Rapid Exchange Catheter Junction Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Rapid exchange catheters face challenges with resistance to kinking and maintaining flexibility, particularly due to abrupt changes in material properties between the stiff hypotube and flexible distal section, which complicates navigation through tortuous vasculature and affects pushability and trackability.
Innovation Solution
A rapid exchange catheter assembly with a proximal tube, distal tube, and guide wire tube bonded together at a junction, featuring a taper in the distal tube for increased flexibility and a skived portion of the hypotube for transition, allowing for improved force transmission and reduced kinking risk, with bonding achieved through heat treatment or adhesives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a metal hypotube with high stiffness is used for the proximal shaft portion, then push force transmission is improved, but the risk of twist and kinking increases due to abrupt property change
Solution Approach 1:
The catheter employs different material properties in different sections: the proximal shaft portion uses stiff metal hypotube for force transmission, while the distal portion uses flexible plastics for conformability. A transition zone with intermediate properties bridges these sections, allowing each region to have optimized local characteristics without causing abrupt property changes that lead to kinking.
Solution Approach 2:
The catheter is constructed as a composite structure combining metal hypotube and flexible plastics materials. The transition zone creates a gradual property change between these dissimilar materials, preventing abrupt stiffness transitions that would cause twisting and kinking while maintaining both force transmission capability and flexibility.
2Ease of operation
If a flexible plastics distal portion is bonded to stiff hypotube, then flexibility and ability to bend are improved, but resistance to kinking deteriorates due to abrupt property change
Solution Approach 1:
The distal portion uses flexible plastics material to enable bending and conforming to body lumens, while the proximal shaft uses stiff metal for force transmission. The transition zone provides intermediate properties that gradually bridge these contrasting material characteristics, preventing abrupt property changes that would cause kinking.
Solution Approach 2:
The transition zone creates a gradual parameter change in stiffness and rigidity between the flexible distal portion and stiff proximal shaft. This progressive parameter transition prevents sudden property changes that would lead to twisting and kinking, while still allowing the distal portion to remain flexible for navigation.
3Ease of operation
If guide wire runs through entire catheter lumen, then guidance to application site is improved, but excess guide wire length is required which complicates the procedure
Solution Approach 1:
The guide wire is extracted from running through the entire catheter lumen and is instead confined to the distal portion only. The proximal shaft portion is made independent of the guide wire, allowing the guide wire to be shorter and eliminating the need for excess guide wire length that would complicate the procedure.
Solution Approach 2:
The catheter is segmented into a proximal shaft portion and a distal portion with different guide wire configurations. The proximal shaft operates independently of the guide wire, while the distal portion maintains guide wire connection for guidance. This segmentation allows the guide wire to be shorter and eliminates procedural complexity.
4Adaptability or versatility
If rapid exchange catheter design is used, then ease of exchange between different catheters is improved, but resistance to kinking deteriorates
Solution Approach 1:
The rapid exchange catheter maintains the independent proximal shaft design for ease of exchange while incorporating a transition zone with intermediate material properties to prevent kinking. The distal portion remains guide-wire dependent for guidance, creating a balanced design that achieves both exchangeability and kinking resistance.
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 solution enhances pushability and trackability through the vasculature by maintaining flexibility while reducing kinking, as demonstrated by reduced force requirements for advancing the catheter through tortuous paths and improved bonding strength.
Implementation Method 1
The bonding is preferably achieved by heat treatment.
Implementation Method 2
The bonding may also be achieved by use of an adhesive.
Data Source
AI summary
A rapid exchange catheter includes a stiff proximal tube and a relatively flexible tapered distal tube, a guide wire tube being provided in the distal tube, with an aperture for access to the guide wire lumen being provided at the junction between the distal tube and the proximal tube, the tubes being bonded together at their junction.