Electrical Contact Junction Stability in Vaso-occlusive Coil Delivery
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Solution Overview
Problem
Current vaso-occlusive coil delivery systems face instability issues at the junction where the metallic tube is secured to the pusher wire, leading to kinking and buckling due to orthogonal and axial forces, which can damage the electrolytically severable junction and impact the detachment of the embolic coil.
Innovation Solution
A delivery wire assembly with a tapered proximal tubular portion, a core wire, and an electrical contact forming an anode for an electrolytic detachment circuit, along with a ground contact and a sleeve secured by heat lamination, to enhance the structural integrity and stability of the junction, reducing the risk of kinking and improving detachment efficiency.
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 due to kinking and buckling from orthogonal and axial forces
Solution Approach 1:
The electrical contact is divided into multiple segments: a connection collar, a metallic tube, and an insulative coating. The connection collar is secured to the pusher wire, the metallic tube is secured to the connection collar, and the insulative coating is applied to the metallic tube. This segmentation distributes mechanical stresses across multiple components rather than concentrating them at a single junction, preventing kinking and buckling while maintaining electrical conductivity through the collar and tube.
Solution Approach 2:
The electrical contact assembly uses composite materials with different properties: the connection collar and metallic tube provide electrical conductivity, the insulative coating provides electrical insulation and mechanical protection, and the pusher wire provides structural support. This composite structure combines the advantages of different materials to achieve both electrical functionality and mechanical stability under orthogonal and axial forces.
2Ease of operation
If the pusher wire is made flexible to navigate vasculature, then ease of operation improves, but structural stability worsens due to buckling under axial forces
Solution Approach 1:
The pusher wire exhibits local quality variations along its length, with different sections having different mechanical properties. The distal section near the electrolytically severable junction has enhanced structural stability to resist buckling under axial forces, while proximal sections maintain flexibility for navigating vasculature. This localized differentiation allows the wire to simultaneously achieve navigability and structural stability where needed.
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 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 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.