Deflectable Catheter Bonded Center Strut Torque Control
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Solution Overview
Problem
Existing steerable catheters face challenges in accurately translating longitudinal motion of pull wires into uniform on-plane tip deflection due to complex manufacturing processes and varying cross-sectional area moments of inertia during tip deflection, leading to non-uniform torque and deflection forces.
Innovation Solution
A bidirectional steerable catheter with a composite tip structure featuring a thermally bonded center strut and elastomeric tube, creating an inseparable composite structure that maximizes internal volume and torsional rigidity while minimizing outer diameter, allowing for uniform on-plane deflection and constant torque and deflection forces through a unified high-performance composite structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a complex multi-component tip structure is used to achieve steerability, then the catheter can be deflected, but the manufacturing process becomes complex and time-consuming
Solution Approach 1:
The patent merges the center strut and elastomeric tube into a single integrated composite structure where the strut is thermally bonded within the tube. This consolidation reduces the number of separate components and assembly steps while maintaining the steerable function through the pull wire mechanism.
Solution Approach 2:
The invention uses a composite structure combining a rigid center strut made of superelastic alloy (such as Nitinol) with a flexible elastomeric tube. This composite material approach allows the structure to provide both steerable rigidity and flexible deflection characteristics, simplifying the overall design while maintaining operational performance.
2Length of stationary object
If the catheter tip diameter is reduced to improve access, then the working volume decreases, but the torsional rigidity and open internal volume become compromised
Solution Approach 1:
The patent applies local quality by concentrating structural reinforcement at specific locations. The center strut is positioned to provide localized torsional rigidity where needed for steerability, while the elastomeric tube maintains flexibility and open volume in other regions. This localized reinforcement allows small diameter with adequate working volume.
Solution Approach 2:
The composite structure of the center strut bonded within the elastomeric tube creates a space-efficient design. The strut provides torsional rigidity without requiring a large outer diameter, while the elastomeric material maintains flexibility and preserves internal volume for working elements.
3Adaptability or versatility
If varying cross-sectional area moments of inertia are used during tip deflection, then the catheter can deflect in different directions, but non-uniform torque and deflection forces result
Solution Approach 1:
The patent uses local quality by creating asymmetric cross-sectional geometry in the deflectable tip section. The center strut is positioned offset from the central axis, creating different area moments of inertia in different directions. This allows the tip to deflect uniformly in the plane of the strut while maintaining adaptability for bidirectional control through pull wire configuration.
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 composite catheter tip design provides consistent and precise on-plane deflection characteristics, maximizing the working volume for wiring and sensors, and reducing catheter tip diameter, thereby improving the accuracy and efficiency of medical procedures.
Implementation Method 1
The center strut is thermally bonded to an interior of the elastomeric tube
Data Source
AI summary
A catheter for diagnosing or treating the vessels found within a body or body space includes a center strut that is bonded, preferably thermally, along its longitudinal axis with the thermoplastic tubular member within which it is housed. The tubular member preferably has three layers: an inner layer, a braided layer and an outer layer. The composite catheter is made using a process in which two half-cylinder shaped mandrels are placed on each side of the center strut while the strut is heated in order to cause the thermal bonding. The bonded center strut provides in-plane deflection and improved transfer of torque to the tip of the catheter.