摘要
目的采用数值模拟方法研究人工心脏辅助装置植入对左心室内血流动力学的影响。方法首先利用心血管集中参数模型获取了健康状态、心衰状态以及人工心脏泵辅助状态下收缩末期左心室三维几何模型,其中选取超弹性材料Ogden为心肌材料,以左心房压力,主动脉压力以及通过左心室容积计算获取的左心室壁面位移作为边界条件,利用CFD方法对上述三种情况进行左心室的数值模拟。同时对比了健康时的模拟结果和生理状态下的左心室压力,以及心衰和人工心脏泵辅助两种状态下的血流动力学指标的差别。通过左心室压力和流速等评价灌注和负荷的情况,通过壁面切应力和涡流,评价人工心脏泵辅助后的左心室血流动力学变化规律。结果健康状态下模拟的左心室压力与生理指标相符合。在心衰和人工心脏泵辅助状态下,收缩期内左心室压力与健康状态比分别降低了1718 Pa和8455 Pa,辅助后左心室最大压力下降速度高于心衰时。人工心脏泵辅助后,舒张期壁面切应力峰值由4.3 Pa降低至3.8 Pa,收缩期壁面切应力峰值由4.1 Pa降低至1.3 Pa,射血速度峰值由1.61 m/s降低至0.68 m/s,主动脉瓣开放时间由0.25 s增加至0.65 s,左室射血分数由43.6%增加至52.7%,心室底端漩涡持续时间由0.35 s增加至0.51 s,顶端漩涡出现血流分离。结论左心室压力对比表明本研究方法可以用来模拟左心室的行为。人工心脏泵辅助能够快速降低心室内压力和心室负荷,增加灌注时间,提高器官灌注,降低左心室壁面切应力以及提高左心室内血液流场的涡流强度,延长涡流持续时间。
Objective This work focused on the hemodynamic（ velocity,pressure,wall shear stress, vortex）effect of artificial heart blood pump on the left ventricle by the means of numerical simulation. Methods The left atrial pressure,aortic pressure and the left ventricular volume of the 3 situations（ healthy,heart failure,assisted）were derived from the lumped parameter cardiovascular model,which was used as the boundary conditions. Then we used the volume data to build 3D geometry models of the 3 situations at end-systole phase. In the work,the hyper-elastic material Ogden was chosen to stand for myocardium. We carried out the numerical simulation by the means of computational fluid dynamics（ CFD ）,compared the left ventricular pressure （ LVP）in simulation and physiology,and the hemodynamic index between the heart failure（HF）and artificial heart blood pump assisted situations. The LVP and the velocity were used to evaluate the perfusion and ventricular unloading,while the wall shear stress（ WSS）and vortex were used to evaluate the flow pattern. Results The LVP of the simulation and the physiology in healthy situation were the same. The pressure dropped 1788 Pa and 1455 Pa respectively in heart failure and assisted situations during the systole and the pressure drop speed was much higher in assisted situation. The peak WSS were 4. 3 Pa and 3. 8 Pa during diastole,4. 1 Pa and 1. 3 Pa during systole in HF and assisted situations. The peak velocities were 1. 61 m / s and 0. 68 m / s in HF and assisted situations during systole,yet the duration of ejecting were 0. 25 s and 0. 65 s. As a result, the left ventricular ejection fraction（LVEF）increased from 43. 6% to 52. 7%. The existence duration of lower vortex increased from 0. 35 s to 0. 51 s in HF and assisted situations,and the blood separated from the upper vortex in assisted situation. Conclusions The LVP in simulation and physiology were the same,demonstrating the simulation method available. The artificial heart blood pump assisted can help to decrease the LVP and the ventricular load,extend the ejecting duration and improve perfusion. What’s more,it can reduce the WSS, enhance the vortex and extend the duration of vortex existence.
出处
《北京生物医学工程》
2015年第4期331-339,共9页
Beijing Biomedical Engineering
基金
国家自然科学基金(11272022
1122001
1372014)
北京工业大学基础研究基金(015000514312002)
北京工业大学京华基金(015000543114506)资助
关键词
心力衰竭
人工心脏泵辅助
计算流体力学
血流动力学
heart failure
artificial heart blood pump assisted
computational fluid dynamics
hemodynamics
