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Velocity and wall shear stress patterns in the human right coronary artery
A Kirpalani1, H Park, J Butany
1Institute of Biomedical Engineering, University of Toronto, Ontario, Canada.
Insights
This study modeled human right coronary artery blood flow dynamics. Lower inner wall shear stress in the proximal segment may contribute to atherosclerosis development.
Area of Science:
- Cardiovascular science
- Biomedical engineering
- Fluid dynamics
Background:
- Coronary atherosclerosis significantly impacts human health.
- Quantifying blood flow dynamics in the right coronary artery is crucial but challenging.
- Existing research lacks detailed characterization of flow patterns and wall shear stress in this specific artery.
Purpose of the Study:
- To develop and apply a technique for quantifying blood flow dynamics in a human right coronary artery model.
- To investigate the relationship between blood flow patterns, wall shear stress, and the localization of coronary atherosclerosis.
- To analyze the three-dimensional geometry and its influence on flow characteristics.
Main Methods:
- Constructed a rigid flow model from a human right coronary artery cast.
- Utilized a laser photochromic method to measure velocity and wall shear stress.
- Simulated steady flow (Reynolds numbers 500, 1000) and unsteady flow (Womersley parameter 1.82, peak Reynolds number 750).
- Characterized the artery's 3D geometry, focusing on curvature variations.
Main Results:
- Identified the proximal region as having the largest spatial variation in curvature.
- Observed high shear stresses on the outer wall and lower shear stresses on the inner wall in the proximal segment.
- Found that inner wall shear stress was low but not negative under simulated flow conditions.
Conclusions:
- Low shear stress on the inner wall of the proximal right coronary artery may be a contributing factor to atherosclerosis localization.
- The significant difference between outer and inner wall shear stresses could also play a role in atherosclerosis development.
- This study provides critical insights into the biomechanics of the coronary artery, relevant for understanding and potentially treating atherosclerosis.
Abstract:
Blood flow dynamics in the human right coronary artery have not been adequately quantified despite the clinical significance of coronary atherosclerosis. In this study, a technique was developed to construct a rigid flow model from a cast of a human right coronary artery. A laser photochromic method was used to characterize the velocity and wall shear stress patterns. The flow conditions include steady flow at Reynolds numbers of 500 and 1000 as well as unsteady flow with Womersley parameter and peak Reynolds number of 1.82 and 750, respectively. Characterization of the three-dimensional geometry of the artery revealed that the largest spatial variation in curvature occurred within the almost branch-free proximal region, with the greatest curvature existing along the acute margin of the heart. In the proximal segment, high shear stresses were observed on the outer wall and lower, but not negative, stresses along the inner wall. Low shear stress on the inner wall may be related to the preferential localization of atherosclerosis in the proximal segment of the right coronary artery. However, it is possible that the large difference between the outer and inner wall shear stresses may also be involved.