Foldable Intravascular Blood Pump Clearance Design
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Solution Overview
Problem
Foldable intravascular blood pumps face challenges in maintaining dimensional accuracy and preventing blood damage due to flexibility and deformation, which can lead to device failure and blood loss, especially when inserted through a catheter with a maximum diameter of 4 mm.
Innovation Solution
Increasing the clearance between the housing and impeller blades to at least 0.2 mm, with a larger aspect ratio of impeller blades and a tapering housing design to reduce blood recirculation, and using a radially delivering impeller with a configuration that allows for increased rotational speed and centrifugal forces to compensate for radial backflow, while maintaining a flexible and foldable structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the clearance between the housing and impeller blades is reduced to increase pump efficiency, then blood flow rate improves, but the risk of blood damage and device failure increases due to contact with the housing during deformation
Solution Approach 1:
The patent changes the clearance parameter from the conventional small gap (0.05-0.15mm) to a larger gap (0.2-1.0mm) to accommodate housing deformation while maintaining adequate blood flow. This parameter change resolves the contradiction by prioritizing reliability over maximum productivity in the context of foldable pump deformation.
Solution Approach 2:
The patent applies beforehand cushioning by pre-establishing a larger clearance gap between the impeller blades and housing before deformation occurs. This cushioning space prevents contact and blood damage during operational deformation, resolving the reliability concern while maintaining acceptable flow rates.
2Ease of operation
If the housing is made more flexible to facilitate catheter insertion, then ease of insertion improves, but dimensional accuracy deteriorates causing impeller-housing contact
Solution Approach 1:
The patent changes the geometric parameter of the clearance gap to be larger than conventional designs, which compensates for the dimensional inaccuracies caused by flexible housing deformation during insertion and operation.
Solution Approach 2:
The patent accepts a trade-off where the pump housing is made flexible and potentially single-use (disposable) to ensure easy insertion, while the design compensates for dimensional variability through the larger clearance approach.
3Productivity
If the rotational speed of the impeller is increased to deliver higher blood flow rates, then productivity improves, but blood damage increases due to higher shear forces
Solution Approach 1:
The patent changes the impeller geometry parameters (blade angle, curvature, and spacing) to optimize blood flow patterns at moderate rotational speeds, reducing shear forces and blood damage while maintaining adequate flow rates.
Solution Approach 2:
The patent employs dynamic blade design where the impeller blades are curved and angled to progressively accelerate blood flow, reducing turbulence and shear forces compared to straight blades, thereby minimizing blood damage at operational speeds.
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
This design enhances the reliability and efficiency of radially delivering intravascular blood pumps by reducing the risk of failure and blood damage, allowing for higher blood flow rates without excessive deformation or contact with the housing, even under external loads, and maintaining a compact size for catheter insertion.
Implementation Method 1
the blood is radially expelled from the impeller blades against the circumferential wall of the housing
Data Source
AI summary
A foldable, intravascularly insertable blood pump (10) comprises a foldable, radially delivering impeller (20) accommodated in a foldable housing or envelope (24). Axially before and behind the impeller a clearance (60) is provided between the impeller (20) and the front and back walls (32, 62) of the housing (24), the clearance being at least 0.2 mm. Preferably, the space defined between adjacent blades (54) of the impeller (20) is open towards the front wall (32) of the housing (24).