| Objective:We design and develop a new type of temperature-controlled intravascular radiofrequency ablation balloon,through the longitudinal line ablation of hypertrophic intima,to explore the impact of radiofrequency balloon angioplasty on the atherosclerosis plaques,arterial remodeling and possible mechanisms,to provide a new way for the treatment of atherosclerosis.Methods:Following balloon denudation injury of the abdominal aortas,rabbits were raised on a cholesterol diet for 12 weeks,producing atheroma in that region.Two rabbits were killed at the 12 th week,and abdominal aortas were removed for histopathological examination to confirm if atheroma was established in that region.We performed abdominal aorta angioplasty using a radiofrequency balloon and a plain balloon with the same balloon pressure and time.After angioplasty was performed,each rabbit was returned to a normal diet,animals were sacrificed at 1 hour,the 1st week,the 2nd week,the 4th week following the procedure,the abdominal aortas were explanted and processed for histopathology and immunohistochemistry examination to investigate the effect of radiofrequency balloon on the remodeling and histomorphology of atherosclerotic arteries,comparison of the two groups of lumen cross-sectional area,intima area,media area,the ratio of hypertrophic intimal and medial areas,the ratio of luminal area to the total vascular areas enclosed by the external elastic lamina,the expression of TGF-?1,MMP-2 and MMP-9 in the 1st week,the 2nd week,the 4th week.Results:(1)After balloon denudation injury of the abdominal aorta,and raised on a cholesterol diet for 12 weeks,the entire abdominal aorta was gray and white,pathology staining showed significant proliferation of arterial intima,under fibrous cap,there was a large number of inflammatory cells and foam cells,the media elastic fiber disintegration,fracture,smooth muscle cells disorder,atherosclerosis model was established successfully.(2)Compared with plain balloon,radiofrequency balloon can significantly increase the diameter of the lumen,decrease the area of intima and media,more effectively remodel the artery,the greater the power was,the more obvious the expansion of the lumen was seen.(3)In the 1st week,the 2nd week,the 4th week,radiofrequency balloon group showed localized fibrosis in the ablation site,radiofrequency-derived energy application to the vessel wall induced transmural tissue coagulation,mural wall damage was replaced by fibrotic tissue,inflammatory cells and foam cells were decreased,disappeared,media smooth muscle cells were necrosis,elastic fibrosis were stretched.(4)When the power was high,leading to circumferential transmural injury of artery,fibrotic scar tissue comprising full thickness.(5)In the 1st week,the 2nd week,the 4th week,the expression of TGF-?1,MMP-2 and MMP-9 is significantly higher in radiofrequency balloon group than plain balloon group,while there was no difference in the first hour.Conclusion:1.Compared to plain balloon,radiofrequency balloon could significantly increase the cross-section area of the lumen,an enlargement of the vessel lumen was seen due to reduction of the hypertrophic intima and media thickness,led to thinning of the artery.2.Collagen was synthesized in the radiofrequency ablation area,inflammatory cells and foam cells were reduced in intima,in the media there was also loss of nuclei seen in smooth muscle cells,the spiral structure of collagen unraveled and the fibers fused and reconjugated,increased the stability of plaque.3.Radiofrequency thermal damage induced the expression of TGF-?1,MMP-2 and MMP-9.4.High output radiofrequency energy resulted in circumferential transmural injury of artery,the smooth muscle cells were necrosis,the media showed presence of fibrotic scar tissue comprising full thickness,leading to disappearance of wall elasticity,the intima showed inflammatory cells infiltration in middle term. |
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