Lead Impedance Verification in Implantable Medical Devices
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Solution Overview
Problem
Current methods for assessing the integrity of leads in implantable medical devices, such as pacemakers and vagus nerve stimulators, are prone to inaccuracies due to interference from other resistances and capacitances, leading to potential misinterpretation of lead impedance and inappropriate device actions.
Innovation Solution
A method involving the detection of first and second impedances within predetermined ranges, with a controller determining lead condition problems and preventing therapeutic electrical signal delivery if issues are detected, utilizing multiple measurements to verify lead health and implement remedial actions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage signal discharge through resistive lead impedance is measured to assess lead integrity, then lead health can be evaluated, but measurement accuracy is compromised by interference from other resistances and capacitances in the system
Solution Approach 1:
The patent segments the impedance measurement process into multiple distinct measurement phases (first impedance measurement, second impedance measurement) and uses statistical analysis to differentiate between transient variations and genuine lead pathology. This segmentation allows the system to isolate and analyze specific impedance characteristics without being overwhelmed by concurrent system variations.
Solution Approach 2:
The patent performs preliminary impedance measurements at multiple time points before making a final determination about lead health. By conducting measurements in advance and comparing them against established criteria, the system can predict lead failures before they occur and avoid reacting to false positives from transient interference.
2Reliability
If single-point impedance measurement is used to determine lead condition, then device response time is reduced, but false readings occur leading to inappropriate device actions
Solution Approach 1:
The patent performs preliminary impedance measurements at multiple time points before making a final determination about lead health. By conducting measurements in advance and comparing them against established criteria, the system can predict lead failures before they occur and avoid reacting to false positives from transient interference.
Solution Approach 2:
The patent implements a feedback mechanism where impedance measurements are continuously monitored and compared against predetermined criteria. When measurements fall outside the criteria range, the system triggers additional verification measurements and statistical analysis before initiating any device response, creating a feedback loop that filters out false positives.
3Measurement precision
If multiple impedance measurements are performed to verify lead health, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent uses a universal statistical analysis framework that can process multiple types of impedance measurements and compare them against various predetermined criteria. This multi-functional approach allows the same measurement system to handle different lead configurations and failure modes without requiring separate specialized analysis circuits for each scenario.
Solution Approach 2:
The patent changes the measurement parameters by taking impedance readings at different time points and comparing them against different predetermined criteria ranges. By varying the measurement parameters and analysis criteria rather than adding complex hardware, the system achieves higher measurement precision through software-based statistical evaluation.
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 provides more accurate and reliable assessment of lead health, reducing false readings and ensuring appropriate device operation by using multiple parameter measurements and statistical analysis to categorize and respond to lead condition problems.
Implementation Method 1
Impedance measurements may be used to assess the integrity of the electrical leads that deliver the stimulation provided by a pulse generator. A change in the impedance across the leads that deliver the electrical pulses may be indicative of either or both of changes in a patient's body or changes in the electrical leads themselves.
Data Source
AI summary
A method, apparatus, and system for determining an adverse operational condition associated with a lead assembly in an implantable medical device used for providing a therapeutic electrical signal to a cranial nerve. A first impedance associated with the lead assembly configured to provide the therapeutic electrical signal to a cranial nerve is detected. A determination is made as to whether the first impedance is outside a first predetermined range. A second impedance is detected. The detection of the second impedance is performed within a predetermined period of time from the time of the detection of the first impedance. A determination is made as to whether the second impedance is outside a second predetermined range. If the first impedance is outside the first range and the second impedance is outside the second range, the implantable medical device is prevented from providing the therapeutic electrical signal.