Polymer Coatings for Shape Memory Alloy Heart Pump Impellers
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Solution Overview
Problem
Conventional percutaneous heart pumps with fixed cross-sections can cause blood hemolysis and are often too large for percutaneous insertion, leading to increased stress on heart failure patients and potential complications.
Innovation Solution
A self-expandable and collapsible impeller housing with a metallic mesh coated with a combination of a multifunctional organosilane base coating and a biocompatible top polymer coating, which enhances lubricity and prevents fluid permeation, reducing the risk of hemolysis and improving insertion capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a fixed cross-section pump is used, then the pump can provide near full heart flow rate, but the pump is too large to be advanced percutaneously and causes increased stress on heart failure patients
Solution Approach 1:
The impeller housing transitions from a fixed cross-section design to a dynamic collapsible design that can change its cross-sectional area. The housing can be compressed to a small cross-section for percutaneous insertion and then expanded to a large cross-section to provide near full heart flow rate when in position, resolving the contradiction between insertion ease and productivity.
Solution Approach 2:
The collapsible impeller housing allows the pump components to be nested within each other during insertion, similar to nested dolls. The housing compresses to fit through the femoral artery and then expands to its functional size, enabling both percutaneous insertion and high flow rate capability.
2Reliability
If the pump surfaces are not optimized for lubricity, then the device structure remains simple, but blood hemolysis and vascular irritation occur
Solution Approach 1:
A multi-layer coating system is applied to the pump surfaces, combining different materials with complementary properties. The base coating provides adhesion to the metallic mesh, while the top coating provides enhanced lubricity and blood compatibility, reducing hemolysis without excessive complexity increase.
Solution Approach 2:
The coating system applies different material properties to different surfaces of the pump. The top coating is specifically engineered with high lubricity properties where it contacts blood and vasculature, while the base coating provides structural adhesion, creating local quality optimization for hemolysis reduction.
3Adaptability or versatility
If a metallic mesh structure is used for the impeller housing, then the housing can be self-expandable and collapsible, but the mesh structure is permeable to fluid
Solution Approach 1:
A flexible polymer coating is applied over the metallic mesh structure, forming a continuous thin film that prevents fluid permeation through the mesh openings. This coating maintains the collapsible and self-expandable properties of the mesh while eliminating fluid leakage, resolving the contradiction between adaptability and harmful fluid permeation.
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 coated impeller housing reduces blood hemolysis and facilitates smoother percutaneous insertion by minimizing friction and allowing for better blood flow, while maintaining structural integrity and preventing fluid permeation.
Implementation Method 1
a base coating that is in direct contact with the metallic mesh
Implementation Method 2
a top coating that is in direct contact with the base coating, wherein the top coating is integral with the base coating and itself to thereby render the elongate wall structure fluid-impermissible
Implementation Method 3
an impeller housing in which the impeller shaft is journaled for rotation, wherein the impeller housing comprises a metallic mesh
Data Source
AI summary
The present disclosure relates generally to percutaneous heart pumps including a self-expandable and collapsible impeller housing fabricated from a mesh of a shape memory alloy, such as nitinol, and a base polymer coating and a top polymer coating. Specifically, the present disclosure relates to highly flexible and fluid-impermissible polymer coatings having improved adherence and performance properties on the metallic surfaces of the impeller housing mesh thus improving the overall performance of the percutaneous heart pumps.