心房颤动对肺静脉肌袖结构影响的研究

目的：探讨心房颤动（atrial fibrillation，AF）时肺静脉肌袖结构的变化及其意义。方法：健康杂种犬17只，随机分为心房颤动组（11只）和对照组（6只），应用快速心房起搏建立慢性房颤动物模型，通过HE染色、Masson 染色研究犬右上肺静脉的结构变化。结果：与对照犬相比，AF犬肺静脉肌袖内心肌细胞增大、排列紊乱；细胞核大小不甚规则，核异型性明显，细胞内可见肌纤维断裂；心肌纤维之间连接组织积聚，使心肌细胞之间的间隔增宽。从左心房到肺静脉方向，心肌袖组织逐渐变薄，末端肌束被纤维组织隔离。心肌袖内可见肌纤维方向突然改变，心肌细胞在长轴切片上显示为横断面，而在短轴切片上显示为纵切面。AF犬肺静脉肌袖内胶原组织较对照犬明显增多，排列紊乱，分布不均匀，围绕单个心肌细胞的胶原纤维网减少或断裂。结论：肺静脉肌袖结构的特殊性及其结构重构可能是形成肺静脉局部微折返的组织学基础，是AF发生和维持的重要机制。

Structural changes of myocardium sleeves in canine pulmonary veins due to sustained atrial fibrillation

Objective: To study structure changes of myocardium sleeves in canine pulmonary veins(PVs) due to sustained atrial fibrillation(AF). Methods: The tissue and cell structure in individual veins was assessed by light microscopy using HE and Masson′s Trichrome staining. Results: Compared with control dogs, sections from AF dogs showed cellular hypertrophy, disarranged cell bundles and increasing connective tissue. Some myocytes were surrounded by collagen tissue and myofilament was disrupted. Masson′s Trichrome stain showed that from the left atrium towards the vein, and the myocardial sleeves were gradually attenuated and ended in a rounded tip surrounded by fibrous tissue. Within myocardial sleeves, sharp transitions in fiber orientation were sometimes observed. It was apparent that myocytes on the endocardial side of myocardial sleeves were cut transversely in longitudinal sections. Samples from AF dogs showed, however, collagen tissue increased markedly and disrupted some areas. Conclusion: The special structure of the myocardial sleeve in PVs and its structural remodeling due to sustained AF may provide a substrate for forming micro re entry, which is an important mechanism for the occurrence and maintenance of AF.