Magnetic Sensor EMI Detection for Implantable Cardiac Devices
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Solution Overview
Problem
Cardiac rhythm management devices face interference from extraneous electromagnetic fields (EMI) that can cause inappropriate inhibition of pacing and delivery of defibrillation shocks due to misinterpretation of magnetic noise as cardiac activity.
Innovation Solution
The implementation of a magnetic sensor within the device to detect EMI, distinguishing it from telemetry communications and correlating its onset with increased intrinsic cardiac activity, allowing the device to enter a noise reversion mode that prevents inappropriate therapy during EMI presence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If implanted leads are used for sensing cardiac electrical activity, then cardiac rhythm management function is achieved, but the leads act as antennas for extraneous electromagnetic fields causing inappropriate inhibition of pacing and delivery of defibrillation shocks
Solution Approach 1:
A magnetic sensor is introduced as an intermediary component to detect external magnetic fields before they can interfere with cardiac sensing. The magnetic sensor acts as a mediator that provides early warning of EMI presence, allowing the device to take protective actions before inappropriate pacing inhibition or defibrillation shock delivery occurs.
Solution Approach 2:
The magnetic sensor performs preliminary detection of external magnetic fields, enabling the device to anticipate and prevent EMI-related problems before they affect cardiac rhythm management. By detecting magnetic fields in advance and entering noise reversion mode proactively, the system prevents inappropriate inhibition of pacing and defibrillation shocks.
2Reliability
If a magnetic sensor is added to detect EMI, then EMI detection capability is improved, but device complexity increases
Solution Approach 1:
The magnetic sensor serves multiple functions: detecting EMI from external magnetic fields, distinguishing between telemetry communications and environmental noise, and triggering noise reversion mode. By making the sensor system multi-functional, the patent reduces the need for separate dedicated components for each function, thereby limiting the increase in device complexity while maintaining improved EMI detection capability.
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
Effectively prevents inappropriate pacing inhibition and defibrillation shocks by accurately differentiating EMI from cardiac activity, ensuring reliable operation of cardiac rhythm management devices.
Implementation Method 1
EMI is detected by using a magnetic sensor incorporated into the device. Such a sensor may be a dedicated device or may be the telemetry coil which is normally used by the device to send and receive telemetry communications via an inductive link.
Implementation Method 2
the telemetry coil which is normally used by the device to send and receive telemetry communications via an inductive link
Implementation Method 3
Cardiac rhythm management devices such as described above monitor the electrical activity of heart via one or more sensing channels so that pacing pulses or defibrillation shocks can be delivered appropriately.
Data Source
AI summary
A method and system for the detection of electromagnetic interference is disclosed in which a telemetry coil or other magnetic sensor is used to detect a magnetic signal. If a magnetic signal is determined to be a non-telemetry signal and is time-correlated with the onset of an increase in heart rate, electromagnetic interference is assumed to be present.