Steerable Sheath Pull Wire Layout for Torque Without Whipping
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Solution Overview
Problem
Steerable introducers experience issues with pull wires breaking or whipping due to stored energy when torque is applied with the sheath in a deflected position, leading to unpredictable movements and potential failure.
Innovation Solution
The steerable sheath design includes pull wires configured in helical paths along the non-deflectable portion and straight paths along the deflectable portion, combined with electrode wires wrapped in varying wind patterns and reflowed polymeric layers to manage torque application and reduce energy storage, ensuring smooth response without breaking or whipping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If pull wires are configured in straight lines from proximal to distal end of the sheath, then the steerable sheath can be effectively steered by pulling the wires, but the pull wires are prone to breaking or whipping when torque is applied due to stored energy
Solution Approach 1:
The pull wires are configured in helical paths around the circumference of the inner liner in the non-deflectable portion, transforming the straight wire arrangement into a curved/helical one. This curvature allows the wires to accommodate torque application without storing excessive energy, preventing whipping and breaking while maintaining steerability through the straight path configuration in the deflectable portion
2Ease of operation
If pull wires extend in straight paths through the deflectable portion, then steering control is maintained, but torque application causes unpredictable movements and potential wire failure
Solution Approach 1:
The sheath is divided into two distinct portions: a non-deflectable portion with helical pull wire paths and a deflectable portion with straight pull wire paths. This segmentation allows each portion to serve its specific function - the non-deflectable portion manages torque without storing energy, while the deflectable portion maintains steering control, thereby eliminating whipping and unpredictable movements
Data Source
AI summary
A steerable sheath includes an inner liner extending from a proximal to a distal end of the steerable sheath. The inner liner includes a non-deflectable portion and a deflectable portion. The steerable sheath includes a first pull wire positioned along a first helical path around the circumference of the inner liner from a proximal to a distal end of the non-deflectable portion and along a first straight path from a proximal to a distal end of the deflectable portion. The steerable sheath includes a second pull wire positioned along a second helical path around the circumference of the inner liner from the proximal to the distal end of the non-deflectable portion and along a second straight path from the proximal to the distal end of the deflectable portion. The steerable sheath may also include electrode wires present in a helical or spiral pattern around the circumference of the steerable sheath.