Pressure Drop across Aortic Valve with Aortic Stenosis Using 3D Model and Pulsatile Flow
Fabela, Madeline
2023
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Stenosis of the aortic valve or aortic stenosis can be caused by calcium buildup that leads to a reduction in the free area of the valve which restrains the flow of blood to the aorta. A 3D-printed model of a patient’s stenosis was created using CT scan data provided by Tufts Medical Center. The 3D-printed model was used to physically measure the pressure gradient produced when tested with steady ... read moreand pulsatile flow conditions. Steady flow was used to validate the 3D-printed model as a representation of a patient’s aortic valve. Dynamic similarity allowed for water to be used instead of blood. Matching Reynolds and Womersley numbers for blood and water were used to find the water flow rates and frequency that were necessary to match hemodynamic conditions. The resulting water flow rate for steady conditions in the experimental setup was about 712 mL/min. There were 20 trials done for the steady flow simulation with a resulting average blood pressure of 484.21 mmHg. This value is above the permissible range for patients with aortic stenosis. It was determined that the results confirmed that with more accurate flow conditions, the 3D-printed model could prove to be an accurate replica of a patient’s aortic valve. Therefore, the study was continued with pulsatile flow. The flow changed over time based on hemodynamic conditions but was limited by the operational restrictions of the pump used. Blood flow through the aorta was plotted versus time and used as a source for matching water flow rates every 0.2 seconds to blood flow rates. Initially, the 5 flow rates were extracted from the data but due to the backflow of blood and other limitations, there were only 3 real flow points that were tested. The final five water flow rates after conversions and calibrations were done were 2796.13 mL/min, 0 mL/min, 201.3 mL/min, 34.77 mL/min, and 0 mL/min. These took a total of 2.83 seconds to loop through the 3D-printed model, which matched the frequency of blood flow. For the pulsatile flow simulation, there were 4 trials total each with 9 cycles of the five flows. The average pressure gradients for blood that corresponded to the three main flows were 304.19 mmHg, 34.08 mmHg, and 0 mmHg. These results are within real pressure gradients experienced by patients with severe aortic stenosis, confirming that 3D-printed models of patients’ aortas can provide health professionals with patient-specific blood pressure gradients.
Thesis (B.S.M.E.)--Tufts University, 2023.
Submitted to the Dept. of Mechanical Engineering.read less - ID:
- w3763n488
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