Department of Information Engineering, School of Electronics and Information, Northwestern Polytechnical University, Xi'an, Shaanxi, China.
Department of Cardiology, No. 971 Hospital of the PLA Navy, Qingdao, Shandong, China.
Med Eng Phys. 2024 Aug;130:104193. doi: 10.1016/j.medengphy.2024.104193. Epub 2024 Jun 10.
Accurate measurement of pulsatile blood flow in the coronary arteries enables coronary wave intensity analysis, which can serve as an indicator for assessing coronary artery physiology and myocardial viability. Computational fluid dynamics (CFD) methods integrating coronary angiography images and fractional flow reserve (FFR) offer a novel approach for computing mean coronary blood flow. However, previous methods neglect the inertial effect of blood flow, which may have great impact on pulsatile blood flow calculation. To improve the accuracy of pulsatile blood flow calculation, a novel CFD based method considering the inertia term is proposed.
A flow resistance model based on Pressure-Flow vs.Time curves is proposed to model the resistance of the epicardial artery. The parameters of the flow resistance model can be fitted from the simulated pulsating flow rates and pressure drops of a specific mode. Then, pulsating blood flow can be calculated by combining the incomplete pressure boundary conditions under pulsating conditions which are easily obtained in clinic. Through simulation experiments, the effectiveness of the proposed method is validated in idealized and reconstructed 3D model of coronary artery. The impacts of key parameters for generating the simulated pulsating flow rates and pressure drops on the accuracy of pulsatile blood flow calculation are also investigated.
For the idealized model, the previously proposed Pressure-Flow model has a significant leading effect on the computed blood flow waveform in the moderate model, and this leading effect disappears with the increase of the degree of stenosis. The improved model proposed in this paper has no leading effect, the root mean square error (RMSE) of the proposed model is low (the left coronary mode:≤0.0160, the right coronary mode:≤0.0065) for all simulated models, and the RMSE decreases with an increase of stenosis. The RMSE is consistently small (≤0.0217) as the key parameters of the proposed method vary in a large range. It is verified in the reconstructed model that the proposed model significantly reduces the RMSE of patients with moderate stenosis (the Pressure-Flow model:≤0.0683, the Pressure-Flow vs.Time model:≤0.0297), and the obtained blood flow waveform has a higher coincidence with the simulated reference waveform.
This paper confirms that ignoring the effect of inertia term can significantly affect the accuracy of calculating pulsatile blood flow in moderate stenosis lesions, and the new method proposed in this paper can significantly improves the accuracy of calculating pulsatile blood flow in moderate stenosis lesions. The proposed method provides a convenient clinical method for obtaining pressure-synchronized blood flow, which is expected to facilitate the application of waveform analysis in the diagnosis of coronary artery disease.
准确测量冠状动脉中的脉动血流可进行冠状动脉波强度分析，作为评估冠状动脉生理学和心肌活力的指标。整合冠状动脉造影图像和血流储备分数（FFR）的计算流体动力学（CFD）方法为计算平均冠状动脉血流提供了一种新方法。然而，以前的方法忽略了血流的惯性效应，这可能对脉动血流计算有很大影响。为了提高脉动血流计算的准确性，提出了一种考虑惯性项的新型 CFD 方法。
提出了一种基于压力-流量与时间曲线的流阻模型来模拟心外膜动脉的阻力。该流阻模型的参数可以通过特定模式下模拟的脉动流量和压降拟合得到。然后，通过结合临床中容易获得的脉动条件下不完全压力边界条件，计算脉动血流。通过仿真实验，在理想化和重建的冠状动脉 3D 模型中验证了所提出方法的有效性。还研究了生成模拟脉动流量和压降的关键参数对脉动血流计算准确性的影响。
对于理想化模型，以前提出的压力-流量模型在中度模型中对计算血流波形有显著的超前效应，随着狭窄程度的增加，这种超前效应消失。本文提出的改进模型没有超前效应，对于所有模拟模型，该模型的均方根误差（RMSE）都很低（左冠状动脉模型：≤0.0160，右冠状动脉模型：≤0.0065），并且 RMSE 随着狭窄程度的增加而减小。当所提出方法的关键参数在较大范围内变化时，RMSE 始终很小（≤0.0217）。在重建模型中验证了该模型可显著降低中度狭窄患者的 RMSE（压力-流量模型：≤0.0683，压力-流量与时间模型：≤0.0297），并且获得的血流波形与模拟参考波形具有更高的一致性。
本文证实，忽略惯性项的影响会显著影响中度狭窄病变中脉动血流计算的准确性，而本文提出的新方法可显著提高中度狭窄病变中脉动血流计算的准确性。该方法为获得与压力同步的血流提供了一种便捷的临床方法，有望促进波型分析在冠状动脉疾病诊断中的应用。
