Yong Enhui, Latief Javeria, Wang Yufei, Erlinge David, Dahlgren Axel, Kotecha Tushar, Muthurangu Vivek, Torii Ryo
Institute of Cardiovascular Science, University College London, London, UK; Department of Mechanical Engineering, University College London, London, UK.
Department of Mechanical Engineering, University College London, London, UK.
J Biomech. 2025 Aug;189:112679. doi: 10.1016/j.jbiomech.2025.112679. Epub 2025 Apr 6.
Conventional lumped parameter models (LPMs) simulate coronary flow incorporating intramyocardial pressure and vascular compliance, but assuming constant resistance despite its dynamic changes during myocardial contraction. We developed a coronary LPM incorporating time-varying resistance, intramyocardial pressure and vascular compliance to simulate phasic flow, critically evaluating key contributing factors. A closed-loop LPM with coronary tree was constructed. For each of Left Anterior Descending (LAD), left circumflex and Right Coronary (RCA) territories, time-varying microvascular resistanceRt and intramyocardial pressure (IMP)Pt were defined additionally to standard components. Scenarios of normal physiology and Pulmonary Hypertension (PH) were studied. Model output was assessed against in vivo measurement in the literature. The mean diastolic-systolic flow ratio (mDSFR) in LAD was underestimated by the conventional model only considering IMP (mDSFR = 1.70, vs 1.95 for in vivo measurement). Inclusion of time-varying resistance in the LPM raised mDSFR to 2.65. In the RCA, mDSFR was raised from 1.00 to 1.50 by introduction of time-varying resistance, markedly closer to 1.76 that was measured in vivo. In PH, modelled RCA flow became more diastolic dominant, represented by mDSFR of 5.35 that is closer to in vivo value of 5.83 than 2.17 which was obtained by the conventional model. The intramyocardial pressure component remained essential for regional arterial phasic changes and venous systolic-dominant flow. The simple-to-implement method of time-varying vascular resistance, developed in this study to better reflect the myocardial contraction in coronary flow analysis, facilitated an improved physiological representation compared to conventional methods, notably in the RCA especially in PH.
传统的集总参数模型（LPMs）在模拟冠状动脉血流时纳入了心肌内压力和血管顺应性，但尽管心肌收缩期间阻力会动态变化，却假定其为常数。我们开发了一种包含时变阻力、心肌内压力和血管顺应性的冠状动脉LPM，以模拟搏动性血流，并严格评估关键影响因素。构建了一个带有冠状动脉树的闭环LPM。对于左前降支（LAD）、左旋支和右冠状动脉（RCA）区域，除了标准组件外，还额外定义了时变微血管阻力Rt和心肌内压力（IMP）Pt。研究了正常生理和肺动脉高压（PH）的情况。根据文献中的体内测量结果对模型输出进行了评估。仅考虑IMP的传统模型低估了LAD中的平均舒张 - 收缩血流比率（mDSFR）（mDSFR = 1.70，而体内测量值为1.95）。在LPM中纳入时变阻力使mDSFR提高到2.65。在RCA中，通过引入时变阻力，mDSFR从1.00提高到1.50，明显更接近体内测量值1.76。在PH中，模拟的RCA血流在舒张期占主导地位的程度更高，mDSFR为5.35，比传统模型得到的2.17更接近体内值5.83。心肌内压力组件对于区域动脉搏动变化和静脉收缩期占主导的血流仍然至关重要。本研究中开发的简单易行的时变血管阻力方法，在冠状动脉血流分析中能更好地反映心肌收缩，与传统方法相比，有助于更真实地呈现生理状态，特别是在RCA中，尤其是在PH情况下。
