Multiplexer for selection of an MRI compatible band stop filter or switch placed in series with a particular therapy electrode of an active implantable medical device

Abstract

An MRI-compatible electronic medical therapy system includes an active medical device connected to a plurality of electrodes. A multiplexer circuit includes at least one circuit protection device in electrical series with the electrodes and the medical device. The circuit protection device can be in the form of a switch or a band stop filter. The circuit protection device is adapted to permit current flow therethrough during normal medical device related therapy, but substantially prevent current flow therethrough in the presence of an induced electromagnetic field.

Description

BACKGROUND OF THE INVENTION[0001]This invention relates generally to electronic switches and switch assemblies adapted for use in active implantable medical devices (AIMDs) such as cardiac pacemakers, cardioverter defibrillators, neurostimulators and the like. The normally closed electronic switch is designed to be selectively open just prior to and during exposure of the medical device to diagnostic, therapy, electrocautery surgical procedures, or imaging such as magnetic resonance imaging (MRI). Disconnecting a distal tip electrode(s), by opening an electronic switch eliminates the possibility that undesirable RF currents could overheat said distal electrode and undesirably flow into body tissue thereby creating the potential for tissue damage (necrosis). For MRI imaging, opening the electronic switch eliminates problems associated with low frequency gradient fields as well as high frequency pulsed RF fields. The present invention is also applicable to a wide range of external med...

AI Technical Summary

Benefits of technology

The present invention is about electronic switches that can be used to prevent current from flowing through medical devices, such as pacemakers, when they are exposed to MRI machines or other medical equipment that generates electromagnetic fields. The switches are placed at the distal tip of the medical device or along its circuitry to stop RF currents from flowing through the device and potentially harming the patient. The switches can also reduce EMI or RF currents that may interfere with the device's sensitive electronic circuits. The invention is useful for a wide range of implantable and external medical devices, including deep brain stimulators, spinal cord stimulators, drug pumps, and more. The switches can be a micro-electromechanical system (MEMS) switch or a band stop filter.

Problems solved by technology

This stops the problems associated with overheating of lead wires, tissue damage and excessive currents or temperatures, and also the potential for gradient field capture of the heart which can lead to dangerous arrhythmias.

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