Steerable Catheter Pull-Ring for Small OD and Larger Lumen
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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 existing designs with pull-wires coupled to pull-rings 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 eccentric states, allowing it to maintain a small outer diameter during advancement and accommodate larger articles by transitioning to a larger inner diameter when needed, using a pull-ring with adjustable eccentricity and a system of pull-wires that are slidable and coupled to the tube wall.
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/or reducing the inner diameter
Solution Approach 1:
The pull-ring is designed to be elastically deformable between a first state (during advancement) and a second state (during article passage). This dynamic transformation allows the pull-ring to adapt its configuration, enabling the pull-wires to be arranged in a way that maximizes coupling strength without permanently increasing the outer diameter. The elastic deformability permits the structure to optimize its properties for different operational phases.
Solution Approach 2:
The pull-ring's eccentricity is changed between two states. In the first state, the pull-ring has a first eccentricity optimized for advancement with minimal outer diameter. In the second state, the pull-ring transforms to a second eccentricity that accommodates the pull-wire arrangement needed for maximum coupling strength during article passage. This parameter change resolves the contradiction by allowing different optimal configurations at different times.
2Ease of operation
If the outer diameter is minimized for percutaneous advancement, then the ease of advancement through anatomy is improved, but the inner diameter is reduced, limiting the size of articles that can be passed through
Solution Approach 1:
The catheter system dynamically transforms between two configuration states. During percutaneous advancement, the pull-ring is in its first state that minimizes the outer diameter for easy passage through anatomy. After advancement, the system transitions to the second state where the pull-ring's configuration change allows for larger inner diameter to accommodate bigger articles. This dynamic adaptability resolves the contradiction between small outer diameter for advancement and large inner diameter for article passage.
Solution Approach 2:
The pull-ring is designed with features that allow it to be segmented or divided into different functional zones during operation. The elastic deformability and eccentricity change enable different portions of the pull-ring to be optimized for different functions: minimal outer diameter during advancement, and maximized inner diameter during article passage. This segmentation of functional requirements across different operational phases resolves the size contradiction.
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 comprising a circumferential wall, along which a pull-wire extends, and that defines an elongate lumen from the tube's proximal portion to the tube's distal portion. A pull-ring, circumscribing the lumen at the distal portion, is coupled to the pull-wire and the wall such that pulling on the pull-wire bends the distal portion. The pull ring can be: (i) biased toward a first state in which the pull-ring is elliptical, and (ii) deformable to a second state in which the pull-ring has a lesser eccentricity. The tube can have a delivery state in which the pull-ring is in the first state and the distal portion's outer surface has a first surface eccentricity, and a working state in which the pull-ring is in the second state and the outer surface has a second, greater surface eccentricity. Other embodiments are also described.