Variable-Stiffness Imaging Window for Intravascular Catheters
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Solution Overview
Problem
Current intravascular ultrasound imaging catheters with a single flexural modulus face limitations in navigating coronary arteries due to a trade-off between pushability and trackability, and often introduce measurement inaccuracies and image artifacts.
Innovation Solution
A variable stiffness imaging window is created by using sections of polyethylene materials with different flexural moduli, allowing for a progressive change in stiffness along the catheter length, optimizing pushability and trackability while maintaining uniform imaging performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an imaging window with a single flexural modulus is used, then measurement accuracy is maintained, but catheter pushability and trackability are compromised
Solution Approach 1:
The imaging window is divided into multiple sections along its length, with each section having a different flexural modulus. The proximal section has a higher flexural modulus for pushability, while the distal section has a lower flexural modulus for trackability. This local variation in material properties allows the catheter to exhibit both strong pushability and good trackability simultaneously, resolving the contradiction between ease of operation and measurement precision.
Solution Approach 2:
The imaging window is segmented into multiple discrete sections, each made from polyethylene material with a different flexural modulus. This segmentation allows independent optimization of mechanical properties in different regions while maintaining uniform ultrasonic transmission characteristics across all sections, thus improving catheter navigation without compromising measurement accuracy.
2Ease of operation
If an imaging window with variable flexural modulus is used, then catheter pushability and trackability are improved, but image artifacts and measurement inaccuracies are introduced
Solution Approach 1:
The flexural modulus parameter is changed along the length of the imaging window by using different polyethylene materials with varying stiffness properties. However, all sections maintain equivalent ultrasonic transmission properties, ensuring that the parameter change affects only mechanical performance (pushability and trackability) without introducing image artifacts or measurement inaccuracies.
Solution Approach 2:
The imaging window is constructed as a composite structure with multiple sections made from different polyethylene materials, each having distinct flexural modulus values. This composite approach allows the catheter to achieve optimal pushability and trackability while maintaining uniform imaging performance, as all polyethylene sections are substantially transparent to ultrasound energy.
3Ease of operation
If the stiffness of the imaging window is varied with length, then the balance between pushability and trackability is optimized, but manufacturing complexity increases
Solution Approach 1:
The imaging window is segmented into multiple discrete sections that can be manufactured separately and then assembled by bonding. This segmentation simplifies the manufacturing process compared to creating a continuously variable stiffness structure, as each section can be produced using standard extrusion processes with different material formulations, reducing overall manufacturing complexity while achieving the desired stiffness variation.
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 variable stiffness imaging window enhances the ability to navigate tortuous coronary arteries by optimizing catheter pushability and trackability, reducing image artifacts and ensuring accurate ultrasound measurements.
Implementation Method 1
The first and second materials are substantially transparent to ultrasound energy
Data Source
AI summary
An imaging window of an imaging catheter includes a first imaging window section and a second imaging window section. The first imaging window section has a finite length and is formed from a first material having a flexural modulus. The second imaging window section has a finite length and is formed from a second material having a flexural modulus. The flexural modulus of the first material is different than the flexural modulus of the second material.