Ventricular Assist Pump-Head Coupling for Stable Impeller Clearance
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Solution Overview
Problem
Existing ventricular assist devices face challenges in efficiently pumping blood and minimizing hemolysis due to the design of the impeller and its coupling to the axial shaft.
Innovation Solution
A blood pump design featuring an axial shaft with a coupling element made of shape-memory material, which radially expands to fit around the shaft and then contracts to lock in place, coupled with an impeller having a bushing and blades that rotate with the shaft to pump blood.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the impeller is rigidly coupled to the axial shaft, then the structural strength is improved, but the efficiency of blood pumping deteriorates due to inconsistent gap between impeller blades and pump outlet tube
Solution Approach 1:
The coupling element is designed to be radially expandable and contractable, transitioning between a first configuration during delivery (providing strong rigid coupling) and a second configuration during operation (allowing axial movement). This dynamic adjustment enables the impeller to maintain a consistent gap with the pump outlet tube while preserving structural integrity.
2Reliability
If the coupling element is made rigid, then the reliability is improved, but the ease of manufacture deteriorates due to complex assembly requirements
Solution Approach 1:
The coupling element is pre-shaped with radial expandability features that enable simple assembly during delivery. The shape-memory material is pre-configured to automatically transition to a locked state upon deployment, eliminating complex assembly steps while ensuring reliable coupling.
3Productivity
If the impeller is allowed to move axially, then the efficiency of blood pumping is improved, but the stability of the coupling deteriorates
Solution Approach 1:
The coupling element provides dynamic stability by being rigid in the radial direction (maintaining stable coupling) while allowing controlled movement in the axial direction (enabling efficiency optimization). This anisotropic behavior resolves the contradiction between stability and productivity.
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 design enhances the efficiency of blood pumping and reduces hemolysis by maintaining a consistent gap between the impeller blades and the pump outlet tube, while also providing a secure and reliable coupling mechanism.
Implementation Method 1
the coupling element includes a first portion, which is disposed around the axial shaft and is made of a shape-memory material, is shaped to define one or more slits that facilitate a radial expansion of the first portion
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
Apparatus and methods are described including an axial shaft (92) and an impeller (50) configured for rotation within a subject's body. A coupling element (65) includes a first portion (66), which is disposed around the axial shaft (92), is shaped to define one or more slits (75) that facilitate a radial expansion of the first portion (66) such that the first portion (66) is placeable around the axial shaft (92), and is shape-set to have an inner diameter that is smaller than a diameter of the axial shaft (92) such that, following placement of the first portion (66) around the axial shaft (92), the first portion (66) becomes radially contracted around, and thus locked in place with respect to, the axial shaft (92). A second portion (71) of the coupling element (65) is coupled to a bushing (58, 64) of the impeller (50). Other applications are also described.