Blood Pump Housing Aperture Edge Geometry for Hemolysis Reduction
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Solution Overview
Problem
Blood pump assemblies cause hemolysis and damage to blood due to the high shear stresses induced by sharp edges in the blood exhaust apertures.
Innovation Solution
The blood pump housing includes blood exhaust apertures with blunted inner edges, either chamfered or rounded, which reduce shear stresses and minimize hemolysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If standard sharp aperture edges are used in blood pump housing, then manufacturing is simpler, but hemolysis increases due to high shear stresses
Solution Approach 1:
The patent applies curvature by rounding the inner edges of blood exhaust apertures with a specified radius (e.g., 0.5mm to 2mm). This replaces sharp edges with curved surfaces, eliminating stress concentration points and reducing shear stresses on blood cells during flow, thereby significantly reducing hemolysis while maintaining manufacturing feasibility through standard machining or forming processes.
Solution Approach 2:
The patent changes the geometric parameter of the aperture edge from sharp (zero radius) to rounded (finite radius). By specifying a particular radius range for the rounded edge, the design optimizes the balance between reducing hemolysis (by lowering shear stress) and maintaining acceptable manufacturing complexity. This parameter modification directly addresses the technical contradiction.
2Object-affected harmful factors
If chamfered or rounded edges are used in blood exhaust apertures, then hemolysis is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent specifies concrete parameter ranges for the rounded edges (radius of 0.5mm to 2mm) to quantify the geometric modification. This transforms a complex design concept into a manufacturable solution with defined tolerances, reducing the perceived complexity while achieving the hemolysis reduction goal.
3Device complexity
If sharp edges are used in blood pump housing, then device structure is simpler, but blood flow shear stress increases causing damage
Solution Approach 1:
The patent introduces curvature at the aperture inner edges through rounding with a specified radius. This geometric modification smooths the blood flow path, eliminates flow separation and vortex formation that occur at sharp edges, and significantly reduces shear stresses exerted on blood cells, thereby preventing hemolysis while adding minimal structural complexity.
Solution Approach 2:
The patent applies the rounded edge feature specifically at the inner edges of blood exhaust apertures where blood flow transitions occur, rather than modifying the entire housing structure. This localized application of curvature addresses the shear stress problem at the critical location while maintaining the simplicity of the overall device structure.
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 use of chamfered or rounded inner edges in the blood exhaust apertures significantly reduces hemolysis by over 50% compared to standard aperture edges, minimizing blood damage during pumping.
Implementation Method 1
The use of chamfered inner edges on the blood exhaust apertures allows the blood to follow a flow pattern in which the shear stresses may be decreased compared to flow past sharp or unblunted edges
Data Source
AI summary
Blood pump assemblies and methods of manufacturing and operating blood pump assemblies are provided. The blood pump assembly includes a pump and an impeller blade rotatably coupled to the pump. The blood pump assembly also includes a pump housing component sized for passage through a body lumen and coupled to the pump. The pump housing component includes a peripheral wall extending about a rotation axis of the impeller blade. The peripheral wall includes an inner peripheral wall surface and an outer peripheral wall surface. The peripheral wall also includes one or more blood exhaust apertures. Each blood exhaust aperture in the one or more blood exhaust apertures is defined by an inner aperture edge and an outer aperture edge. Each inner aperture edge is chamfered between the inner peripheral wall surface and the outer peripheral wall surface.