Department of Information Engineering, School of Electronics and Information, Northwestern Polytechnical University, Xi'an, Shaanxi, P.R.China.
Department of Cardiology, Xijing Hospital, Forth Military Medical University, Xi'an, Shaanxi, P.R. China.
Med Eng Phys. 2023 Jan;111:103942. doi: 10.1016/j.medengphy.2022.103942. Epub 2022 Dec 16.
Accurate measurement of intracoronary blood flow rate is of great significance for the diagnosis of ischemic heart disease (IHD). Computational fluid dynamic (CFD) method, combining coronary angiography images and fractional flow reserve (FFR), provides a new way to calculate the mean flow rate. However, due to the incomplete boundary conditions obtained by FFR, side branches were ignored which was likely to have a significant impact on the accuracy. In this paper, a novel CFD based method for calculating the mean intracoronary flow rate under incomplete pressure boundary conditions was proposed, in order to improve the accuracy by including the side branches.
A pressure-flow curve based flow resistance model was employed to model resistance of the epicardial arteries. A series of steady flow simulations were performed to extract the parameters of the flow resistance model, which implicitly specified constraints for splitting flow between branches and thus enabled the mean intracoronary blood flow rate to be calculated in two or more branches under incomplete pressure boundary conditions. Simulation experiments were designed to validate the proposed method in both idealized and reconstructed 3D models of coronary branches, and the impact of the assumed coefficient of the Murray's Law for splitting flow between branches was also investigated.
The mean percentage error of the proposed method was +2.05%±0.04% for idealized models and +2.24%±0.01% for reconstructed models, and it was much lower than that of the method ignoring side branches (+38.48%±10.45% for idealized models and +30.54%±6.12% for reconstructed models). When the assumed coefficient of the Murray's Law was inconsistent with the real blood flow condition, the percentage errors still maintained less than about 3.00%.
The proposed method provided an easy and accurate way to measure the mean intracoronary flow rate and would facilitate the accurate diagnosis of IHD.
准确测量冠状动脉内血流速度对于缺血性心脏病（IHD）的诊断具有重要意义。计算流体动力学（CFD）方法结合冠状动脉造影图像和血流储备分数（FFR），提供了一种新的计算平均血流速度的方法。然而，由于 FFR 获得的边界条件不完整，侧支被忽略，这可能会对准确性产生重大影响。本文提出了一种新的基于 CFD 的方法，用于计算不完全压力边界条件下的平均冠状动脉内血流速度，旨在通过包括侧支来提高准确性。
采用基于压力-流量曲线的阻力模型来模拟心外膜动脉的阻力。进行了一系列稳态流动模拟，以提取阻力模型的参数，这些参数隐含地规定了分支之间分流的限制，从而能够在不完全压力边界条件下计算两条或更多条分支内的平均冠状动脉内血流速度。设计了模拟实验来验证该方法在冠状动脉分支的理想化和重建 3D 模型中的有效性，并研究了假设的 Murray 定律用于分支之间分流的系数的影响。
该方法在理想化模型中的平均百分比误差为+2.05%±0.04%，在重建模型中的平均百分比误差为+2.24%±0.01%，明显低于忽略侧支的方法（理想化模型中的平均百分比误差为+38.48%±10.45%，重建模型中的平均百分比误差为+30.54%±6.12%）。当假设的 Murray 定律系数与实际血流情况不一致时，百分比误差仍保持在 3.00%左右。
该方法提供了一种简单而准确的测量平均冠状动脉内血流速度的方法，有助于 IHD 的准确诊断。
