不稳定斑块血管内超声特征的实验研究

目的　明确不稳定斑块的血管内超声 (IVUS)影像学特点。方法　 2 7只雄性新西兰纯种兔随机分成A组 (17只 )与B组 (10只 ) ,A组用球囊损伤腹主动脉 高脂喂养 10周 ,B组仅给予高脂喂养 10周。于 8周末将A组在腹主动脉斑块形成处转染携带人野生型 p5 3基因的重组腺病毒载体 ,于 10周末 ,两组实验兔分别给予中国斑点蝰蛇毒和组胺药物触发斑块破裂。应用IVUS分别测量、比较斑块破裂前的腹主动脉同一血管段中多个病变部位及其参考部位的IVUS指标 ,明确不稳定斑块的IVUS影像学特点。结果　破裂与未破裂斑块的参考部位的血管外弹力膜面积 (EEMA)、管腔面积、斑块面积及管腔面积狭窄率相比 ,差异无显著性意义 (P >0 .0 5 )。与未破裂斑块相比较 ,破裂斑块具有较大的偏心性 (P <0 .0 0 1) ,EEMA、斑块面积及管腔面积狭窄率明显大于前者 ,差异有显著性意义 (均P <0 .0 0 1)。破裂斑块呈现明显的正性重构 ,而稳定斑块主要表现为负性重构。结论　IVUS应用于已建立的动脉粥样硬化不稳定斑块动物模型上 ,能够准确地识别动脉粥样硬化不稳定斑块 ,本研究为临床早期发现不稳定斑块并预测斑块破裂奠定了实验基础。

Experimental study on intravascular ultrasonic features of unstable atherosclerotic plaques

Objective To identify the characteristic features of unstable atherosclerotic plaques with intravascular ultrasound (IVUS).Methods Twenty-seven New Zealand White rabbits were randomly divided into two groups: group A( n =17) and group B( n =10).Rabbits in group A underwent balloon-induced abdominal aortic wall injury and were fed on a diet of 1% cholesterol for 10 weeks.Rabbits in group B were fed on a diet of 1% cholesterol only.At the end of the eighth week,the aortic segments rich in plaques were then incubated transluminally with recombinant adenovirus carrying a p53 transgene in group A.After two weeks,IVUS was used to measure the external elastic membrane area(EEMA),lumen area,plaque area and lumen area narrowing rate at both the lesion and the reference segments in the same vessel,respectively,and lumen eccentricity index and remodeling index were calculated.Then all the rabbits in the two groups underwent pharmacological triggering with Chinese Russell's viper venom(CRVV) and histamine to induce plaque rupture and thrombosis.The characteristic features of unstable atherosclerotic plaques were derived by comparing the results of IVUS in the ruptured and non-ruptured plaques.Results There was no significant difference in EEMA,lumen area,plaque area and lumen area narrowing rate at the reference segments between ruptured and non-ruptured groups ( P > 0.05 ).However,there were more eccentric plaques in ruptured than in non-ruptured groups ( P < 0.001 ) and EEMA,lumen area,plaque area and lumen area narrowing rate in the ruptured plaques were larger than those of non-ruptured plaques ( P < 0.001 ,respectively).Positive remodeling pattern was observed in ruptured plaques while non-ruptured plaques showed negative remodeling.Conclusions IVUS can detect unstable atherosclerotic plaques and predict plaques disruption in early stage of atherosclerosis using our animal models of unstable atherosclerotic plaques.