兔非人工通气主动脉瓣上缩窄 松解模型的建立及评价

目的 探讨在非人工通气的条件下通过升主动脉缩窄的方法建立兔主动脉瓣上缩窄—松解模型的可行性并进行评价。方法 在非人工通气的条件下，对实验兔行胸骨正中切开手术，在主动脉瓣上部分结扎升主动脉，使其内径减少约50%，则血管的横截面积减少约75%。假手术组仅开胸，不行升主动脉部分结扎。在缩窄组中，随机选取部分实验兔分别在缩窄术后8周和16周行升主动脉缩窄解除术，术后通过超声心动图、血流动力学、组织病理及透射电镜检查观察左心室结构和功能变化及心肌的组织学表现。结果 研究发现，压力超负荷可以引起左心室显著肥大。升主动脉缩窄8周的实验兔在去压力超负荷后，左心室的结构和功能完全恢复，而缩窄16周的实验兔则表现为部分恢复，表明左心室肥大的转归程度与压力超负荷的时间有关。结论 在非人工通气的条件下，采用升主动脉缩窄的方法可成功建立稳定的兔主动脉瓣上缩窄—松解模型，该模型避免了气管插管及机械通气的损伤和并发症，操作简单、效果明显、重复性好。

A rabbit model to study regression of ventricular hypertrophy

Objective To develop and characterise an animal model of left ventricular hypertrophy (LVH) regression following pressure-induced myocardial hypertrophy in rabbits without endotracheal intubation. Methods Without endotracheal intubation and mechanical ventilation, a median sternotomy that was made exactly along the midline of the sternum was performed. Ascending aortic diameter was reduced 50% above the aortic valve, which lead to an approximate 75% reduction in crosssectional area. The sham-operated rabbits underwent the same procedures without actual ligation of the aorta. The animals of early debanding group and late debanding group were subjected to the second operation for removing the ligation 8 weeks or 16 weeks after the initial banding surgery, respectively. Echocardiography, haemodynamic assessment, histology, and electron microscopy were used to assess functional and structural aspects of myocardial hypertrophy at each time point. Results The pressure overload resulted in robust LVH assessed by echocardiography, haemodynamic assessment, histology, and electron microscopy. Ascending aortic debanding completely or partially reversed LVH. The degree of LVH regression was association with the duration of pressure overload, proved by the fact that restoration of LV structure and function was complete in animals subjected to 8 weeks of aortic banding but incomplete in animals subjected to 16 weeks of aortic banding. The animals did not experience severe mechanical ventilatory impairment. Conclusion These results demonstrate an efficient and reproducible method of promoting LVH regression in rabbits without endotracheal intubation and mechanical ventilation.