IMD Charging Thermal Dose Tracking After Interruptions

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Solution Overview

Problem

Conventional methods for monitoring thermal dose during the charging of implantable medical devices (IMDs) are inadequate, failing to account for unintended interruptions, which can lead to inaccurate thermal dose calculations and potential tissue damage.

Innovation Solution

A control system that determines the cumulative thermal dose by measuring tissue temperature, continues its calculation after interruptions if certain conditions are met, and adjusts charging based on predefined thresholds to ensure patient safety and comfort.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the charging process is interrupted and restarted, then the charging can be resumed, but the thermal dose calculation becomes inaccurate leading to potential tissue damage

Engineering Contradiction:
Improvethermal dose calculation accuracyVSAvoidcharging process continuity
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The system performs preliminary actions by storing interruption data (timestamp, cumulative thermal dose at interruption, temperature) before the interruption occurs. When charging resumes, this pre-stored information is used to continue the thermal dose calculation accurately without resetting, thus maintaining calculation accuracy while allowing charging continuity.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system implements feedback by continuously monitoring charging status, temperature, and thermal dose accumulation. Upon interruption and resumption, the system uses feedback from stored interruption parameters to adjust and continue the thermal dose calculation, ensuring accuracy is maintained despite the interruption-restart cycle.

Inventive Principle:
Principle #23Feedback

2Object-affected harmful factors

If the cumulative thermal dose is continuously monitored without reset, then tissue safety is improved, but the system complexity increases

Engineering Contradiction:
Improvetissue thermal damageVSAvoidcontrol system complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The system performs preliminary action by storing critical thermal dose and temperature data before interruption occurs. This pre-stored information allows the system to continue monitoring cumulative thermal dose accurately without requiring complex continuous monitoring mechanisms throughout interruptions, thus reducing overall system complexity while maintaining safety.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system applies discarding and recovering by temporarily storing (recovering) thermal dose and temperature data during interruption, then discarding the need for complex continuous monitoring during the interruption period. Upon resumption, the stored data is recovered and used to continue the thermal dose calculation, simplifying the monitoring system while ensuring tissue safety.

Inventive Principle:
Principle #34Discarding and recovering

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 system accurately monitors thermal dose history, reducing tissue damage and discomfort by optimizing charging processes, even with unintended interruptions.

Implementation Method 1

eddy currents are usually induced in metal parts of the IMD, such as an Implantable Pulse Generator (IPG), causing the metal parts, the IPG and/or the IMD to heat up

Methodology Applied
Scientific EffectEddy currents: Eddy Currents

Implementation Method 2

eddy currents are usually induced in metal parts of the IMD, such as an Implantable Pulse Generator (IPG), causing the metal parts, the IPG and/or the IMD to heat up

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 3

CEM43 may be calculated to provide for monitoring of an amount of a heat impact of a patient's tissue during a charging process

Methodology Applied
Scientific EffectThermal dose calculation:

Data Source

PatentEP4583966B1Thermal dose calculation and protection in an implantable medical device
Publication Date: 2026.04.01 BIOTRONIK SE & CO KG
  • EP4583966B1 patent drawingFigure 1~2
  • EP4583966B1 patent drawingFigure 3~4
  • EP4583966B1 patent drawingFigure 5

AI summary

The present invention relates to control system (1) for controlling a charging process of an implantable medical device, IMD, for a patient, the control system (1) comprising: means for determining a temperature (10) of a tissue of a patient; a control unit (20) configured to determine a cumulative thermal dose of the patient based on the determined temperature; wherein the control unit (20) is configured to continue, after an interruption of the charging process and upon resumption of the charging process, the determination of the cumulative thermal dose based on one or more predefined conditions, wherein the control unit (20) is configured to reset the determined cumulative thermal dose when a time span from interruption is greater than a time limit and/or when a measured temperature is lower than a temperature limit. The present invention is further directed to a system comprising such a control system, to a method and a corresponding computer program.