THERAPY CIRCUIT PROTECTION FOR IMPLANTABLE MEDICAL DEVICE

• US 20120004694A1
• Filed: 06/22/2011
• Published: 01/05/2012
• Est. Priority Date: 07/01/2010
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Ludwig, Jacob M., Linder, William J., Stessman, Nicholas J., Stubbs, Scott R., Stahmann, Jeffrey E., Foster, Arthur, Brandner, Douglas J., Hannan, Douglas Michael
• Granted Patent: US 8,649,862 B2
• Time in Patent Office: Days
• US Class Current: 607/7
• CPC Class Codes: A61N 1/025 Digital circuitry features of electrotherapy devices, e.g. memory, clocks, processors
• CPC Class Codes: A61N 1/3706 Pacemaker parameters stimulation threshold A61N1/371
• CPC Class Codes: A61N 1/3931 Protecting, e.g. back-up systems
• CPC Class Codes: A61N 1/3937 Monitoring output parameters
• CPC Class Codes: A61N 1/39622 Pacing therapy

Abstract

A medical device can include a therapy circuit configured to provide a specified electrostimulation therapy to a tissue site, the specified electrostimulation therapy including a scheduled completion, the therapy circuit including a protection circuit configured to adjust specification of the electrostimulation therapy being provided so as to provide an adjusted electrostimulation therapy before the scheduled completion. The medical device can include a monitoring circuit comprising a comparator. The monitoring circuit can be configured to trigger the protection circuit to inhibit the therapy circuit when the therapy circuit output parameter exceeds the specified threshold as indicated by the comparator.

Claims

1. A system, comprising:

a medical device, comprising;

a therapy circuit configured to provide a specified electrostimulation therapy to a tissue site, the specified electrostimulation therapy including a scheduled completion, the therapy circuit including a protection circuit configured to adjust specification of the electrostimulation therapy being provided so as to provide an adjusted electrostimulation therapy before the scheduled completion;

a monitoring circuit comprising a comparator, the monitoring circuit configured to monitor a therapy circuit output parameter using the comparator during providing the specified electro stimulation therapy;

wherein the comparator is configured to compare the therapy circuit output parameter with a specified threshold; and

wherein the monitoring circuit is configured to trigger the protection circuit to adjust specification of the electrostimulation when the therapy circuit output parameter exceeds the specified threshold as indicated by the comparator.

2. The system of claim 1, wherein the protection circuit is configured to inhibit the therapy circuit from completing the specified electrostimulation therapy.

3. The system of claim 1, wherein the monitoring circuit includes a latency of about 1 microsecond or less, the latency comprising an interval beginning when the therapy circuit output parameter exceeds the specified threshold and ending with an assertion of a trigger to the protection circuit by the monitoring circuit to inhibit the therapy circuit.

4. The system of claim 1, wherein the medical device includes a processor circuit;

and

wherein the monitoring circuit and the protection circuit are configured to operate asynchronously with respect to the processor circuit.

5. The system of claim 1, wherein the medical device includes a processor circuit;

and

wherein the monitoring circuit is coupled to the processor circuit and configured to provide information to the processor circuit indicative of a fault when the therapy circuit output parameter exceeds the specified threshold as indicated by the comparator.

6. The system of claim 5, wherein the processor is configured to enable the therapy circuit to at least attempt to complete the specified electrostimulation therapy, despite the information indicative of the fault, when an override is asserted.

7. The system of claim 6, wherein the processor includes a counter configured to count a number of faults;

and

wherein the processor is configured to enable the therapy circuit to at least attempt to complete the specified electrostimulation therapy when the count of the number of faults exceeds a specified count.

8. The system of claim 6, wherein the processor includes a timer configured to measure an arrhythmia episode duration;

and

wherein the processor is configured to enable the therapy circuit to at least attempt to complete the electrostimulation therapy when the arrhythmia episode duration exceeds a specified duration, despite the information indicative of a fault.

9. The system of claim 5, wherein the therapy circuit is configured to provide an electrostimulation therapy using an adjusted electrostimulation therapy output parameter provided by the processor using the information indicative of a fault, the adjusted electrostimulation therapy output parameter including one or more of an adjusted current, an adjusted voltage, an adjusted power, or an adjusted energy, as compared to a specified therapy output parameter that would be provided in the absence of the fault.

10. The system of claim 5, wherein the therapy circuit is configured to controllably provide the electrostimulation therapy to one or more of a first electrode combination at or near the tissue site, or to a second electrode combination, using an electrode selection provided the processor circuit, and using the information indicative of a fault.

11. The system of claim 1, wherein the therapy circuit includes a conductor, wherein the therapy circuit output parameter includes an output current through the conductor, and wherein the comparator is configured to compare a voltage developed across a specified portion of the conductor with the specified threshold.

12. The system of claim 1, wherein the medical device includes an implantable medical device;

and

wherein the system further comprises an implantable lead electrically and mechanically coupled to the implantable medical device, the implantable lead including an electrode implantable at or near the tissue site.

13. The system of claim 1, wherein the therapy circuit includes an insulated gate bipolar transistor (IGBT);

wherein the therapy circuit is configured to provide the electrostimulation therapy at least in part using the IGBT; and

wherein the protection circuit is configured to control a gate of the IGBT to inhibit conduction of the electrostimulation therapy in response to a trigger provided by the monitoring circuit.

14. The system of claim 1, wherein the therapy circuit includes an insulated gate bipolar transistor (IGBT) coupled to a gate-turn-off (GTO) thyristor;

wherein the therapy circuit is configured to provide the electrostimulation therapy at least in part using the GTO thyristor, and at least in part using the IGBT to control the conduction state of the GTO thyristor; and

wherein the protection circuit is configured to control a gate of the IGBT to inhibit conduction of the electrostimulation therapy by the GTO thyristor in response to a trigger provided by the monitoring circuit.

15. An implantable medical device including a processor circuit and a memory circuit, the memory circuit including instructions that, when performed by the processor circuit, cause the implantable medical device to:

provide a specified electrostimulation therapy to a tissue site using a therapy circuit, the specified electrostimulation therapy including a scheduled completion;

monitor a therapy circuit output parameter using a monitoring circuit during the providing the specified electrostimulation therapy, including comparing a therapy circuit output parameter to a specified threshold; and

adjust the specification of the electrostimulation therapy being provided using a protection circuit when the therapy circuit output parameter exceeds the specified threshold so as to provide an adjusted electrostimulation therapy before the scheduled completion.

16. The implantable medical device of claim 15, wherein the monitoring circuit and the protection circuit are configured to operate asynchronously with respect to a processor circuit.

17. The implantable medical device of claim 15, wherein the memory circuit includes instructions that cause the implantable medical device to:

provide information indicative of a fault to the processor circuit in response to the therapy output parameter exceeding the specified threshold; and

enable the therapy circuit to at least attempt to complete the specified electrostimulation therapy despite the information indicative of the fault.

18. The implantable medical device claim 17, wherein the memory circuit includes instructions that cause the implantable medical device to:

count a number of faults; and

enable the therapy circuit to at least attempt to complete the specified electrostimulation therapy despite the information indicative of a fault when a count of the number of faults exceeds a specified count.

19. The implantable medical device claim 17, wherein the memory circuit includes instructions that cause the implantable medical device to:

measure an arrhythmia episode duration; and

enable the therapy circuit to at least attempt to complete the specified electrostimulation therapy despite the information indicative of a fault when the arrhythmia episode duration exceeds a specified duration.

20. The implantable medical device claim 17, wherein the memory circuit includes instructions that cause the implantable medical device to:

provide an electrostimulation therapy using an adjusted electrostimulation therapy output parameter provided by the processor in response to the information indicative of a fault, the adjusted electrostimulation therapy output parameter including one or more of an adjusted current, an adjusted voltage, an adjusted power, or an adjusted energy, as compared to a specified therapy output parameter that would be provided in the absence of the fault.