Implantable Lead Shield Geometry for Targeted Cardiac Stimulation

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Solution Overview

Problem

Implantable medical leads deliver electrical therapy that stimulates unintended extracardiac tissue, requiring higher energy levels and potentially damaging nearby nerves or sensory/motor nerves, leading to inefficient power consumption and reduced ICD service life.

Innovation Solution

The use of expandable shields on implantable medical leads to impede the electric field away from the heart, directing it towards the intended cardiac tissue, thereby reducing the likelihood of stimulating extracardiac tissue and allowing lower energy levels for therapy delivery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If electromagnetic shields are added to reduce RF interference, then electromagnetic compatibility is improved, but lead flexibility deteriorates due to shield rigidity

Engineering Contradiction:

Improveelectromagnetic compatibilityVSAvoidlead flexibility

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The lead is divided into multiple flexible segments or sections, each containing conductors that can bend independently. This segmentation allows the lead to maintain flexibility while the collective structure provides electromagnetic shielding through the distributed conductive elements and insulating layers.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The lead employs composite construction combining conductive shielding materials with flexible insulating materials. The conductors are surrounded by flexible insulating layers, creating a composite structure that provides electromagnetic compatibility while maintaining overall lead flexibility through the compliant insulating material.

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If multiple conductors are bundled together for signal transmission, then functionality is improved, but susceptibility to RF interference worsens

Engineering Contradiction:

Improvesignal transmission capabilityVSAvoidRF interference susceptibility

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

Flexible insulating layers are introduced as intermediary materials between adjacent conductors. These insulating layers act as mediators that electrically isolate the conductors from each other, preventing RF interference coupling between signals while allowing each conductor to transmit its designated signal independently.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

Thin flexible insulating films or layers surround each conductor or group of conductors. These flexible shells provide electromagnetic isolation between conductors, reducing RF interference susceptibility, while their flexibility maintains the overall lead's ability to bend and conform to implantation sites.

Inventive Principle:

Principle #30Flexible shells and thin films

3Reliability

If conductor insulation is increased to prevent interference, then electrical isolation is improved, but lead flexibility deteriorates

Engineering Contradiction:

Improveelectrical isolationVSAvoidlead flexibility

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The insulating material parameters are optimized to achieve the minimum necessary thickness for adequate electrical isolation while maintaining flexibility. By carefully controlling the dielectric properties and thickness of the insulating layers, the design achieves sufficient electrical isolation without excessive insulation that would compromise lead flexibility.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Thin flexible insulating films are applied to conductors rather than thick rigid insulation. These thin films provide adequate electrical isolation for the application while their thin profile and flexible nature preserve the lead's ability to bend and flex during implantation and operation.

Inventive Principle:

Principle #30Flexible shells and thin films

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 shields reduce the likelihood of stimulating unintended tissues, lower energy consumption, and extend the service life of implantable devices by directing the electric field effectively towards the heart, thus optimizing therapy delivery.

Implementation Method 1

A flexible insulating layer of Parylene C is disposed between adjacent conductors

Methodology Applied

Scientific EffectDielectric: Dielectric

Data Source

PatentEP4489843B1Implantable medical lead with shield

Publication Date: 2026.04.29 MEDTRONIC INC

Figure 1A
Figure 1B
Figure 1C

AI summary

An example implantable medical lead includes a first defibrillation electrode and a second, defibrillation electrode, the first and second, defibrillation electrodes configured to deliver first electrical therapy. Tire implantable medical lead also includes a. pace electrode disposed longitudinally between the first defibrillation electrode and die second defibrillation electrode, the pace electrode configured to deliver second electrical therapy comprising pacing pulses. The implantable medical lead further includes a shield disposed over a portion of an outer surface of the pace electrode and extending laterally away from the pace electrode, wherein the shield comprises an asymmetric shape about a longitudinal axis of the shield, wherein die shield is configured to impede an electric field of at least one of the first and second electrical therapies in a direction away from a. heart of the patient.