持续快速心房起搏对犬肺静脉肌袖组织结构的影响

探讨持续快速心房起搏对犬肺静脉肌袖组织结构的影响。 1 4条杂种犬 ,其中起搏犬 8只 ,对照犬 6只。起搏犬以 40 0次 /分的频率持续起搏右心房 9～ 1 0周 ,对照犬仅放置起搏导线及起搏器 ,但不起搏。 9～ 1 0周后对所有犬均进行心房颤动 (简称房颤 )的诱发 ,并取其肺静脉组织进行HE染色、Masson′s染色和电镜检查。结果 :终止起搏后起搏犬的持续房颤 ( >1 5min)诱发率为 87.5 % ( 7/8) ,显著高于对照犬 ( 0 % ,P <0 .0 1 )。起搏犬肺静脉肌袖组织的光镜特征为心肌细胞变性 ,胶原组织大量增生 ;电镜下变性心肌细胞的超微结构异常主要累及线粒体和肌原纤维。对照犬肺静脉肌袖组织的形态学未见明显病理改变。结论 :持续快速心房起搏可导致犬的肺静脉肌袖组织发生显著的形态学重构 ,后者可能与该模型房颤的机制有关。

Effect of Chronic Rapid Atrial Pacing on the Tissue Structure of Myocardial Sleeves in Canine Pulmonary Veins

The purpose of this study was to investigate the effect of chronic rapid atrial pacing on the structural morphology of pulmonary veins (PVs) in a canine model of sustained atrial fibrillation (AF). Fourteen mongrel dogs were divided into rapid atrial pacing group (8 dogs) and control group (6 dogs). After pacing electrode and pacemaker were implanted, rapid atrial pacing in 400 bpm was performed only in atrial pacing dogs. After 9 10 weeks, inducibility of sustained AF and tissue structure of PVs were studied in all dogs. The research methodology of tissue structure included hematoxylin eosin (HE) staining, Masson's trichrome staining and electron microscopy. Results: Inducibility of sustained AF in rapid atrial pacing group was significantly higher than that in control group (87.5% vs 0%, P <0.01). The major histological characteristics of PVs included degeneration of myocardial cells and hyperplasia of collagen tissues. The ultrastructural abnormalities of mitochondria and myofibrilla can be seen in the degenerated myocytes under electron microscopy. Conclusion: Chronic rapid atrial pacing can result in structural remodeling of PVs in canine. Structural remodeling of PVs may be involved in the mechanism of AF in this canine model of AF.