Torqueable Catheter Shaft With Segmented Stiffness for Steering
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Solution Overview
Problem
Existing catheters face challenges in navigating through complex patient anatomy due to the need for precise steering and torqueing, which requires significant manual force to combat recoiling forces, especially in irregularly shaped and tortuous arteries.
Innovation Solution
A balloon catheter design with a shaft composed of varying polymers and a tubular braid component, featuring a hypotube and pull wires, allows for improved torque transmission and steering capabilities, enabling precise alignment and navigation through anatomical features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the catheter shaft is made stiffer to maintain shape and transmit torque, then torque transmission capability is improved, but the catheter becomes harder to navigate through tortuous vasculature
Solution Approach 1:
The catheter shaft is divided into multiple segments with different stiffness characteristics - a proximal shaft portion with higher stiffness for torque transmission and a distal shaft portion with lower stiffness for navigation. This segmentation allows each portion to perform its specialized function optimally.
Solution Approach 2:
Different portions of the shaft are assigned different mechanical properties: the proximal portion uses a stiffer polymer composition (higher ratio of stiff polymer to flexible polymer) for torque transmission, while the distal portion uses a more flexible polymer composition (lower ratio of stiff polymer to flexible polymer) for navigating tortuous anatomy.
2Ease of operation
If the distal portion is made more flexible to navigate tortuous anatomy, then ease of navigation is improved, but torque transmission capability deteriorates
Solution Approach 1:
The shaft is segmented into proximal and distal portions with differentiated flexibility. The distal portion is specifically designed with higher flexibility to navigate tortuous vasculature, while the proximal portion maintains stiffness for torque transmission.
Solution Approach 2:
The distal shaft portion incorporates a polymer composition with a lower ratio of stiff polymer to flexible polymer, creating local flexibility where needed for navigation through complex anatomy while maintaining overall shaft integrity.
3Length of moving object
If the catheter shaft is made longer to reach distant target sites, then accessibility to target sites is improved, but manual force required for torqueing increases
Solution Approach 1:
The long shaft is divided into proximal and distal portions with different stiffness characteristics. The proximal portion's higher stiffness acts as a torque transmission highway, efficiently conducting rotational force from the operator to the distal portion, reducing the force needed to torque the entire catheter.
Solution Approach 2:
The proximal shaft portion uses a polymer composition optimized for torque transmission (higher ratio of stiff polymer to flexible polymer), creating a stiff section that efficiently transmits torque over the length of the catheter, reducing the manual force required despite the overall length.
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 enables efficient and precise alignment of the catheter distal end with target sites, reducing the manual force required for torqueing and enhancing navigation through complex anatomies.
Implementation Method 1
a hypotube configured for elastic deformation and having a proximal end, a distal end, a length between the proximal end and the distal end
Implementation Method 2
The outer shaft is configured for improved torque transmission such that rotation of a handle at the proximal end of the outer shaft causes the entire length of the outer shaft to rotate therewith
Data Source
AI summary
A catheter shaft includes a proximal portion with a first polymer having a first stiffness and a first portion of a tubular braid component extending within the first polymer, an intermediate portion with a second polymer having a second stiffness and a second portion of the tubular braid component extending within the second polymer, and a distal portion with a third polymer having a third stiffness, a third portion of the tubular braid component extending within the third polymer, and a hypotube extending within the third polymer. The hypotube is configured for elastic deformation and includes a sidewall cut with a pattern. Along an overlap segment of the distal portion, the third portion of the tubular braid component and the hypotube overlap each other. The outer shaft is configured for improved torque transmission.