球囊配置对冠状动脉支架扩张和回弹行为的影响

Effect of Balloon Configuration on Coronary Stent Expansion and Recoil

探讨不同球囊配置对冠状动脉支架扩张和回弹行为的影响,以期从球囊配置的角度为球囊-支架系统的有限元模拟策略及优化设计提供一定的指导。采用Solid Works建立Cypher支架模型及4种Raptor球囊模型(无褶、三褶、六褶和六褶锥形末端球囊模型),使用Hypermesh软件进行各模型的网格划分,应用Abaqus Explicit模块完成不同球囊-支架系统的扩张和回弹模拟。结合制造商提供的压力-直径顺应性曲线验证模拟结果的合理性,并引入"狗骨头"率、轴向缩短率及径向回弹率等3个参数评估不同球囊-支架系统模拟效果的优劣。结果表明,无褶球囊-支架系统在较低压力下扩张明显,各项参数较其他球囊-支架系统很大;六褶球囊-支架系统相较三褶在扩张中的压力-直径顺应性曲线更接近制造商提供的数据,且轴向缩短率(6.1%)和径向回弹率(1.9%)也均优于三褶;六褶锥形末端球囊-支架系统由于与导管间的连接使得"狗骨头"率(12.0%)和轴向缩短率(3.85%)明显降低。对于球囊-支架系统的有限元模拟,在支架的初级设计阶段可以采用理想的无褶球囊模型进行支架的扩张模拟,但考虑支架的瞬态行为和最终定位时,球囊的褶皱和锥形末端设计等几何特征不可忽略;在球囊-支架系统的优化设计中,球囊褶数可以从三褶调整为六褶,更有益于支架的均匀扩张。

The expansion and recoil of coronary stents under different balloon configurations were simulated to provide scientific guidance for the finite element simulation and optimization design of balloon expandable stents. The Cypher stent and four Raptor balloons（ non-folded,tri-folded,six-folded and six-folded balloon with conical tip） were modeled by Solid Works,the mesh generation was finished by Hypermesh,and the expansion and recoil of different balloon expandable stents were simulated by Abaqus Explicit. The simulation results were verified by the pressure-diameter compliance curve of the manufacturer. Besides,the maximum ＂ dog-boning＂,foreshortening and radial recoil rates were depicted to evaluate different simulation effect. The non-folded balloon expandable stent expanded larger than others with low stress,and all three coefficients were the highest. Six-folded balloon expandable stent behaved well,its pressure-diameter compliance curve perfectly agreed with the manufacturer’s data than tri-folded configuration. Furthermore,its foreshortening（ 6. 1%） and recoil（ 1. 9%） rates were also lower than the former. As for the last one,its ＂ dog-boning ＂（ 12%） and foreshortening（ 3. 85%） rates were significantly lowest which may due to the conical tip. In the early stage of stent design,the non-folded configuration can be used to carry out the expansion and recoil simulation of the stent,but considering the transient behavior and the final positioning,the folded level and the conical tip design should be included in the simulation. From the point of optimization design,six-folded configuration ismore beneficial to the uniform expansion of the stent than the tri-folded model.