INRIA Paris-Rocquencourt, Le Chesnay Cedex, France; UPMC Univ Paris 6, Laboratoire Jacques-Louis Lions, Paris, France.
J Surg Res. 2014 Jan;186(1):44-55. doi: 10.1016/j.jss.2013.07.037. Epub 2013 Aug 11.
Computational fluid dynamics has been increasingly used in congenital heart surgery to simulate pathophysiological blood flow, investigate surgical options, or design medical devices. Several commercial and research computational or numerical codes have been developed. They present different approaches to numerically solve the blood flow equations, raising the question whether these numerical codes are equally reliable to achieve accurate simulation results. Accordingly, we sought to examine the influence of numerical code selection in several complex congenital cardiac operations.
The main steps of blood flow simulations are detailed (geometrical mesh, boundary conditions, and solver numerical methods) for congenital cardiac operations of increasing complexity. The first case tests different numerical solutions against an analytical, or exact, solution. In the second case, the three-dimensional domain is a patient-specific superior cavopulmonary anastomosis. As an analytical solution does not exist in such a complex geometry, different numerical solutions are compared. Finally, a realistic case of a systemic-to-pulmonary shunt is presented with both geometrically and physiologically challenging conditions. For all, solutions from a commercially available code and an open-source research code are compared.
In the first case, as the mesh or solver numerical method is refined, the simulation results for both codes converged to the analytical solution. In the second example, velocity differences between the two codes are greater when the resolution of the mesh were lower and less refined. The third case with realistic anatomy reveals that the pulsatile complex flow is very similar for both codes.
The precise setup of the numerical cases has more influence on the results than the choice of numerical codes. The need for detailed construction of the numerical model that requires high computational cost depends on the precision needed to answer the biomedical question at hand and should be assessed for each problem on a combination of clinically relevant patient-specific geometry and physiological conditions.
计算流体动力学已越来越多地应用于先天性心脏病手术中，以模拟生理血流，研究手术方案或设计医疗设备。已经开发了几种商业和研究计算或数值代码。它们采用不同的方法来数值求解血流方程，这就提出了一个问题，即这些数值代码是否同样可靠，以获得准确的模拟结果。因此，我们试图在几种复杂的先天性心脏手术中检验数值代码选择的影响。
详细介绍了血流模拟的主要步骤（几何网格，边界条件和求解器数值方法），这些步骤适用于越来越复杂的先天性心脏手术。第一个案例针对解析或精确解测试了不同数值解的影响。在第二个案例中，三维域是患者特有的上腔静脉-肺动脉吻合术。由于这种复杂的几何形状不存在解析解，因此比较了不同的数值解。最后，提出了一种具有几何和生理挑战性的全身-肺分流的现实病例。对于所有情况，都比较了商业上可用的代码和开源研究代码的解决方案。
在第一个案例中，随着网格或求解器数值方法的细化，两个代码的模拟结果都收敛到了解析解。在第二个示例中，当网格的分辨率较低且不精细时，两个代码之间的速度差异较大。具有现实解剖结构的第三个案例表明，两个代码的脉动复杂流非常相似。
数值案例的精确设置对结果的影响大于数值代码的选择。需要详细构建数值模型，这需要很高的计算成本，具体取决于回答手头生物医学问题的精度要求，并应根据临床相关的特定患者几何形状和生理条件的组合来评估每个问题。
