Electrical Contact Junction Stability in Occlusive Device Delivery
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Solution Overview
Problem
Current vaso-occlusive coil delivery systems face instability at the junction where the metallic tube is secured to the pusher wire, leading to kinking and buckling under orthogonal and axial forces, which can damage the junction and impact the detachment of the embolic coil by electrolysis.
Innovation Solution
A delivery wire assembly with a tapered proximal tubular portion, a core wire, and an electrical contact forming an anode for electrolytic detachment, along with a ground contact and a sleeve secured by heat lamination, enhances the structural integrity and stability of the junction, reducing the risk of kinking and improving detachment reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metallic tube is secured to the pusher wire to form an electrical contact, then electrical conductivity is achieved, but mechanical stability deteriorates causing kinking and buckling
Solution Approach 1:
The electrical contact is divided into multiple segments: a collar portion that interfaces with the pusher wire and a shaft portion that provides structural support. This segmentation allows each part to optimize its function - the collar for electrical contact and the shaft for mechanical stability, preventing kinking and buckling while maintaining detachment reliability.
Solution Approach 2:
The electrical contact features localized structural enhancements including the collar portion with increased diameter for stability, and the shaft portion with specific dimensional ratios. These local quality variations provide targeted mechanical support where needed while maintaining electrical conductivity throughout the structure, resolving the contradiction between stability and conductivity.
2Ease of operation
If the pusher wire is made flexible to navigate vasculature, then ease of operation improves, but structural integrity worsens leading to kinking
Solution Approach 1:
The pusher wire is constructed with a flexible yet structurally sound design that can navigate the vasculature without kinking. The wire's flexibility allows it to follow vascular pathways while its engineered structure prevents buckling and kinking under axial and orthogonal forces, maintaining both ease of operation and structural integrity.
Solution Approach 2:
The delivery system uses composite construction combining flexible materials for navigation with reinforcing elements that prevent kinking. This composite approach allows the pusher wire to be sufficiently flexible for vascular navigation while maintaining the strength needed to resist kinking and buckling forces.
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 provides improved mechanical stability and reliable detachment of the occlusive coil by reducing stress concentrations and preventing buckling, ensuring effective deployment of the vaso-occlusive device in the vasculature.
Implementation Method 1
An electrolytically severable junction, which is a small exposed section or detachment zone located along a distal end portion of the pusher wire. The detachment zone is typically made of stainless steel and is located just proximal of the vaso-occlusive device. An electrolytically severable junction is susceptible to electrolysis and disintegrates when the pusher wire is electrically charged in the presence of an ionic solution, such as blood or other bodily fluids.
Implementation Method 2
The delivery wire assembly also includes a sleeve disposed around at least a portion of the delivery wire conduit. The sleeve is secured to the delivery wire conduit by heat lamination.
Data Source
AI summary
A delivery wire assembly for delivery of an occlusive device to a location in a patient's vasculature includes a delivery wire conduit having a proximal tubular portion coupled to a distal coil portion, the respective tubular and coil portions defining a conduit lumen. A core wire is disposed in the conduit lumen and having a distal end coupled to an occlusive device, wherein an elongate electrical contact body at least partially seated in the conduit lumen and coupled to a proximal end of the core wire, the electrical contact body and the proximal tubular portion forming a junction. A coil collar is disposed around the electrical contact body near the junction.