Flat-Wire Coil Shaft Structure for Flexible High-Force Delivery
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Solution Overview
Problem
Elongate medical devices, such as delivery systems for structural heart implants, require high tensile and compressive forces while maintaining flexibility and torque response, but conventional designs compromise flexibility with increased stiffness.
Innovation Solution
A shaft design featuring a flat wire coil with a higher radial height than width, providing a wider surface area for contact and improved flexibility, radial strength, and kink resistance, combined with a jacket and optional braid layer for enhanced tensile and torque strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the shaft is designed with increased tensile strength and compressive strength components, then the shaft strength is improved, but the flexibility decreases and the device becomes stiffer
Solution Approach 1:
The shaft is divided into multiple segments with different properties: a proximal segment with higher stiffness for strength and a distal segment with lower stiffness for flexibility. This segmentation allows each segment to be optimized for its specific function, resolving the contradiction between overall strength and flexibility.
Solution Approach 2:
Different portions of the shaft wall are given different compositions and structures. The proximal shaft wall uses materials and structures optimized for strength, while the distal shaft wall uses materials and structures optimized for flexibility. This local differentiation allows the shaft to simultaneously achieve both strength and flexibility requirements.
2Strength
If the shaft structure becomes stiffer to increase tensile, compression, or torque performance, then the strength is improved, but the flexibility decreases
Solution Approach 1:
The shaft is segmented into proximal and distal portions with different torsional stiffness characteristics. The proximal segment provides torque support while the distal segment maintains flexibility for navigation, allowing the shaft to achieve both torque performance and flexibility.
Solution Approach 2:
The shaft wall composition and structure are locally optimized at different positions. The proximal portion has higher torsional rigidity for torque transmission, while the distal portion has lower torsional rigidity for flexibility, enabling simultaneous achievement of torque performance and flexibility.
Data Source
AI summary
In various examples, a shaft for an elongate medical device extends along a shaft length. The shaft includes a shaft axis, an outer surface, and an inner surface. The inner surface defines an inner lumen. A liner forms the inner surface of the shaft. A coil is disposed around and outwardly from the liner. The coil is formed from a flat wire. The flat wire includes a wire width and a wire height, wherein the wire height is greater than the wire width. The wire height extends substantially radially with respect to the shaft and the wire width extends substantially longitudinally with respect to the shaft. A jacket is disposed around and outwardly from the coil. The jacket forms the outer surface of the shaft.