MRI SHIELDING IN ELECTRODES USING AC PACING

• US 20090204171A1
• Filed: 02/06/2009
• Published: 08/13/2009
• Est. Priority Date: 02/11/2008
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Ameri, Masoud
• Granted Patent: US 8,255,055 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 2001/0585 Coronary sinus electrodes

Abstract

A medical device includes a pulse generator, an electrode configured to contact tissue in a coronary vessel, a lead comprising a lead conductor, the lead conductor connecting the pulse generator with the electrode, and a filter circuit electrically connected in series between the lead conductor and the electrode. The filter circuit may include a band pass filter that attenuates signals having a frequency other than a natural resonance frequency (e.g. MRI device signals), and the pulse generator may transmit therapy signals to the electrode as a sinusoidal voltage wave at the natural resonance frequency. The filter circuit may include a diode that rectifies the sinusoidal voltage wave before the rectified sinusoidal voltage wave passes to the electrode. In some embodiments, therapy signals may be provided to the electrode through the band pass filter over a natural resonance frequency range.

Claims

1. A medical device, comprising:

a pulse generator;

an electrode configured to contact tissue in a coronary vessel;

a lead comprising a lead conductor, the lead conductor connecting the pulse generator with the electrode; and

a filter circuit electrically connected in series between the lead conductor and the electrode, the filter circuit comprising a band pass filter;

wherein the band pass filter attenuates signals having a frequency other than a natural resonance frequency, and wherein the pulse generator transmits therapy signals to the electrode as a sinusoidal voltage wave at about the natural resonance frequency.

2. The medical device of claim 1, wherein the filter circuit further comprises a rectifier circuit, and wherein the rectifier circuit rectifies the sinusoidal voltage wave before the rectified sinusoidal voltage wave passes to the electrode.

3. The medical device of claim 2, wherein the rectifier circuit comprises a diode.

4. The medical device of claim 2, wherein the rectifier circuit comprises a diode electrically connected in parallel with an inductor and a capacitor.

5. The medical device of claim 2, wherein the sinusoidal voltage wave operates as an alternating current signal, and wherein the rectified sinusoidal voltage wave operates as a direct current signal.

6. The medical device of claim 1, wherein the filter circuit further comprises a resistor electrically connected in parallel with the band pass filter.

7. The medical device of claim 6, wherein a resistance of the resistor shields electromagnetic energy received by the lead conductor from the electrode and creates a link between the lead conductor and the electrode to permit use of the electrode for sensing applications.

8. The medical device of claim 1, wherein the band pass filter comprises a capacitor and an inductor.

9. A medical device, comprising:

an electrode configured to contact tissue in a coronary vessel;

a lead comprising a lead conductor, the lead conductor electrically connecting to the electrode and configured to electrically connect to a pulse generator; and

a filter circuit electrically connected in series between the lead conductor and the electrode, the filter circuit comprising a band pass filter;

wherein the band pass filter attenuates signals having a frequency other than a natural resonance frequency, and wherein the lead conductor receives transmissions of therapy signals from the pulse generator to the electrode as a sinusoidal voltage wave at about the natural resonance frequency.

10. The medical device of claim 9, wherein the filter circuit further comprises a diode, and wherein the diode rectifies the sinusoidal voltage wave before the rectified sinusoidal voltage wave passes to the electrode.

11. The medical device of claim 10, wherein the sinusoidal voltage wave operates as an alternating current signal, and wherein the rectified sinusoidal voltage wave operates as a direct current signal.

12. The medical device of claim 9, wherein the filter circuit further comprises a resistor electrically connected in parallel with the band pass filter.

13. The medical device of claim 12, wherein a resistance of the resistor shields electromagnetic energy received by the lead conductor from the electrode and creates a link between the lead conductor and the electrode to permit use of the electrode for sensing applications.

14. The medical device of claim 9, wherein the band pass filter comprises a capacitor and an inductor.

15. A medical device, comprising:

a pulse generator;

an electrode configured to contact tissue in a coronary vessel;

a lead comprising a lead conductor, the lead conductor electrically connecting the pulse generator with the electrode; and

a filter circuit electrically connected in series between the lead conductor and the electrode, the filter circuit comprising a band pass filter;

wherein the pulse generator is configured to transmit a therapy signal to the electrode through the band pass filter at a frequency within a natural resonance frequency range of the band pass filter, and wherein the band pass filter is configured to shield the electrode from signals with frequencies outside of the natural resonance frequency range.

16. The medical device of claim 15, wherein the pulse generator is configured to transmit the therapy signal to the electrode as a sinusoidal voltage wave.

17. The medical device of claim 16, wherein the filter circuit further comprises a rectifier circuit, and wherein the rectifier circuit rectifies the sinusoidal voltage wave before the rectified sinusoidal voltage wave passes to the electrode.

18. The medical device of claim 17, wherein the rectifier circuit comprises a diode.

19. The medical device of claim 17, wherein the rectifier circuit comprises a diode electrically connected in parallel with an inductor and a capacitor.

20. The medical device of claim 15, wherein the filter circuit further comprises a resistor electrically connected in parallel with the band pass filter.

21. The medical device of claim 20, wherein a resistance of the resistor shields electromagnetic energy received by the lead conductor and creates a link between the lead conductor and the electrode to permit use of the electrode for sensing applications.

22. The medical device of claim 15, wherein the band pass filter comprises a capacitor and an inductor.