Electromagnetic interference immune tissue invasive system

• US 20020133208A1
• Filed: 02/19/2002
• Published: 09/19/2002
• Est. Priority Date: 02/20/2001
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Biophan Technologies Incorporated
• Inventors: Connelly, Patrick R.
• Granted Patent: US 6,819,954 B2
• Time in Patent Office: Days
• US Class Current: 607/36
• CPC Class Codes: A61N 1/056 Transvascular endocardial electrode systems
• CPC Class Codes: A61N 1/086 Magnetic resonance imaging [MRI] compatible leads
• CPC Class Codes: A61N 1/3718 Monitoring of or protection against external electromagnetic fields or currents
• CPC Class Codes: A61N 1/37512 Pacemakers
• CPC Class Codes: G01R 33/285 Invasive instruments, e.g. catheters or biopsy needles, specially adapted for tracking, guiding or visualization by NMR
• CPC Class Codes: G01R 33/288 Provisions within MR facilities for enhancing safety during MR, e.g. reduction of the specific absorption rate [SAR], detection of ferromagnetic objects in the scanner room

Abstract

An electromagnetic immune tissue invasive system includes a primary device housing. The primary device housing having a control circuit therein. A shielding is formed around the primary device housing to shield the primary device housing and any circuits therein from electromagnetic interference. A lead system transmits and receives signals between the primary device housing. The lead system is either a fiber optic system or an electrically shielded electrical lead system.

Claims

1. A cardiac assist system for implanting in the body of a patient, the cardiac assist system comprising:

a main module;

an magnetic-resonance imaging-hardened auxiliary module; and

a communication channel between said main module and said magnetic-resonance imaging-hardened auxiliary module;

said magnetic-resonance imaging-hardened auxiliary module detecting, through said communication channel, failure of said main module;

said magnetic-resonance imaging-hardened auxiliary module including a controller for activating said auxiliary module upon detection of failure of said main module.

2. The cardiac assist system as claimed in claim 1, wherein said main module is a demand pacemaker.

3. The cardiac assist system as claimed in claim 1, wherein said main module is a pacemaker having VVI functionality.

4. The cardiac assist system as claimed in claim 1, wherein said main module is a pacemaker having a defibrillator function.

5. The cardiac assist system as claimed in claim 1, wherein said main module is a pacemaker having a cardioversion function.

6. The cardiac assist system as claimed in claim 1, wherein said magnetic-resonance imaging-hardened auxiliary module is a fixed-rate pacemaker.

7. The cardiac assist system as claimed in claim 1, wherein said main module includes:

a portable power source;

a sensor connector coupled to a lead from a cardiac sensor;

a controller connected to said sensor connector;

a pulsing electrode connector connected to said controller and coupled to a lead of a cardiac pulsing electrode; and

a signaling system for communicating the status of said main module to said magnetic-resonance imaging-hardened auxiliary module.

8. The cardiac assist system as claimed in claim 1, wherein the magnetic-resonance imaging-hardened auxiliary module further includes:

fixed-rate magnetic-resonance imaging-hardened pacing unit circuitry;

an magnetic-resonance imaging-hardened independent power source; and

mode switching circuitry;

said magnetic-resonance imaging-hardened auxiliary module being coupled to a magnetic-resonance imaging-hardened lead.

9. A signaling system for a two-module implantable medical device having a main module and an auxiliary module, comprising:

signaling means in the main module for generating a signal to the auxiliary module, said signal representing a status of the main module or an instruction for the auxiliary module to activate;

sensing means in the auxiliary module, in response to the signal from said signaling means, for determining if the auxiliary module should activate; and

a switch to activate the auxiliary module when the sensing means determines that the signal from said signaling means indicates that the auxiliary module should activate.

10. The signaling system for a two-module implantable medical device as claimed in claim 9, wherein the auxiliary module is adapted to function in standby mode except in the event of failure of the main module.

11. A cardiac assist system, comprising:

a primary device housing;

said primary device housing having a control circuit therein;

a shielding formed around said primary device housing to shield said primary device housing and any circuits therein from electromagnetic interference; and

a lead system to transmit and receive signals between a heart and said primary device housing;

said control circuitry including an oscillator and amplifier operating at an amplitude level above that of an induced signal from a magnetic-resonance imaging field.

12. A cardiac assist system, comprising:

a primary device housing;

said primary device housing having a control circuit therein;

a shielding formed around said primary device housing to shield said primary device housing and any circuits therein from electromagnetic interference;

a lead system to transmit and receive signals between a heart and said primary device housing;

a switch to place the control circuitry into a fixed-rate mode of operation;

a changing magnetic field sensor to sense a change in magnetic field around said primary housing;

said switch placing the control circuitry into a fixed-rate mode of operation when said changing magnetic field sensor senses a predetermined encoded changing magnetic field.

13. A cardiac assist system, comprising:

a primary device housing;

said primary device housing having a control circuit therein;

a shielding formed around said primary device housing to shield said primary device housing and any circuits therein from electromagnetic interference;

a lead system to transmit and receive signals between a heart and said primary device housing;

a switch to place the control circuitry into a fixed-rate mode of operation;

a changing magnetic field sensor to sense a change in magnetic field around said primary housing;

said switch causing the control circuitry to turn-off and cease operation when said changing magnetic field sensor senses a predetermined encoded changing magnetic field.