The restenosis after coronary artery bypass graft(CABG) is attributed to the formation of intimal hyperplasia(IH) at the anastomosis,which is closely related to hemodynamic depend on the geometric model. In order to g...The restenosis after coronary artery bypass graft(CABG) is attributed to the formation of intimal hyperplasia(IH) at the anastomosis,which is closely related to hemodynamic depend on the geometric model. In order to give a reasonable assessment of the surgery effect and judge the long-term patency rate,the hemodynamic of CABG surgery program is compared with that of surgery design of the junction angle changed.Based on in-vivo CT coronary angiography datasets,the individual geometric model of CABG reconstructed instead of idealized geometric models are applied to simulate the real physiological blood flow utilizing pulsatile flow boundary waveforms in the present study. The simulation results show that the maximum wall shear rate(WSS) value is at the bottom of anastomosis. Moreover,the stagnation zone growing gradually with the greater angle downstream the anastomosis is prone to form the IH,which is consistent with clinical observation. It is proved that the surgery being better suited to maintain graft patency is successful.展开更多
文摘目的研究冠状动脉在不同后负荷条件下,冠脉搭桥手术后竞争流对左乳内动脉(left internal mammary artery,LIMA)血流动力学影响。方法模拟LIMA到前降支(left anterior descending,LAD)搭桥手术三维模型(three-dimensional,3D),建立与冠脉模型相对应的集中参数模型(lumped parameter model,LPM,0D),为其提供1倍和1.2倍两种不同后负荷的边界条件,同时在LAD主干处设置了25%、40%、50%、60%、75%5种不同直径狭窄程度,使用计算流体力学(computational fluid dynamics,CFD)耦合计算冠脉3D模型和0D模型,从血流动力学角度分析不同后负荷时竞争流对LIMA的影响。结果 1倍后负荷时,LAD总流量约为80 m L/min,随狭窄率增加,RC/G从2.025减小到0.280,LIMA平均血流量从26.598 m L/min增加到62.310 m L/min,震荡剪切指数(oscillatory shear index,OSI)从0.1557减小到0.0020,狭窄率小于50%时,时间平均壁面切应力(time-average wall shear stress,TAWSS)低于1 Pa;1.2倍后负荷模型中,LAD总流量为71 m L/min,随狭窄率增加,RC/G从2.222减小到0.289,LIMA平均血流量从22.188 m L/min增加到54.810 m L/min,OSI从0.1790降低到0.0024,狭窄率小于60%时TAWSS低于1 Pa。后负荷改变时,相同狭窄程度下桥血管在收缩期血流量变化很小,但舒张期流量随后负荷增大而减小。结论当冠脉后负荷较大时,竞争流强度偏大。当血管管径和狭窄程度都相同时,后负荷大的患者LIMA桥血管会因偏低的WSS和较高的OSI更容易引起"线性征",降低桥血管远期通透性。
文摘The restenosis after coronary artery bypass graft(CABG) is attributed to the formation of intimal hyperplasia(IH) at the anastomosis,which is closely related to hemodynamic depend on the geometric model. In order to give a reasonable assessment of the surgery effect and judge the long-term patency rate,the hemodynamic of CABG surgery program is compared with that of surgery design of the junction angle changed.Based on in-vivo CT coronary angiography datasets,the individual geometric model of CABG reconstructed instead of idealized geometric models are applied to simulate the real physiological blood flow utilizing pulsatile flow boundary waveforms in the present study. The simulation results show that the maximum wall shear rate(WSS) value is at the bottom of anastomosis. Moreover,the stagnation zone growing gradually with the greater angle downstream the anastomosis is prone to form the IH,which is consistent with clinical observation. It is proved that the surgery being better suited to maintain graft patency is successful.
