Centrifugal Cardiac Pump Impeller Blade Geometry for Hemolysis Reduction
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Solution Overview
Problem
Current centrifugal flow blood pumps used as ventricular assist devices face issues such as high shear stresses leading to hemolysis, thrombosis due to flow stagnation, and challenges in optimizing hydraulic output, efficiency, and radial force to minimize blood damage.
Innovation Solution
The design incorporates an impeller with blades having a specific wrap angle, blade angles at the hub and shroud, blade lean angle, and blade thickness, which helps in straightening the flow field, reducing vorticity, and improving hydrodynamic efficiency, thereby minimizing shear stress and hemolysis risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high rotational speeds are used to improve pump efficiency and hydraulic output, then productivity is improved, but shear stress on blood increases causing hemolysis
Solution Approach 1:
The patent changes the geometric parameters of the impeller blades, specifically introducing a wrap angle between 100°-125°, blade angle at hub between 30°-40°, blade angle at shroud between 55°-62.5°, and blade lean angle between 0°-25°. These parameter modifications optimize the flow field to reduce shear stress while maintaining high rotational speed operation, thereby improving pump efficiency without increasing hemolysis
Solution Approach 2:
The patent employs curved blade surfaces with specific wrap angles and lean angles to create a smoother flow field. The curved geometry reduces flow separation and vortex formation, minimizing shear stress on blood cells during high-speed rotation, thus preventing hemolysis while maintaining productivity
2Device complexity
If small clearances between rotor and housing are used to reduce device size, then device complexity is reduced, but shear stress increases causing hemolysis
Solution Approach 1:
The patent modifies the blade geometric parameters including wrap angle (100°-125°), blade angles at hub (30°-40°) and shroud (55°-62.5°), and blade lean angle (0°-25°) to optimize the flow field in the small clearance region. These changes reduce flow separation and vortex formation, minimizing shear stress on blood cells while maintaining compact device dimensions
3Ease of manufacture
If conventional impeller geometry is used to simplify manufacturing, then ease of manufacture is improved, but flow stagnation areas create thrombosis risk
Solution Approach 1:
The patent introduces specific blade geometric parameters including wrap angle (100°-125°), blade angle at hub (30°-40°), blade angle at shroud (55°-62.5°), and blade lean angle (0°-25°) to eliminate flow stagnation areas. These parameter optimizations prevent blood clot formation while maintaining manufacturing feasibility through standardized blade construction methods
4Power
If high rotational speeds are used to improve hydraulic output, then power is improved, but vortex structures increase blood damage potential
Solution Approach 1:
The patent employs curved blade surfaces with specific wrap angles (100°-125°) and lean angles (0°-25°) to create a smoother, more coherent flow field that suppresses vortex formation. This curved geometry maintains high hydraulic output at rotational speeds between 5,000-15,000 RPM while minimizing vortex-induced blood cell damage
Solution Approach 2:
The patent optimizes blade geometric parameters including wrap angle, blade angle at hub, blade angle at shroud, and blade lean angle to reduce flow separation and vortex structures. These parameter changes enable high power output while minimizing vortex formation that would otherwise cause blood damage at operating speeds of 5,000-15,000 RPM
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed design reduces hemolysis and thrombosis risks by minimizing shear stress and stagnation zones, achieving low hemolysis values as confirmed by in-silico, in-vitro, and acute in-vivo tests, and providing improved hydraulic performance.
Implementation Method 1
a magnetic drive means magnetically coupled to said impeller for actuating the rotation of impeller (3)
Implementation Method 2
Centrifugal flow blood pumps conventionally comprise a housing defining a pumping chamber and having an axial blood inlet and a tangential volute defining a blood outlet. A rotatable impeller as rotor is housed inside the pumping chamber and is adapted to pressurize blood entering the pumping chamber for exiting at the blood outlet.
Data Source
Figure 1~2
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Figure 5~6
AI summary
The present invention relates to a centrifugal flow pump that is suitable for pumping blood that can be used as a left ventricular assist device (LVAD). The present invention more specifically relates to a centrifugal blood pump (100) for effectuating conveying of blood in between an axial inlet (22) and a tangential outlet (23), said centrifugal blood pump (100) comprising a pumping chamber housing an impeller (3) attached onto a rotating hub (11) centered on an axis of rotation and a magnetic drive means magnetically coupled to said impeller (3) for rotating impeller (3), and said impeller (3) comprising blades (9, 10) having a geometry that is configured to minimize hemolysis and thrombosis in said centrifugal blood pump (100).