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A hemodynamic analysis of coronary capillary blood flow based on anatomic and distensibility data
1Department of Bioengineering, University of California, San Diego, La Jolla, California 92093-0412, USA. kassab@bioeng.ucsd.edu
Insights
This study models coronary capillary blood flow using anatomical and elasticity data. Findings show capillary cross-connections reduce pressure and flow dispersion, improving cardiac blood flow dynamics.
Area of Science:
- Cardiovascular Physiology
- Biomedical Engineering
- Computational Biology
Background:
- Understanding coronary capillary blood flow is crucial for cardiac health and disease.
- Existing analyses lack comprehensive data on capillary anatomy and elasticity.
- Previous work established pig coronary capillary network geometry.
Purpose of the Study:
- To construct a mathematical model of coronary capillary blood flow.
- To investigate the spatial distribution heterogeneity of coronary blood flow.
- To analyze the impact of capillary distensibility on blood flow dynamics.
Main Methods:
- Obtained distensibility data (pressure-diameter relationship) of epicardial coronary capillaries using intravital microscopy.
- Constructed a mathematical model integrating anatomical, elasticity, rheological, and physical flow data.
- Utilized the model to simulate and examine coronary blood flow patterns.
Main Results:
- Model demonstrated that capillary cross-connections significantly reduce pressure and flow dispersions.
- Capillary cross-connections were found to decrease overall resistance to blood flow.
- Epicardial capillary compliance has a negligible effect on diastolic blood pressure drop.
Conclusions:
- The developed model provides insights into coronary blood flow heterogeneity.
- Capillary network architecture, particularly cross-connections, plays a vital role in regulating flow.
- Further research is needed on intramyocardial capillary compliance and systolic interactions.
Abstract:
An understanding of cardiac health and disease requires knowledge of the various factors that control coronary capillary blood flow. An analysis of coronary capillary blood flow based on a complete set of actual data on the capillary anatomy and elasticity does not exist. Previously, a complete set of data on the branching pattern and the vascular geometry of the pig coronary capillary network were obtained in our laboratory. In the present study, we obtained distensibility data on the coronary capillary blood vessels on the epicardial surface in the form of a pressure-diameter relationship using intravital microscopy. A mathematical model of the coronary capillary blood flow was then constructed on the basis of measured anatomic and elasticity data of the coronary capillary network, rheology of blood, physical laws governing blood flow, and appropriate boundary conditions. The constructed model was used to examine the heterogeneity of the spatial distribution of coronary blood flow, which is an important issue in coronary physiology. One interesting result of the model is that the dispersions of pressure and flow are significantly reduced in the presence of capillary cross-connections, and the resistance to flow is reduced as well. Finally, we found that the compliance of the epicardial surface capillary vessels is so small that its effect on the blood pressure drop is negligible in the diastolic state. However, the compliance of the intramyocardial capillaries remains unknown, and the interaction of the muscle contraction and blood vessel elasticity in systole remains to be studied.