Implantable Device Noise Detection via Electrode Voltage
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Solution Overview
Problem
Implantable medical devices, such as cardiac stimulators, face interference from external electromagnetic noise that distorts cardiac and pulmonary impedance measurements, necessitating a method to detect and mitigate such noise effectively.
Innovation Solution
An implantable medical device with a voltage measuring device and a control module that calculates noise parameters based on voltage measurements over different electrode configurations, comparing these parameters to predetermined reference values to detect and manage electromagnetic noise, thereby ensuring accurate impedance measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electromagnetic noise detection is implemented using existing methods, then noise affecting low frequency cardiac sensing can be detected, but noise in the frequency spectrum of 7-10 kHz that distorts impedance measurements cannot be effectively detected
Solution Approach 1:
The patent changes the detection parameter from low frequency voltage sensing to high frequency voltage measurement specifically targeting the 7-10 kHz spectrum where impedance measurement noise occurs. The system measures voltage during impedance measurement cycles and calculates noise parameters (RMS, peak-to-peak) specifically for this frequency range, enabling detection of noise that corrupts impedance data while filtering out lower frequency cardiac signals.
2Measurement precision
If noise filtering methods are applied to remove spurious data points, then measurement quality improves, but the complexity of the device increases
Solution Approach 1:
The system performs preliminary noise detection by measuring voltage during impedance measurement cycles and calculating noise parameters before final impedance values are used. This preliminary assessment allows the system to identify noisy measurements and exclude them from analysis, improving measurement precision without requiring complex real-time filtering algorithms during critical decision-making periods.
Solution Approach 2:
The patent introduces an intermediary noise detection mechanism that measures voltage as a separate parameter during impedance measurement cycles. This voltage measurement serves as a mediator to assess noise levels independently, allowing the system to determine whether impedance measurements are valid without directly interfering with the impedance measurement process itself.
3Measurement precision
If multiple measurement vectors with different noise pick-up areas are used, then noise detection accuracy improves, but the time required for measurements increases
Solution Approach 1:
The patent merges noise detection functionality with existing impedance measurement cycles by utilizing the same electrode configurations and measurement timing. Instead of separate noise detection measurements, the system calculates noise parameters from voltage measurements taken during regular impedance measurement cycles, thereby improving noise detection accuracy without adding extra measurement time.
Data Source
AI summary
The present invention generally relates to implantable medical devices, such as pacemakers, and, in particular, to a method and an implantable medical device capable of detecting the presence of noise caused by external noise sources. Voltages and/or impedances are measured over one or several electrode configurations. Based on the measured voltages and/or impedances, noise parameters are calculated, which are compared with reference values to detect the presence of noise. In another aspect of the invention, at least two different electrode configurations with different noise pick-up areas are used in the measurement. Relations between the noise parameters of the at least two vectors are calculated and compared with reference relations to detect the presence of noise.