Effect of microcirculatory resistance on coronary blood flow and instantaneous wave-free ratio: A computational study

Haipeng Liu, Shanxing Ou, Panli Liu, Yuhang Xu, Yinglan Gong, Ling Xia, Xinyi Leng, Thomas Wai Hong Leung, Lin Shi, Dingchang Zheng

Research output: Contribution to journalArticle

Abstract

Background and objective: The instantaneous wave-free ratio (iFR) has been proposed to estimate the hemodynamic severity of atherosclerotic stenosis in coronary arteries. The atherosclerotic stenosis in a proximal coronary artery could change its distal microcirculatory resistance (MR). However, there is a lack of investigation about the effect of MR variation on the blood flow and iFR of stenotic coronary arteries. We aim to investigate the changes of blood flow and iFR caused by distal MR variation. Methods: Four three-dimensional models of coronary arteries were reconstructed from the computed tomography images of two normal cases and two cases with 74.9% and 96.4% (in area) stenoses in a large branch of left anterior descending artery (LAD). Computational fluid dynamics simulation was performed on each model under 6 MR situations: hyperemia as the reference situation, resting when MR was multiplied by 8/3 in all outlet branches, h-one-1.5 and h-one-2 when MR was multiplied by 1.5 and 2.0 in one branch (the stenotic, or the corresponding branch in normal case) of LAD, h-branches-1.5 and h-branches-2 when MR was multiplied by 1.5 and 2.0 in the stenotic/corresponding and its cognate branches. Flow rate and iFR of each outlet branch were then calculated and compared between different MR situations to investigate the effect of MR variation on flow rate and iFR. Results: In the 74.9% stenosed and normal cases, referring to the hyperemia situation, the increase of MR in any branch significantly decreased its flow rate and increased its iFR, with limited effect on the flow rate (10%) and iFR (>0.05) of its cognate branches. Conclusion: The increase of MR in a normal or mildly stenosed branch of coronary artery decreases its blood flow and increases its iFR, with limited effect on other branches. Whereas, the increase of MR in a severely stenotic large branch could significantly increase the flow velocity and iFR of its cognate branches.
Original languageEnglish
Article number105632
JournalComputer Methods and Programs in Biomedicine
Volume196
Early online date25 Jun 2020
DOIs
Publication statusE-pub ahead of print - 25 Jun 2020

Keywords

  • Computational fluid dynamics (CFD)
  • Coronary microvascular dysfunction (CMD)
  • Instantaneous wave-free ratio (iFR)

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