Steerable Catheter Tip Ring Saddle Tension Distribution
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Solution Overview
Problem
Current guiding systems for accessing body cavities, such as the heart, face challenges in steering catheters to precise orientations within complex anatomical structures like the mitral valve, due to limitations in steerability, stability, and manufacturing costs, particularly with pre-shaped access sheaths and pullwire-based steering mechanisms.
Innovation Solution
A steerable catheter guidance system featuring a tip ring with saddles to distribute tension over a larger surface area, reducing stress on pullwires and preventing unwanted rotation through a keying feature using chemically compatible plastic keys with glass microstructure fillers, allowing for adjustable curvature and precise positioning within body cavities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If pre-shaped access sheaths with fixed curvature are used to direct instruments into body cavities, then the catheter can maintain a stable shape once positioned, but the curvature cannot be altered and extensive pre-surgical planning is necessary to determine the correct curvature
Solution Approach 1:
The catheter incorporates a shape memory alloy braid that enables dynamic transformation between different curved configurations. The braid can be actuated to transition the catheter from a delivery configuration to a working configuration with different curvatures, allowing the same catheter to adapt to various anatomical pathways without requiring pre-surgical determination of a fixed curvature.
Solution Approach 2:
The catheter's curvature parameters can be changed on-demand through actuation of the shape memory alloy braid. This allows the catheter to transform between different radial and longitudinal curvatures, enabling a single catheter design to serve multiple anatomical configurations and eliminating the need for extensive pre-surgical planning to select the appropriate fixed curvature.
2Measurement precision
If multiple instruments are used during a procedure to access different target tissues, then each device can be steered toward its specific target, but the time and cost of the procedure increases and the risk of misalignment increases
Solution Approach 1:
The catheter system provides universal steering capability that can direct multiple different instruments toward their respective targets within the same body cavity. The shape memory alloy braid enables the catheter to be configured with different curvatures to access various anatomical structures, allowing a single catheter to serve multiple functions and reduce the need for multiple specialized instruments.
Solution Approach 2:
The dynamic reconfigurability of the catheter allows it to be adjusted between instrument deliveries. The shape memory alloy braid can be actuated to change the catheter's curvature profile, enabling the same catheter to precisely deliver different instruments to different targets without requiring multiple pre-configured catheters or instruments.
3Force
If pullwires are attached to the distal end of the catheter using traditional methods, then steering force can be applied, but stress concentration occurs and the connection may fail under physiological conditions
Solution Approach 1:
The shape memory alloy braid acts as a flexible structural element that distributes the steering forces throughout the catheter wall rather than concentrating stress at a discrete pullwire attachment point. The braid is integrated into the catheter structure, eliminating the need for separate pullwire connections and their associated stress concentration and failure risks.
4Ease of manufacture
If a single pre-shaped access catheter is used, then manufacturing is simpler, but additional repositioning is required once inside the body and the procedure becomes expensive and time consuming
Solution Approach 1:
The catheter incorporates a shape memory alloy braid that enables dynamic reconfiguration from a delivery configuration to a working configuration with the desired curvature. This allows the catheter to be delivered in a compact, simple form and then transformed in-situ to the appropriate shape, eliminating the need for multiple pre-shaped catheters and reducing procedure time and cost.
Data Source
AI summary
A steerable guide catheter includes a tip ring at a distal end and one or more pullwires configured to engage with the tip ring when put in tension, the pullwire(s) thereby subjecting the steerable guide catheter to a curving or turning force. The tip ring includes a saddle and one or more pullwire channels allowing the pullwire to be looped over the saddle such that when the pullwire is placed under tension, it abuts against the saddle of the tip ring. Some embodiments include additional catheters axially aligned within or outside of the steerable guide catheter, and include a keying feature aligning the rotation of the multiple catheters. The keys of the keying feature can be formed of a polyamide with a glass microsphere filler, and can be thermally welded to the catheter.