Implantable Lead Helical Conductor Design
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Solution Overview
Problem
Conventional implantable medical leads face issues with reliability due to connector failures, increased tissue attachment, and difficulty in extraction, particularly in regions with exposed electrodes, which affects electrical performance and leads to complications like infection or dislodgement.
Innovation Solution
The development of an implantable lead with a helically-wound conductor design using multi-stranded wire and fluoropolymer insulation, eliminating the need for discrete connectors and minimizing tissue ingrowth through a continuous conductor-to-electrode configuration, while maintaining flexibility, fatigue resistance, and a small diameter profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If discrete connectors or junctions are used between conductors and electrodes, then electrical connection is achieved, but reliability decreases due to points of failure and lead diameter increases making extraction difficult
Solution Approach 1:
The patent merges the conductor and electrode into a single continuous element. The helically-wound conductor extends from the proximal connector region to the distal end where it forms the electrode, eliminating the need for discrete connectors or junctions. This integration removes potential failure points and simplifies the overall structure while maintaining electrical functionality.
Solution Approach 2:
The patent extracts the discrete connector component from the lead structure. By eliminating the separate connector and its associated junction, the design removes the interface that creates reliability issues and increased diameter. The conductor transitions directly into the electrode without requiring additional connecting elements.
2Reliability
If exposed coil electrodes are used, then electrical contact with tissue is achieved, but tissue ingrowth and anchoring occur making lead extraction difficult
Solution Approach 1:
The patent applies a thin fluoropolymer coating over the helically-wound conductor electrode. This thin film provides a barrier that prevents tissue ingrowth and anchoring while maintaining electrical functionality. The coating allows the lead to be extracted more easily by reducing tissue attachment, yet still permits effective electrical contact through the porous structure of the fluoropolymer material.
Solution Approach 2:
The fluoropolymer coating is provided in a porous form that allows bodily fluids to penetrate through it. This porosity enables electrical conduction through the coating while the coating itself remains electrically non-conductive, preventing tissue ingrowth. The porous structure facilitates fluid penetration for electrical contact while blocking tissue cell infiltration.
3Length of moving object
If lead diameter is reduced for smaller profile, then insertion ease is improved, but abrasion and crush resistance decrease
Solution Approach 1:
The patent employs composite material structures throughout the lead construction. Multiple layers including fluoropolymer insulation, porous coatings, and helically-wound conductors are combined to achieve optimal properties. The fluoropolymer provides chemical inertness and electrical functionality, while the helical wire structure provides mechanical strength. This composite approach allows small diameter while maintaining resistance to abrasion and crush forces.
Solution Approach 2:
The patent uses a helically-wound conductor design that provides inherent flexibility and mechanical strength. The helical configuration allows the conductor to flex and bend without breaking, providing fatigue resistance and flexibility despite the small lead diameter. The curved, spiral structure distributes mechanical stresses more effectively than a straight wire, enhancing abrasion and crush resistance in a compact form.
Data Source
AI summary
A highly flexible implantable lead that offers improved flexibility, fatigue life and fatigue and abrasion resistance improved reliability, effective electrode tissue contact with a small diameter and low risk of tissue damage during extraction. In one embodiment the lead is provided with both defibrillation electrodes and pacing/sensing electrodes. For defibrillation/pacing leads, the lead diameter may be as small as six French or smaller. The construction utilizes helically wound conductors. For leads incorporating multiple separate conductors, many of the helically wound conductors are arranged in a multi-filar relationship. Preferably, each conductor is a length of wire that is uninsulated at about the middle of its length to create an electrode, wherein the conductor is folded in half at about the middle of the length to create first and second length segments that constitute parallel conductors.