in 24 hours after AF converted to sinus rhythm.