Experimental Study Of Pathological Change Of Venous Valves After Thrombosis

Objective: To study the pathological changes of venous valves in different time after the thrombosis of jugular vein of rabbits.Materials and methods: 1. To establish venous thrombosis model: New Zealand white rabbits were operated with the jugular veins ligatde on the right side. Thrombosis was confirmed by ultrasound one day after the ligation. 2. Experimental grouping: 25 rabbits with successful modeling were randomly divided into 5 groups. The jugular vein within thrombosis was harvested 1,3,5,7,14 days after the ligation respectively. The jugular vein of other side was also obtained in five rabbits which were slected from each group as the control group. The indicators to observe include: the samples underwent hematoxylin - eosin (HE) staining, Weigert (elastic fibers) stain and Van Gieson (collagen fibers) staining. The valve's pathological change was observed by optical microscope, and was scored according to the valve damage scale.Results: 1. 9 valves were observed in control group, while 8,7,7,7 and 5 valves were observed in 1 day,3 days,5 days, 7 days and 14 days group respectively. Valve structure could not be found in the remaining vessels. 2. The rabbit venous valves were so meager that could not be observed by the naked eye. there was no elastic fibers and smooth muscle in the valves. 3. Inflammatory cells had attached to the valve margin one day after ligation and endothelial cells showed exfoliation. Collagen fiber was proliferative, which may be broken and disordered later. Then more endothelial cells broken off, and the surface rupture occurred in the valve endothelial wall. The valves could be separated from the vessel wall seriously.Conclusion: From the initial invasion of inflammatory cells to collagen fiber proliferation and structural damage to the valves, the key time of the pathological changes is 5-7 days. The thrombus could lead to valve inflammation and collagen fiber hyperplasia mainly within 5 days. Valve would be damaged severely with the thrombus after 7 days or more times. Thus thrombolysis or removal of thrombus should be applied within 5 days in order to protect valves. The protection of the venous valves is not significant after 7 days because the basic structure of valves is damaged .After thrombolysis whether valve can repair and how the function changes are worthy of study further. However the rabbit venous valve structure is significant different from human's , so deeper studies about human's valves destroy and repair are greatly needed.