Distal Bearing Support for Catheter Pump Tip Gap Stability
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Solution Overview
Problem
There is a need for a minimally-invasive heart pump that can provide elevated flow rates with reduced risk of hemolysis and thrombosis, capable of being inserted percutaneously and supporting both left and right sides of the heart, while minimizing adverse events.
Innovation Solution
A catheter pump with an expandable cannula and impeller assembly, featuring a distal bearing support structure to maintain separation between the impeller and cannula, reducing bending loads and minimizing hemolysis risk, and a re-sealable member to facilitate guidewire withdrawal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the impeller rotates at high speed to increase flow rate, then productivity is improved, but hemolysis risk increases
Solution Approach 1:
The distal bearing support structure is pre-configured to maintain optimal separation between the impeller and cannula wall before the pump operates. This preliminary positioning ensures that when the impeller rotates at high speeds to achieve high flow rates (productivity improvement), the blood flow path remains clear and uniform, preventing turbulent flow and shear stress that would cause hemolysis. The support structure proactively establishes the correct geometric relationship between moving and stationary components.
Solution Approach 2:
The distal bearing support acts as an intermediary element between the impeller assembly and the cannula wall. It mediates the spatial relationship by maintaining a consistent gap, which allows the impeller to rotate at high speed for increased productivity while the intermediary support prevents direct contact or excessive clearance that would create harmful flow patterns and reduce hemolysis risk.
2Ease of operation
If the cannula is made flexible for percutaneous insertion, then ease of operation is improved, but structural stability deteriorates
Solution Approach 1:
The cannula is segmented into multiple sections with varying degrees of flexibility and rigidity. The distal portion containing the impeller assembly has enhanced structural stability to maintain precise clearance during operation, while proximal sections remain more flexible to enable percutaneous insertion through blood vessels. This segmentation allows each section to optimize its mechanical properties for its specific function.
Solution Approach 2:
The cannula transitions from a flexible state during insertion to a stabilized state during operation. The distal bearing support structure provides dynamic stabilization by maintaining constant separation between the impeller and cannula wall, allowing the cannula to be flexible enough for insertion while ensuring structural stability when the pump is operational.
3Productivity
If the impeller clearance is reduced to improve pump efficiency, then productivity is improved, but bending loads increase
Solution Approach 1:
The distal bearing support serves as an intermediary that maintains the optimized impeller-to-cannula clearance. By providing continuous support at the distal end, it allows the impeller to operate with minimal clearance for high efficiency while the intermediary support structure absorbs and distributes the bending loads, preventing them from concentrating on the impeller shaft or causing excessive stress on the cannula.
Solution Approach 2:
The distal bearing support provides a counterbalancing force that offsets the bending loads generated by the close-clearance impeller operation. This counter-support mechanism allows the system to maintain high productivity through reduced clearance while the anti-weight support compensates for the increased mechanical stresses, distributing loads more evenly throughout the assembly.
Data Source
AI summary
In various embodiments, a catheter pump is disclosed herein. The catheter pump can include an elongated catheter body having a distal portion including an expandable cannula having an inlet and an outlet. The expandable cannula can have a delivery profile and an operational profile larger than the delivery profile. An impeller assembly can include an impeller shaft, and an impeller body can include one or more blades. The impeller blades can draw blood into the cannula when rotated. Further, an expandable support can have a mounting portion disposed on the impeller shaft distal of the impeller body and a cannula contact portion for reducing a change in tip gap due to bending of the cannula. The cannula contact portion can be disposed distal of the mounting portion.