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Influence of connection geometry and SVC-IVC flow rate ratio on flow structures within the total cavopulmonary
Yottana Khunatorn1, Shankar Mahalingam, Curt G DeGroff
1Department of Mechanical Engineering, University of Colorado Boulder 80309-0427, USA.
Insights
This study numerically investigated the total cavopulmonary connection (TCPC), revealing how flow rate ratios and connection geometry impact fluid dynamics. Understanding these factors is crucial for optimizing blood flow and reducing risks in single-ventricle patients.
Area of Science:
- Cardiothoracic Surgery
- Pediatric Cardiology
- Biomedical Engineering
- Fluid Dynamics
Background:
- The total cavopulmonary connection (TCPC) is a palliative surgical procedure for single-ventricle physiology, diverting systemic venous blood to pulmonary arteries.
- Optimizing TCPC geometry is critical to minimize pressure drop in the single-ventricle circulation.
- Limited data exists on the influence of superior vena cava (SVC) and inferior vena cava (IVC) flow rate ratios on detailed fluid mechanics within TCPC.
Purpose of the Study:
- To numerically investigate the impact of varying connection geometries and SVC:IVC flow rate ratios on fluid mechanical structures within the TCPC.
- To analyze key flow parameters including shear stress, secondary flow, recirculation, stagnation, and flow separation.
- To elucidate the complex interplay between geometry, flow rates, and hemodynamic outcomes.
Main Methods:
- A numerical simulation study was conducted on TCPC configurations.
- Various connection geometries and SVC:IVC flow rate ratios were analyzed.
- Detailed examination of shear stress, secondary flow, recirculation, stagnation, and flow separation patterns.
Main Results:
- A complex interaction was observed between TCPC geometry, flow rate ratios, and detailed flow structures.
- Alterations in flow structures significantly affected local pressure distribution, influencing overall pressure drop.
- Changes in local flow dynamics resulted in variations in maximum shear stress, with potential implications for thrombus formation.
Conclusions:
- The study highlights the critical role of flow rate ratios and connection geometry in shaping TCPC hemodynamics.
- Understanding these detailed flow structures provides insights into pressure distribution and shear stress variations.
- Findings contribute to a better comprehension of fluid mechanics in complex single-ventricle physiology, aiding clinical optimization.
Abstract:
The total cavopulmonary connection (TCPC) is a palliative cardiothoracic surgical procedure used in patients with one functioning ventricle that excludes the heart from the systemic venous to pulmonary artery pathway. Blood in the superior and inferior vena cavae (SVC, IVC) is diverted directly to the pulmonary arteries. Since only one ventricle is left in the circulation, minimizing pressure drop by optimizing connection geometry becomes crucial. Although there have been numerical and in-vitro studies documenting the effect of connection geometry on overall pressure drop, there is little published data examining the effect of SVC-IVC flow rate ratio on detailed fluid mechanical structures within the various connection geometries. We present here results from a numerical study of the TCPC connection, configured with various connections and SVC:IVC flow ratios. The role of major flow parameters: shear stress, secondary flow, recirculation regions, flow stagnation regions, and flow separation, was examined. Results show a complex interplay among connection geometry, flow rate ratio and the types and effects of the various flow parameters described above. Significant changes in flow structures affected local distribution of pressure, which in turn changed overall pressure drop. Likewise, changes in local flow structure also produced changes in maximum shear stress values; this may have consequences for platelet activation and thrombus formation in the clinical situation. This study sheds light on the local flow structures created by the various connections andflow configurations and as such, provides an additional step toward understanding the detailed fluid mechanical behavior of the more complex physiological configurations seen clinically.