Dynamic Lead Condition Detection in Implantable Medical Devices

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Solution Overview

Problem

Current implantable medical devices (IMDs) face challenges in accurately detecting intermittent lead failures, which can result in position-dependent loss of therapy due to lead impedance changes, and frequent impedance measurements can shorten battery life.

Innovation Solution

A method and system for dynamic lead condition assessment using a pulsed therapeutic electrical signal with feedback signals to determine voltage thresholds, allowing for continuous monitoring of lead impedance and detection of intermittent lead problems, including breaks or shorts, while minimizing energy consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If frequent impedance measurements are performed to detect intermittent lead failures, then detection reliability is improved, but energy consumption increases and battery life decreases

Engineering Contradiction:

Improvelead failure detection reliabilityVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent implements periodic impedance measurements at scheduled intervals rather than continuous monitoring, allowing the system to detect lead failures while conserving battery energy through controlled measurement frequency

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system uses existing therapeutic pulse signals to perform impedance measurements without requiring separate dedicated measurement signals, thereby utilizing already-present electrical activity for dual purposes of therapy and diagnostics

Inventive Principle:

Principle #25Self-service

2Device complexity

If traditional RC time-constant method is used for impedance measurement, then measurement process is simple, but measurement precision deteriorates due to inaccuracies from other resistances and capacitances in the system

Engineering Contradiction:

Improvemeasurement process complexityVSAvoidimpedance measurement precision

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent extracts and isolates the lead impedance component from the total system impedance by using differential measurement techniques that subtract out contributions from other circuit elements, body tissues, and capacitive components

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The system introduces known test signal characteristics as intermediaries to separate the lead impedance measurement from other system variables, using controlled current pulses with defined parameters to isolate the lead's electrical properties

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If voltage-controlled output is used in IMDs, then delivery control is simplified, but detection of lead condition problems becomes more difficult due to variable impedance effects

Engineering Contradiction:

Improvedelivery control simplicityVSAvoidlead condition detection difficulty

Core Design Contradiction:

Ease of operationVSDifficulty of detecting and measuring

Solution Approach 1:

The system incorporates feedback mechanisms that monitor the actual voltage and current delivered during therapeutic pulses, comparing measured values against expected values to detect deviations indicating lead problems

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The voltage-controlled output circuit serves dual functions: delivering therapeutic electrical pulses and simultaneously performing impedance measurements for lead condition monitoring through the same hardware pathways

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 approach enables the early detection of intermittent lead failures, correlates causes with patient activities or physiological parameters, and reduces battery drain by focusing on continuous, rather than periodic, impedance measurements.

Implementation Method 1

a lead assembly in an implantable medical device for providing a controlled current therapeutic electrical signal to a cranial nerve

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

Each the feedback signal comprises a voltage signal associated with the lead assembly for a pulse in the pulsed therapeutic electrical signal

Methodology Applied

Scientific EffectOhm's law: Ohm's Law

Data Source

PatentUS8868203B2Dynamic lead condition detection for an implantable medical device

Publication Date: 2014.10.21 LIVANOVA USA INC

AI summary

A method, apparatus, and system for perform dynamic detection of a lead condition associated with a lead assembly in an implantable medical device that provides a controlled current therapeutic electrical signal to a cranial nerve. A pulsed therapeutic electrical signal is provided to a portion of a patient's body. A multiplicity of feedback signals is provided. Each the signal in the multiplicity comprises a voltage signal associated with the lead assembly for a pulse in the pulsed therapeutic electrical signal. For each the feedback signal, a determination is made as to whether the voltage signal is below a predetermined threshold to create a multiplicity of voltage signal comparison results. A determination is made as to whether or not a lead condition problem exists based upon the multiplicity of voltage signal comparison results.