Braided Implantable Lead Conductor Spacing

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Solution Overview

Problem

Implantable medical leads with multiple conductors face issues with flex life and conductor crossing due to their small size and flexible nature, which affects their durability and ease of delivery in medical applications.

Innovation Solution

The use of a braided structure combining insulated conductor strands and polymer strands, where the conductors and polymer strands are helically wound in opposite directions to prevent direct crossing and enhance flex life, maintaining a stable configuration within the lead body.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple conductors are arranged in a straight or coiled cable configuration, then the lead can accommodate multiple electrical conductors, but the conductors float and cross each other reducing flex life

Engineering Contradiction:

Improveflex lifeVSAvoidconductor configuration stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The lead cable is segmented into multiple independent conductor elements (typically 7x7 stranded conductors) that are individually insulated and organized within separate segments or groups. This segmentation prevents the conductors from floating and crossing each other while maintaining flexibility, as each segmented section maintains relative conductor positions during flexing.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Multiple conductor elements are nested within each other in a hierarchical structure, with individual conductors nested within insulated jackets, which are then nested within the lead body tubing. This nested arrangement constrains conductor movement and prevents crossing while maintaining a compact, flexible configuration that accommodates multiple electrical pathways.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Volume of moving object

If the lead is made smaller in cross section, then the lead profile is less intrusive and easier to deliver, but the conductor flex life is reduced

Engineering Contradiction:

Improvelead cross section sizeVSAvoidconductor flex life

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The lead employs flexible insulating shells and thin-film conductor constructions (such as 7x7 stranded wire configurations) that maintain electrical integrity while accommodating small cross-sectional dimensions. These flexible shell structures protect the conductors without adding excessive bulk, enabling small profile leads to achieve adequate flex life through optimized insulation thickness and conductor strand configuration.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The lead utilizes composite material constructions combining multiple materials with complementary properties: flexible polymer insulation materials, stranded metal conductors with high fatigue resistance, and potentially reinforcing elements. This composite approach allows the lead to achieve small cross-section while maintaining conductor flex life through the synergistic properties of different materials optimized for their specific functions.

Inventive Principle:

Principle #40Composite materials

3Force

If a stylet or stiffening member is inserted, then the lead gains pushability, but the lead becomes stiffer affecting patient comfort

Engineering Contradiction:

Improvelead pushabilityVSAvoidlead stiffness

Core Design Contradiction:

ForceVSStrength

Solution Approach 1:

The lead employs a dynamic stiffening system where the stylet or stiffening member can be inserted or removed as needed during delivery and implantation procedures. The lead body itself is designed with intermediate stiffness through construction features such as braided reinforcement or specific polymer formulations, providing adequate pushability during insertion while maintaining patient comfort during long-term implantation when the stylet is removed.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The stylet or stiffening member is inserted preliminarily during the delivery procedure to provide temporary pushability and rigidity for navigation through the body. Once the lead is positioned at the target site, the stylet is removed, leaving the lead in its flexible implantable state. This preliminary action of inserting the stiffening member only when needed resolves the contradiction between delivery requirements and patient comfort.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS8160719B2Braided electrical lead

Publication Date: 2012.04.17 CIRTEC MEDICAL CORP

AI summary

An implantable electrical lead having a plurality of insulated conductor strands and a plurality of non-conductor strands braided together to maintain the spacing of the conductors from each other to prevent the crossing of the insulated conductor strands. The non-conductor strands are often polymeric strands. In some leads, the conductor strands and non-conductor strands are braided in opposite clockwise directions from each other. The conductor strands may travel adjacent each other in a clockwise direction, crossing non-conductors alternately over then under, with the immediately adjacent conductor strand doing the same but being out of phase. A diamond braid pattern is used in some embodiments. Braids may be formed over a removable mandrel, or a non-removable shaft or tube. Braiding can provide a structure which maintains its configuration after removal from a mandrel without requiring undue stress application to the strands.