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Effect of microcirculatory dysfunction on coronary hemodynamics: A pilot study based on computational fluid dynamics
Yingyi Geng1, Haipeng Liu2, Xinhong Wang3
1Key Laboratory for Biomedical Engineering of Ministry of Education, Institute of Biomedical Engineering, Zhejiang University, Hangzhou, China.
Insights
Computational fluid dynamics (CFD) simulations reveal that coronary microcirculatory dysfunction (CMD) in nonobstructive coronary artery disease (CAD) reduces blood flow and pressure drop while increasing simulated FFR in the affected artery, with minimal impact on other branches.
Area of Science:
- Cardiovascular Medicine
- Biomedical Engineering
- Computational Science
Background:
- Invasive Fractional Flow Reserve (FFR) and Index of Microcirculatory Resistance (IMR) are gold standards for diagnosing Coronary Artery Disease (CAD) and Coronary Microcirculatory Dysfunction (CMD).
- The interplay between CAD and CMD remains incompletely understood.
- Non-invasive computational fluid dynamics (CFD) can elucidate the hemodynamic impact of CMD in nonobstructive CAD.
Purpose of the Study:
- To non-invasively investigate the hemodynamic effects of CMD in patients with nonobstructive CAD using CFD simulations.
- To compare hemodynamic parameters between normal microcirculatory resistance and simulated CMD conditions.
Main Methods:
- CFD simulations were performed on six cases with nonobstructive CAD and CMD in the Left Anterior Descending (LAD) artery territory.
- Two microcirculatory states were simulated: normal microcirculatory resistance (MR) and CMD (MR multiplied by the clinical IMR/cutoff ratio).
- Blood flow, translesional pressure drop (Δptl), and simulated FFR (FFRCT) were compared between states using Wilcoxon signed rank tests.
Main Results:
- CMD significantly decreased outlet flow velocity and increased FFRCT in LAD branches (p < 0.01).
- Minor decreases in Δptl (0.63–5.64 mmHg) were observed in LAD branches with CMD.
- Non-culprit branches showed no significant changes in outlet flow velocity (< 2%) or FFRCT (< 0.02).
Conclusions:
- IMR-based CFD simulations can effectively estimate the hemodynamic consequences of CMD.
- CMD in a coronary artery segment reduces its blood flow and pressure drop while increasing its FFR.
- The hemodynamic effects of CMD are localized, with minimal impact on non-culprit coronary branches.
Background:
Invasively measured fractional flow reserve (FFR) and index of microcirculatory resistance (IMR) are gold standards for the diagnosis of coronary artery disease (CAD) and coronary microcirculatory dysfunction (CMD). However, the interaction between CAD and CMD has not been comprehensively investigated. We aim to non-invasively investigate hemodynamic effect of CMD in nonobstructive CAD cases using computational fluid dynamics (CFD) simulation.
Method:
This study employed CFD simulations on six cases with nonobstructive CAD and CMD in left anterior descending artery (LAD) territories. Two microcirculatory situations were simulated: normal microcirculatory resistance (MR) situation; CMD situation where MR at the outlets of LAD branches were multiplied by the ratio of clinically measured IMR to the cutoff value. Blood flow, translesional pressure drop (Δptl), and simulated FFR (FFRCT) of LAD and non-culprit branches were compared between the two microcirculatory situations using Wilcoxon signed rank test.
Results:
The results are in accordance with existing studies and clinical measurements. Compared with normal MR, there were significant decreases in outlet flow velocity and increases in FFRCT (p < 0.01 for both in Wilcoxon signed rank tests) in LAD branches with CMD, with minor decreases (0.63-5.64 mmHg) in Δptl. There was no significant influence on outlet flow velocity (< 2%) and FFRCT (< 0.02) in non-culprit branches (p > 0.05 for both).
Conclusion:
IMR-based CFD simulation could estimate hemodynamic effects of CMD. CMD in a coronary artery branch can decrease its blood flow and Δptl, increase its FFR, with little effect on non-culprit branches.
