Electrolytic Detachment Joint with Return Electrode
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Solution Overview
Problem
The existing electrolytically detachable vaso-occlusive coils have a long and variable detachment time due to tissue impedance variations and non-optimal electrolyte environments, leading to increased procedure time and potential complications such as gas bubbling and short-circuiting.
Innovation Solution
The implementation of a pusher member with a return electrode proximal to the severable joint and an electrically conductive sheath to reduce detachment time and improve reliability, using silver chloride for enhanced electrolytic reactions, and pulsed electrical energy to minimize bubbling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the voltage is increased to reduce detachment time, then the detachment speed improves, but gas bubbling occurs which insulates the detachment zone and slows or stops the electrochemical reaction
Solution Approach 1:
A conductive gel is introduced as an intermediary substance between the sacrificial joint and the surrounding environment. The gel serves multiple functions: it maintains optimal electrolyte concentration for rapid electrochemical reaction, conducts electrical current efficiently, and prevents gas bubble formation by providing a bubble-free conductive pathway. This mediator resolves the contradiction by enabling fast detachment without the harmful gas bubbling effect.
Solution Approach 2:
The invention changes the physical and chemical parameters of the detachment environment by introducing a conductive gel with controlled viscosity, conductivity, and electrolyte concentration. These parameter changes create optimal conditions for the electrochemical reaction to proceed rapidly and uniformly, achieving fast detachment times without the side effects of gas bubble formation that occur with higher voltage alone.
2Reliability
If multiple vaso-occlusive coils are deployed, then the treatment effectiveness improves, but the total procedure time increases due to repeated long detachment times
Solution Approach 1:
The conductive gel acts as a reusable intermediary that remains in the detachment zone after each coil deployment. When subsequent coils are deployed and require detachment, the gel is already present and optimized, eliminating the need to re-establish the optimal electrolyte environment. This allows rapid sequential detachment of multiple coils, maintaining treatment effectiveness while significantly reducing total procedure time.
3Reliability
If the sacrificial joint is positioned 1 mm from the microcatheter tip to accommodate tolerance, then delivery reliability improves, but the detachment time increases due to larger tissue impedance
Solution Approach 1:
The conductive gel is introduced as a mediator that fills the space between the sacrificial joint and surrounding tissues. By positioning the joint 1 mm from the microcatheter tip (as in conventional designs) and then introducing the gel, the system maintains delivery reliability while the gel's high conductivity compensates for the increased tissue impedance, enabling rapid detachment without requiring the joint to be positioned closer to the catheter tip.
4Device complexity
If blood is used as the electrolyte, then the system is simple, but detachment time varies due to blood clotting and variations in blood constituents
Solution Approach 1:
The invention introduces a disposable conductive gel that is pre-formulated with optimal electrolyte concentration and conductive properties. Rather than relying on the variable composition of blood, the gel provides a controlled, consistent environment for the electrochemical reaction. The gel is applied locally and remains in place only for the duration of the detachment process, after which it is naturally cleared by the body's physiological processes.
Solution Approach 2:
The conductive gel changes the electrolyte parameters from variable (blood composition) to controlled (pre-formulated gel with specific conductivity, viscosity, and electrolyte concentration). This parameter change ensures consistent detachment times across different patients and procedures, eliminating the variability introduced by blood clotting and constituent variations while maintaining system simplicity through local application.
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
This configuration decreases detachment time, increases reliability and uniformity, and reduces the risk of complications by maintaining an ideal electrolytic environment and minimizing gas generation.
Implementation Method 1
Applying a positive voltage to the pusher wire via the power supply relative to the ground return causes an electrochemical reaction between the sacrificial joint and the surrounding bodily fluid (e.g., blood). As a result, the sacrificial joint will dissolve, thereby detaching the vaso-occlusive coil from the pusher wire at the selected site.
Implementation Method 2
A power supply is used to provide power to the core wire, with a conductive patch or intravenous needle located on or in the patient providing a ground return path. Applying a positive voltage to the pusher wire via the power supply relative to the ground return causes an electrochemical reaction between the sacrificial joint and the surrounding bodily fluid
Data Source
AI summary
An implant assembly (14), comprising: an elongated pusher member (18) having a proximal end (24) and a distal end (26), the pusher member including a stiffening member (80) and a first and a second electrically conductive sheath, each disposed over the stiffening member; an implantable device mounted to the distal end of the pusher member; an electrolytically severable joint (20) disposed on the pusher member, wherein the implantable device detaches from the pusher member when the severable joint is severed; a return electrode (86) disposed on the distal end of the pusher member; a first terminal (28) disposed on the proximal end of the pusher member, wherein a first electrically conductive path extends between the first terminal and the severable joint, the first electrically conductive path including the first electrically conductive sheath; and a second terminal (30) disposed on the proximal end of the pusher member, wherein a second electrically conductive path extends between the second terminal and the return electrode, the second electrically conductive path including the second electrically conductive sheath.