Implantable lead bandstop filter employing an inductive coil with parasitic capacitance to enhance MRI compatability of active medical devices

Abstract

A medical lead system includes at least one bandstop filter for attenuating current flow through the lead across a range of frequencies. The bandstop filter has an overall circuit Q wherein the resultant 3 dB bandwidth is at least 10 kHz. The values of capacitance and inductance of the bandstop filter are selected such that the bandstop filter is resonant at a selected center frequency or range of frequencies. Preferably, the bandstop filter has an overall circuit Q wherein the resultant 10 dB bandwidth is at least 10 kHz. Such bandstop filters are backwards compatible with known implantable deployment systems and extraction systems.

Description

FIELD OF THE INVENTION[0001]This invention relates generally to novel inductive coil-parasitic capacitance bandstop filter assemblies, particularly of the type used in the implantable leads of active medical devices (AMDs) such as cardiac pacemakers, cardioverter defibrillators, neurostimulators, externally worn Holter monitors and the like, which decouple lead wires and / or electronic components of the medical device from undesirable electromagnetic interference (EMI) signals at a selected center frequency or range of frequencies, such as the RF pulsed fields of Magnetic Resonance Imaging (MRI) equipment.BACKGROUND OF THE INVENTION[0002]Compatibility of cardiac pacemakers, implantable defibrillators and other types of active implantable medical devices with magnetic resonance imaging (MRI) and other types of hospital diagnostic equipment has become a major issue. If one goes to the websites of the major cardiac pacemaker manufacturers in the United States, which include St. Jude Med...

AI Technical Summary

Benefits of technology

[0030]The effect of an MRI system on the function of pacemakers, ICDs and neurostimulators depends on various factors, including the strength of the static magnetic field, the pulse sequence (gradient and RF field used), the anatomic region being imaged, lead length and trajectory, and many other factors. Further complicating this is the fact that each patient's condition and physiology is different and each manufacturer's pacemaker and ICD designs also are designed and behave differently. Most experts still conclude that MRI for the pacemaker patient should not be considered safe. Paradoxically, this also does not mean that the patient should not receive MRI. The physician must make an evaluation given the pacemaker patien

Problems solved by technology

It is also well known that when the bandstop filter is at its resonant frequency, it will present a very high impedance.

However, a ma

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