Double-Loop Catheter Deflection With a Single Puller Wire
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Solution Overview
Problem
Existing electrode catheters face issues with bi-directional deflection accuracy due to bending and shearing stresses on puller wires, skewing, off-plane deflection, and micro-movements between the support member and non-conductive cover, which affect the precision of mapping and ablation procedures.
Innovation Solution
A catheter design featuring a single continuous puller wire with off-axis lumens, compression coils, and a non-conductive cover with a tight fit to minimize shear stress, along with a support member anchored by a serrated proximal end and adhesive volume to enhance stability and predictability of deflection, and a location sensor protected from torsional forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single continuous puller wire is used for bi-directional deflection, then device complexity is reduced, but deflection accuracy deteriorates due to bending and shearing stresses
Solution Approach 1:
The single continuous puller wire is segmented into functional zones: a mid-portion that straddles the lumens and experiences minimal stress, and proximal end portions that extend into the lumens for actuation. This segmentation allows the wire to handle bi-directional forces while maintaining deflection accuracy by isolating the critical mid-portion from bending and shearing stresses.
Solution Approach 2:
Washers are introduced as intermediary components between the puller wire and the distal end of the deflectable section. These washers provide bearing surfaces that reduce bending and shearing stresses on the wire, thereby maintaining deflection accuracy while using a single continuous wire structure.
2Strength
If the puller wire distal end is anchored by crimped ferrule or T-bar adhesive, then anchoring strength is improved, but the wire is subjected to combined bending and shear stresses causing skewing
Solution Approach 1:
The harmful anchoring methods (crimped ferrule and T-bar adhesive) are completely removed from the design. Instead, the puller wire is configured to pass through the deflectable section without traditional anchoring, eliminating the source of bending and shear stresses that cause skewing and off-plane deflection.
Solution Approach 2:
Instead of anchoring the wire to the distal end structure, the design inverts the approach by having the wire pass through off-axis lumens and use washers for stress distribution. The wire is not rigidly fixed but rather guided through the structure, which prevents the development of bending and shear stresses.
3Ease of manufacture
If the non-conductive cover has a loose fit with the support member, then ease of assembly is improved, but micro-movements occur reducing mapping precision
Solution Approach 1:
The fit between the non-conductive cover and support member is changed from a loose fit to a tight interference fit. This parameter change eliminates micro-movements between the components, ensuring mapping precision while still allowing for practical assembly through the interference fit mechanism.
4Ease of manufacture
If the support member is not firmly anchored, then ease of assembly is improved, but stability deteriorates under repeated contact forces
Solution Approach 1:
The anchoring solution uses a composite approach combining mechanical features (serrations on the support member) with chemical bonding (adhesive volume). This composite anchoring method provides firm stabilization under repeated contact forces while maintaining relative ease of assembly through the adhesive process.
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 design provides predictable, on-plane bi-directional deflection with reduced skewing and micro-movements, ensuring accurate mapping and ablation by minimizing stress on components and maintaining precise positioning of the distal assembly.
Implementation Method 1
A support member having shape-memory is disposed within at least the main region of the mapping assembly
Implementation Method 2
The first lumen is sized to provide a tight or interference fit with the support member to minimize free play and micro-movements between the cover and the support member
Implementation Method 3
the deflection mechanism draws on the puller wire proximally to deflect the catheter toward that side
Data Source
AI summary
A catheter has a distal assembly with at least one loop with ring electrodes. A single continuous puller wire for bidirectional deflection is pre-bent into two long portions and a U-shape bend therebetween. The U-shape bend is anchored at a distal end of a deflectable section which is reinforced by at least one washer having at least two holes, each hole axially aligned with a respective lumen in the deflectable section. Each hole is centered with a lumen so that each puller wire portion therethrough is straight and subjected to tensile force only. A proximal end of the support member is flattened and serrated to provide a better bonding to the distal end of the deflectable section.