Shunt-current reduction techniques for an implantable therapy system

Patent metadata

Field	Value
Publication number	US-9192769-B2
Application number	US-55133109-A
Country	US
Kind code	B2
Filing date	Aug 31, 2009
Priority date	Oct 31, 2008
Publication date	Nov 24, 2015
Grant date	Nov 24, 2015

Abstract

Techniques for minimizing interference between the first and second medical devices or between the different therapy modules of a common medical device are described herein. In some examples, a medical device may include shunt-current mitigation circuitry and/or at least one clamping structure that helps minimize or even eliminate shunt-current that feeds into a first therapy module of the medical device via one or more electrodes electrically connected to the first therapy module. The shunt-current may be generated by the delivery of electrical stimulation by a second therapy module. The second therapy module may be enclosed in a common housing with the first therapy module or may be separate, e.g., a part of a separate medical device.

First claim

The invention claimed is:

1. A system comprising:
a first therapy module comprising a housing and a signal generator enclosed within the housing, wherein the signal generator is configured to generate and deliver electrical stimulation to a first tissue site within a patient via a first electrode electrically connected to the signal generator;
a second therapy module configured to deliver electrical stimulation to a second tissue site within the patient;
a second, nontherapeutic electrode that is not used by the second therapy module for the delivery of the electrical stimulation by the second therapy module; and
a clamping structure configured to electrically connect the second, nontherapeutic electrode to the housing of the first therapy module, wherein the clamping structure is configured to reduce a shunt-current introduced into the first therapy module via the first electrode, and wherein the shunt-current is generated by the delivery of electrical stimulation by the second therapy module.

2. The system of claim 1 , wherein the clamping structure is configured to electrically connect the second, nontherapeutic electrode to the housing of the first therapy module when a voltage gradient generated by the electrical stimulation delivered by the second therapy module to the second tissue site is greater than or equal to a threshold voltage value, wherein the voltage gradient generates the shunt-current, and wherein the clamping structure is configured to provide a lower impedance electrical path for the shunt-current than an electrical path through the first electrode.

3. The system of claim 1 , wherein the clamping structure comprises one or more of a diode, a Zener diode, a gas plasma arrestor, a varistor, or a combination thereof.

4. The system of claim 1 , wherein the second, nontherapeutic electrode comprises a conductive surface area that is larger than a conductive surface area of the first electrode.

5. The system of claim 1 , wherein the second, nontherapeutic electrode is configured to be implanted in one of a subcutaneous layer, a sub-muscular location, and intravenous location of the patient.

6. The system of claim 1 , wherein the housing substantially encloses the first and second therapy modules.

7. The system of claim 1 , wherein the housing comprises a first outer housing, wherein the system further comprises:
a first implantable medical device (IMD) comprising the first outer housing, the first outer housing enclosing the first therapy module; and
a second IMD comprising a second outer housing enclosing the second therapy module, wherein the first and second outer housings are physically separate from each other and are configured to be separately implanted within the patient.

8. The system of claim 1 , wherein the first therapy module comprises an electrical stimulation module configured to deliver electrical stimulation via the signal generator to the first tissue site, wherein the first tissue site comprises at least one of a nonmyocardial tissue site or a nonvascular cardiac tissue site within the patient, and the second therapy module comprises a cardiac therapy module that is configured to deliver at least one of pacing, cardioversion or defibrillation therapy to the second tissue site, and wherein the second tissue site comprises a heart of the patient.

9. The system of claim 1 , wherein the second therapy module comprises at least one of an automatic external defibrillator, an implantable defibrillator, and intravenous defibrillator.

10. The system of claim 1 , wherein the first therapy module comprises a cardiac therapy module that is configured to deliver at least one of pacing, cardioversion or defibrillation therapy to a heart of the patient, and the second therapy module comprises an electrical stimulation module configured to deliver electrical stimulation to at least one of a nonmyocardial tissue site or a nonvascular cardiac tissue site within the patient.

11. The system of claim 1 , further comprising a shunt-current mitigation circuitry coupled to the first electrode, wherein the shunt-current mitigation circuitry is configured to reduce the shunt-current that is introduced into the first therapy module via the first electrode.

12. The system of claim 11 , wherein the shunt-current mitigation circuitry comprises:
a monitor electrically coupled to the first electrode via a wire, wherein the monitor is configured to monitor an electrical parameter value at the first electrode; and
a switch coupled to the monitor,
wherein the monitor is configured to open the switch when the electrical parameter value is greater than or equal to a threshold value.

13. The system of claim 12 , further comprising a third electrode, wherein the electrical parameter value comprises at least one of a voltage at the first electrode, a current through the first electrode, or a voltage across at least the first and third electrodes.

14. The system of claim 12 , wherein the monitor comprises a voltage monitor.

15. The system of claim 12 , wherein the monitor comprises a current monitor.

16. The system of claim 12 , wherein the wire comprises a resistive wire comprising a resistance of approximately 10 ohms to approximately 10 kiloohms.

17. The system of claim 12 , wherein the switch comprises a relay.

18. The system of claim 11 , wherein the shunt-mitigation circuitry comprises a resistor electrically connected to the first electrode.

19. The system of claim 18 , wherein the shunt-mitigation circuitry further comprises a switch in parallel with the resistor, wherein the first therapy module is configured to toggle the switch closed during the delivery of the delivery of electrical stimulation by the first therapy module.

20. The system of claim 11 , wherein the shunt-mitigation circuitry comprises a diode coupled to the first electrode.

21. The system of claim 11 , wherein the shunt-mitigation circuitry comprises a current limiter coupled to the first electrode.

22. The system of claim 21 , wherein the current limiter comprises at least one of a fuse, a resettable fuse, or a bimetallic circuit breaker.

23. The system of claim 11 , further comprising an implantable medical lead that is electrically connected to the first therapy module and comprising the first electrode, wherein the shunt-current mitigation circuitry is located within at least one of the first therapy module, a connector that electrically connects the implantable medical lead to the first therapy module, or the implantable medical lead.

24. The system of claim 11 , further comprising a processor within the first therapy module, wherein the shunt-current mitigation circuitry comprises:
a monitor electrically coupled to the first electrode via a wire, wherein the monitor is configured to monitor an electrical parameter value at the electrode; and
a switch coupled to the monitor, wherein the processor is configured to open the switch when the electrical parameter value is greater than or equal to a threshold value.

25. The system of claim 1 , further comprising a switch located between the first electrode and the signal generator of the first therapy module, wherein the first therapy module comprises a processor, wherein the second therapy module is configured to transmit a communication signal to the processor that indicates prospective therapy delivery to the patient by the second therapy module, and wherein the processor is configured to ope

Assignees

• Donofrio William T
• Burnes John E
• Krause Paul G
• Arne Gerald P
• Zhou Xiaohong
• Medtronic Inc

Inventors

• Donofrio William T
• Burnes John E
• Krause Paul G
• Arne Gerald P
• Zhou Xiaohong

Classifications

• A61N1/37288

  Communication to several implantable medical devices within one patient · CPC title

• A61N1/3718 Primary

  Monitoring of or protection against external electromagnetic fields or currents · CPC title

• A61N1/36114

  Cardiac control, e.g. by vagal stimulation (stimulating the heart A61N1/362) · CPC title

• A61N1/086

  Magnetic resonance imaging [MRI] compatible leads · CPC title

• A61N1/08

  Arrangements or circuits for monitoring, protecting, controlling or indicating {(for external stimulators A61N1/3603; for implantable neurostimulators A61N1/36128; for heart stimulators A61N1/37; for defibrillators A61N1/3925)} · CPC title