Low-Profile Steerable Catheter With Deformable Pull-Ring
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Solution Overview
Problem
Steerable catheters face challenges in maintaining a small outer diameter for percutaneous advancement while maximizing the inner diameter for article passage, as pull-wires coupled to the pull-ring often thicken the catheter wall, increasing the outer diameter and reducing the inner diameter.
Innovation Solution
A steerable catheter design featuring a flexible tube with a pull-ring that is elastically deformable between two eccentricity states, allowing the catheter to maintain a small outer diameter during advancement and accommodate larger articles by transitioning to a larger inner diameter when needed, utilizing a pull-ring that can change shape to accommodate both states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If pull-wires are coupled to the pull-ring with overlapping arrangement to maximize contact and mechanical strength, then the coupling strength is improved, but the wall thickness increases, thereby increasing the outer diameter and reducing the inner diameter
Solution Approach 1:
The pull-ring is designed to be dynamically deformable between a first state (lower eccentricity) and a second state (higher eccentricity). During percutaneous advancement, the pull-ring assumes the first state to minimize the outer diameter. When articles need to be passed through, it transitions to the second state to maximize the inner diameter, thus resolving the contradiction between maintaining small outer diameter and providing large inner diameter.
Solution Approach 2:
The pull-ring's geometric parameters (eccentricity, major axis, minor axis) are changed between two distinct states. In the first state, the pull-ring has lower eccentricity for compact outer diameter. In the second state, it has higher eccentricity to expand the inner lumen diameter, allowing the system to adapt to different operational requirements without compromising either parameter permanently.
2Stability of the object's composition
If the pull-ring is made rigid to maintain its shape during advancement, then the structural stability is improved, but the ability to accommodate articles of varying sizes is reduced
Solution Approach 1:
The pull-ring transitions from a rigid-like stable structure in the first state during advancement to a dynamically adaptable configuration in the second state when articles are passed through. This dynamic transformation allows the same structure to provide both stability during insertion and adaptability during the procedure.
Solution Approach 2:
The pull-ring is designed with an elliptical geometry that can be segmented into different effective configurations through elastic deformation. The ability to reconfigure the elliptical shape into different eccentricity states allows the single pull-ring structure to serve multiple functions: maintaining stability during advancement and accommodating various article sizes during the procedure.
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 percutaneous advancement with minimal wall thickness, allowing for larger articles to be passed through the catheter without increasing the outer diameter, thereby optimizing both the outer and inner diameters for different stages of the procedure.
Implementation Method 1
The pull-ring is shaped and is elastically deformable such that, (i) during advancement of the catheter through the vasculature, an outer diameter of the tube is not adversely increased by the presence of the at least one pull-wire coupled to the pull-ring, and (ii) during advancement of an article through the lumen of the tube, an inner diameter of the tube is not adversely reduced
Data Source
AI summary
A steerable catheter comprises a flexible tube having a proximal portion and a distal portion and comprising a circumferential wall that defines an elongate lumen between the proximal portion and the distal portion. A pull-wire can extend, in association with the wall, from the proximal portion to the distal portion. A pull-ring can be coupled to the wall at the distal portion such that the pull-ring circumscribes the lumen, and coupled to the pull-wire, such that pulling on the pull-wire bends the distal portion. The pull ring can have (i) a first state in which the pull-ring is elliptical and has a first eccentricity, and (ii) a second state in which the pull-ring is elliptical and has a second eccentricity that is smaller than the first eccentricity. The pull ring can be biased toward the first state, and deformable to the second state. Other embodiments are also described.