Steerable Catheter Lumen Layout for Torque and Pull-Wire Space
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Solution Overview
Problem
Existing catheters and sheaths face issues with pull wires occupying significant space, requiring reinforcement to prevent separation and tearing, leading to non-homogeneous torque properties and difficulty in navigating tortuous pathways, along with challenges in manufacturing auxiliary lumens.
Innovation Solution
The development of tubular devices with braided reinforcement configurations and lumens that change position relative to reinforcement members along the length, utilizing methods such as mandrel-based braiding to create central and auxiliary lumens with varying positions, allowing for improved space utilization and manufacturing consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If pull wires are used to impart deflection ability to the catheter, then the catheter can be steered, but the pull wire occupies significant space within the catheter body and creates non-homogeneous torque properties
Solution Approach 1:
The patent extracts the steering function from the traditional pull wire configuration. Instead of using a separate pull wire that occupies space, the steering capability is integrated into the catheter wall structure itself through the off-center lumen design. The catheter wall acts as the steering element, eliminating the need for a dedicated pull wire component.
Solution Approach 2:
The catheter wall serves multiple functions: it provides structural support, contains the off-center lumen for fluid delivery, and simultaneously acts as the steering mechanism. The off-center lumen configuration allows the catheter to deflect by manipulating the lumen's position relative to the reinforcement members, making the wall structure multi-functional.
2Reliability
If pull wires are reinforced to prevent pull through or loosening, then the mechanical actuation ability is maintained, but the torque properties become non-homogenous making it difficult to torque the catheter in tortuous pathways
Solution Approach 1:
The reinforcement members are strategically positioned relative to the off-center lumen at different locations along the catheter length. In some regions, reinforcement members are placed to prevent pull-through at the lumen, while in other regions, they are configured to allow torque transmission. This localized variation in reinforcement configuration enables both reliable actuation and torque capability in different segments of the catheter.
3Adaptability or versatility
If auxiliary lumens are located in the wall of a large bore sheath, then the device can provide additional functionality, but manufacturing consistency is difficult due to alignment challenges
Solution Approach 1:
The off-center lumen is integrated into the catheter wall structure during the initial manufacturing process, such as through co-extrusion or forming operations. The lumen's position relative to the reinforcement members is predetermined by the manufacturing tooling, ensuring consistent alignment without requiring post-manufacturing adjustment or complex assembly steps.
4Ease of operation
If the auxiliary lumen changes position relative to the reinforcement members along the length of the tubular device, then the mechanical properties and steering capability are improved, but the device complexity increases
Solution Approach 1:
The catheter design incorporates dynamic characteristics by allowing the relative position of the off-center lumen and reinforcement members to vary along the length of the device. This variation enables different mechanical properties in different segments - for example, a more compliant section for navigation and a stiffer section for actuation - without requiring multiple discrete components or complex assembly.
Data Source
AI summary
Catheters, sheaths, or other tubular devices are provided that include a proximal end, a distal end sized for introduction into a patient's body, and a steerable distal portion. The tubular device includes a primary lumen extending between the proximal and distal ends; an auxiliary lumen adjacent the primary lumen; and one or more reinforcement members including windings extending helically along at least the distal portion, at least some of the windings passing between the primary and steering element lumens and at least some of the windings surrounding both the primary and steering element lumens. In one embodiment, a steering element is slidably disposed within the auxiliary lumen. Apparatus and methods for making such tubular devices are also provided.