冠脉重叠支架虚拟置入的有限元分析

Finite Element Analysis of Virtual Implantation of Coronary Overlapped Stent

在经皮冠状动脉介入治疗(PCI)中,重叠支架多运用于治疗弥漫长病变冠脉。关于重叠支架的临床研究有很多,虽提供手术效果和支架的临床疗效,但不能直观地揭示重叠支架置入过程中支架与支架、支架与血管之间的相互作用。通过对重叠支架置入弥漫长病变冠脉进行有限元分析,观察支架置入过程中支架与血管形态和应力的改变,并对其进行分析。通过计算机断层扫描血管造影(CTA),重建出真实的右冠状动脉(RCA)弥漫长病变模型。应用有限元方法,对重叠Resolute药物洗脱支架(DES)置入冠脉长病变过程进行模拟,重叠长度3 mm,整个过程包括支架的压握与输送、远端支架与近端支架的置入。在支架虚拟置入过程中,通过观察支架与血管形态和应力的变化进行支架与支架、支架与血管间相互作用的分析。支架置入后,管腔截面积由最初的1.4 mm^2增加到6.5 mm^2,血管狭窄得到很好的治疗。在支架重叠区域,位于外层的远端支架由于过度扩张,其应力大于近端支架的应力。管壁在支架重叠处的应力(0.64～0.81 MPa)大于非重叠区域的应力(0.32～0.56 MPa),重叠处的血管过度扩张使得管腔截面积没有受到重叠支架的影响。研究表明,重叠支架可使血管血流得以通畅,但支架重叠区域支架与血管的受力较大。

In the percutaneous coronary intervention（PCI）, overlapping stents are often used to treat diffuse coronary lesions. There are many clinical studies on overlapping stents, which provide the clinical effect and efficacy of the stents. However, the interactions between stents and stents, stents and blood vessels have not been demonstrated by direct observations. The aim of this study was to investigate the changes of stent, vessel morphology and stress during stenting by analyzing the coronary stents with superimposed stents. A real diffuse lesion model of right coronary artery（RCA） was reconstructed by computed tomography angiography（CTA）. The finite element method was used to simulate long-term implantation of overlapping resolute drug-eluting stent（DES）. The overlap length was 3 mm. The entire procedure included the grasping and delivery of the stent, the placement of the distal stent and the proximal stent. During the virtual placement of the scaffold, the interaction between the stent and the stent, the stent and the blood vessel was analyzed by observing the changes of the stent and the vascular morphology and stress. The lumen cross-sectional area increased from the initial 1.4 mm^2 to 6.5 mm^2 after stenting, and the stenosis of blood vessels was well treated. In the stent overlap area, the distal stent located in the outer layer was more stressed than the proximal stent due to over-expansion. The stress of tube wall at overlap（0.64～0.81 MPa） was larger than that of non-overlap region（0.32-0.56 MPa）. Over-dilatation of blood vessels in the overlap caused the lumen cross-sectional area not to be influenced by overlapping stent. The study shows that overlapping stents can make blood vessels unobstructed; and there were greater stress in the overlapping parts between the stent and vessel.