药物洗脱支架置入弯曲冠状动脉血管后药物浓度场及壁面切应力分布

摘要 背景：血管闭塞性疾病主要治疗方法之一，支架置入的后期再狭窄问题开始制约支架的进一步发展。 目的：分析药物洗脱支架置入弯曲冠脉血管后的药物浓度场及壁面切应力分布规律，为临床应用及药物洗脱支架的进一步完善提供理论指导。 方法：选取3种药物释放率情况，采用数值方法对药物洗脱支架置入弯曲冠脉后的药物浓度场和壁面切应力情况进行分析。 结果与结论：血管的弯曲和支架的置入对药物扩散的浓度场有较大影响。药物释放速率的改变对浓度分布规律没有影响。由于流场分布的不均匀，弯曲冠脉血管内侧的药物浓度高于外侧，下游的浓度高于上游。外侧支架附近的血管壁上出现低切应力区，加上低的药物浓度分布，使得这些位置(特别是上游区域)成为再狭窄萌发的高危险区。结果提示，如果根据置入支架所处位置的流场分布特点，有意识的对支架表面载药量的分配分布进行合理的优化，适当增加上游和外侧药物涂层的浓度，减少下游和内侧涂层的浓度；增加径向连接筋的载药量，减少连接筋数目，充分利用流动带来的上游药物浓度,使得血管壁附近的药物浓度分布更加均匀合理，这将既节省药量，又有利于抑制内膜增生。 关键词：药物洗脱支架；冠状动脉；药物浓度分布；内膜增生；心血管置入物 doi:10.3969/j.issn.1673-8225.2010.42.016

Drug concentration and wall shear stress distribution in curved coronary artery with drug-eluting stents

Abstract BACKGROUND: The post-implantation restenosis of stent, which is one of the main treatments of vascular occlusive disease, has restricted the further development of drug eluting stent. OBJECTIVE: To clarify the distribution law of drug concentration and wall shear stress distribution after drug-eluting stent was embedded in a curved coronary artery, so as to prefect the clinical application of drug eluting stent theoretically. METHODS: The drug concentration and wall shear stress were numerically investigated at three different diffusion rates after drug-eluting stent was embedded in a curved coronary artery. RESULTS AND CONCLUSION: The artery twisting and stent placement had great impact on the drug diffusion concentration field, while no influence on the change of drug diffusion rate. The asymmetric flow pattern resulted in higher drug concentrations along the inner artery and downstream artery compared with the outer and upstream arteries, respectively. The low wall shear stress and drug concentration on artery wall near the outer stent made these locations (especially the upstream region) the high-risk areas to induce restenosis. Results indicated that drug distribution on stent surface could be optimized according to the flow pattern. Drug coating may be increased on outer wall and upstream while decreased on inner wall and downstream to make full use of the drug moving downstream, and reduce the radial links while increase the drug dose. Therefore the drug distribution near artery wall could be more rationale. In that case it not only can reduce drug doses but also can be helpful to control intimal hyperplasia.