Asymmetric Implantable Lead Electrode Current Density Directionality
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Solution Overview
Problem
Implantable lead electrodes with uniform current density distribution often result in reduced efficiency due to inactive portions that affect current density directionality, leading to undesired stimulation and decreased amplitude at active regions, particularly in cardiac rhythm management applications.
Innovation Solution
The design incorporates an asymmetrically distributed current density in lead electrodes, with a greater conductor mass at active portions and altered surface geometry to direct current density towards target tissue, reducing undesired stimulation by optimizing the mass distribution and geometry of the electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform wall thickness is used throughout the ring-type electrode, then manufacturing simplicity is maintained, but current density directionality is compromised leading to undesired stimulation
Solution Approach 1:
The electrode transitions from uniform wall thickness to asymmetric wall thickness distribution, with thicker portions positioned to direct current toward target tissue and thinner portions at inactive regions. This asymmetric geometry creates non-uniform current density that stimulates only desired areas while avoiding harmful stimulation of surrounding tissues.
Solution Approach 2:
Different sections of the electrode are given different wall thicknesses to create locally optimized current density characteristics. The thicker sections concentrate current at active stimulation sites, while thinner sections reduce current at inactive portions, achieving spatially varying electrical properties matched to functional requirements.
2Strength
If inactive portions of the electrode are present, then lead securing and structural integrity are improved, but current density amplitude at active regions is decreased
Solution Approach 1:
The electrode structure uses asymmetric wall thickness where inactive portions have reduced thickness compared to active portions. This asymmetric design minimizes the current-blocking effect of inactive sections while maintaining structural integrity through strategically positioned thicker segments that provide mechanical strength without compromising electrical performance at active sites.
3Reliability
If greater conductor mass is concentrated at active portions, then current density directionality is improved, but manufacturing precision requirements increase
Solution Approach 1:
The electrode implements local quality variations through controlled wall thickness changes at specific angular positions around the ring. Rather than requiring complex non-uniform mass distribution throughout, the design achieves current directionality through localized thickness modifications that are more amenable to manufacturing while maintaining reliable current density directionality.
Data Source
AI summary
Lead electrodes having an asymmetrically distributed current density and methods for imparting current density directionality in lead electrodes are described. An implantable medical lead includes a lead body having a proximal section that connects to another implantable device and a distal section having a pre-biased shape configured to secure the lead to an inner wall of a body vessel. An electrode coupled to the distal section of the lead body includes a conductor mass having an asymmetrically distributed current density that imparts a directionality to one or more active portions of the electrode.