Catheter Flat Beam Deflection with Single Puller Wire
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Solution Overview
Problem
Existing catheters for bi-directional deflection in medical procedures face challenges such as increased component complexity, risk of puller wire failure, and inadequate support for torsional and axial loads, which can lead to reduced durability and precision in navigating varying tubular regions of the heart.
Innovation Solution
A catheter design featuring a single continuous puller wire with a U-bend and parallel segments, anchored at the distal end of a flat beam with spacers to minimize deflection force and shear stress, and a joint structure with fused brackets for enhanced torsional coupling and support, allowing for predictable on-plane bi-directional deflection and improved durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple puller wires are used for bi-directional deflection, then deflection capability is improved, but device complexity and risk of component failure increase
Solution Approach 1:
The patent combines multiple puller wires into a single continuous puller wire that loops around a pulley at the distal end of the catheter. This single wire replaces what would traditionally require multiple separate wires, thereby reducing component count and complexity while maintaining the ability to deflect the catheter tip in multiple directions. The pulley acts as the merging point where the single wire achieves the functional equivalence of multiple wires.
Solution Approach 2:
The single continuous puller wire performs multiple functions: it provides bidirectional deflection, loops around the pulley to change direction, and transmits force from the operator to the catheter tip. This multi-functional design eliminates the need for separate components for each function, reducing overall device complexity while maintaining versatility.
2Volume of moving object
If puller wires are located close to the beam, then space is saved, but large bending moments are required causing significant stress on puller wires
Solution Approach 1:
The pulley acts as an intermediary component between the puller wire and the catheter beam. By positioning the pulley at the distal end of the beam, it serves as a leverage point that amplifies the operator's input force. This mechanical advantage reduces the stress on the puller wire while still achieving effective beam deflection, resolving the conflict between space constraints and stress reduction.
Solution Approach 2:
The puller wire is configured to loop around the pulley in a spatial arrangement that optimizes force distribution. Rather than pulling parallel to the beam, the wire approaches and departs from the pulley at angles that create a more favorable moment arm, reducing the required force while maintaining compact dimensions.
3Reliability
If T-bars and crimps are used to attach puller wires, then attachment is secured, but puller wire fatigue and shear stresses increase
Solution Approach 1:
The patent extracts the problematic attachment components (T-bars and crimps) from the design. Instead of using these mechanical fasteners that create stress concentration points and fatigue risks, the system relies on the continuous loop configuration where the wire is anchored at both ends without intermediate attachment hardware. This elimination of attachment components directly reduces fatigue and shear stress on the puller wire.
Solution Approach 2:
The puller wire configuration changes from discrete segments attached with hardware to a continuous loop with smooth transitions. This parameter change in the wire geometry eliminates sharp bends and attachment points that would create stress concentrations, thereby improving durability and reducing fatigue while maintaining secure attachment at the anchor points.
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 solution enables more precise and durable bi-directional deflection with reduced component complexity, improved durability, and enhanced support for torsional and axial loads, facilitating better navigation through varying heart tubular regions while maintaining space for mapping and ablation components.
Implementation Method 1
a large bending moment is required to deflect the beam, imposing significant stress on the puller wires
Implementation Method 2
The spacers also increase durability of the puller wires by providing a geometry that allows tensile load with minimal shear stress
Implementation Method 3
each proximal segment extending along the deflection beam is guided, maintained and/or bounded to the beam at a predetermined separation distance from the beam surface by a spacer. The spacers also increase durability of the puller wires by providing a geometry that allows tensile load with minimal shear stress
Implementation Method 4
a joint structure with fused brackets for enhanced torsional coupling and support
Implementation Method 5
enhanced support for torsional and axial loads
Data Source
Figure 1
Figure 2
Figure 2A~2B
AI summary
A catheter has a deflection beam with rectangular cross-section and a single continuous puller wire for predictable on-plane bi-directional deflection. The puller wire extends through spacers on opposite sides of the beam so the puller wire is maintained a predetermined separation distance from the beam surface. Tubular structures of the catheter body and the deflectable section are fused at a joint by C-shaped brackets mounted opposite surface of the beam to form a hollow body with holes into which thermoplastic materials covering the catheter body and the deflectable section can melt to form interlocking nodes. Elongated beam stiffeners can be mounted on the beam to provide different curve and deflection geometries.