Implantable cardioverter defibrillator designed for use in a magnetic resonance imaging environment

• US 9,101,782 B2
• Filed: 08/04/2013
• Issued: 08/11/2015
• Est. Priority Date: 08/19/2011
• Status: Active Grant

• Current Assignee: Greatbatch Limited (Greatbatch Incorporated)
• Original Assignee: Greatbatch Limited (Greatbatch Incorporated)
• Inventors: Frustaci, Dominick J., Muffoletto, Barry C., Stevenson, Robert A.
• Primary Examiner(s): VOORHEES, CATHERINE M
• Application Number:
  US13/958,582
• Publication Number:
  US 20130317345A1
• Time in Patent Office: 737 Days
• Field of Search: 607 31- 32, 607/9, 607/34, 607 62- 63, 607115-116, 607/119, 600410-411
• US Class Current: 1/1
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61N 1/3718 Monitoring of or protection against external electromagnetic fields or currents
• CPC Class Codes: A61N 1/3925 Monitoring; Protecting
• CPC Class Codes: A61N 1/3987 characterised by the timing or triggering of the shock

Abstract

An implantable cardioverter defibrillator includes a communication interface operable to receive a communication signal from an external programmer. The communication signal includes a command to switch the ICD from a first mode to a second mode. A processor is in electrical communication with the communication interface and configured to switch the ICD between the first and second modes. A battery is configured to supply low DC voltage. A converter is configured to convert the low DC voltage to a high DC voltage. An energy storage capacitor is electrically coupled to the converter and configured to store a therapeutic energy or high DC voltage including at least 15 joules. The second mode includes activating the converter to convert the low DC voltage to the high DC voltage and storing the therapeutic energy or at least 15 joules within the energy storage capacitor during a period of time of the second mode.

Claims

1. A method of performing a magnetic resonance imaging (MRI) scan on a patient having an implanted cardioverter defibrillator (ICD), comprising the steps of:

determining that the ICD comprises a ferrite core high voltage power supply transformer;

with the ICD not being in the presence of an MRI field generated by an MRI scanner, sending a communication signal from an external programmer to the ICD, the communication signal being a command to precharge an energy storage capacitor of the ICD before the patient undergoes an MRI scan, the command also switching the ICD into an MRI mode, where the MRI mode is configured to autonomously detect a dangerous ventricular arrhythmia and when needed deliver a precharged defibrillation shock;

moving the patient into the MRI scanner;

performing the MRI scan;

removing the patient from the MRI scanner after the MRI scan is completed or after the ICD delivers a first defibrillation shock to the patient while in the presence of the MRI field;

moving the patient substantially away from the MRI field; and

determining that the ICD has not delivered the first defibrillation shock and allowing the ICD to automatically bleed off a first electrical charge stored in the energy storage capacitor, or

if the ICD has delivered the first defibrillation shock and it is determined that additional therapy is needed, allowing the ICD to recharge the energy storage capacitor and deliver a second defibrillation shock to the patient.

2. The method of claim 1, including the step of monitoring the status of the patient or ICD while performing the MRI scan.

3. The method of claim 2, wherein monitoring the status of the patient comprises monitoring EKG or pulse ox of the patient.

4. The method of claim 3, including the step of sounding an alarm for emergency personnel when the ICD delivers the first defibrillation shock.

5. The method of claim 1, wherein the step of performing the MRI scan comprises more than 20 minutes.

6. The method of claim 1, wherein the first or second defibrillation shocks each comprise at least 15 joules.

7. The method of claim 1, wherein the first or second defibrillation shocks each comprise at least 30 joules.

8. The method of claim 1, including the step of sending a second communication signal from the external programmer to the ICD, wherein the second communication signal comprises a second command to switch the ICD to a non-MRI mode.

9. The method of claim 1, wherein the ICD comprises a magnetic field sensor in electrical communication with a processor for the ICD and wherein the processor is configured to switch the ICD to a non-MRI mode when the magnetic field sensor detects a lack of a static magnetic field, and including the step of allowing the ICD to switch to the non-MRI mode.

10. A method of performing a magnetic resonance imaging (MRI) scan on a patient having an implanted cardioverter defibrillator (ICD), comprising the steps of:

providing the ICD comprising;

a hermetically sealed housing;

a communication interface disposed within the housing operable to receive a communication signal from an external programmer, wherein the communication signal comprises a command to switch the ICD in the absence of a dangerous ventricular arrhythmia from a normal operating mode to an MRI mode;

a processor disposed within the housing in electrical communication with the communication interface, the processor configured to switch the ICD between the normal operating and MRI modes;

a battery disposed within the housing configured to supply a low DC voltage;

a converter comprising a ferrite core transformer disposed within the housing configured to convert the low DC voltage to a high DC voltage; and

an energy storage capacitor disposed within the housing electrically coupled to the converter, wherein the energy storage capacitor is configured to store the high DC voltage;

wherein the MRI mode comprises precharging the energy storage capacitor by activating the converter to convert the low DC voltage to the high DC voltage and storing the high DC voltage within the energy storage capacitor during a period of time of the MRI mode, wherein the MRI mode is configured to autonomously detect the dangerous ventricular arrhythmia, where the implantable cardioverter defibrillator is precharged outside the presence of an MRI main static field and then can deliver a first defibrillation shock while in the presence of the MRI main static field;

with the ICD not being in the presence of the MRI main static field generated by an MRI scanner, sending the communication signal from the external programmer to the ICD, the communication signal being the command to switch the ICD from the normal operating mode to the MRI mode thereby charging the energy storage capacitor of the ICD before the patient undergoes an MRI scan;

moving the patient into the MRI scanner;

performing the MRI scan;

removing the patient from the MRI scanner after the MRI scan is completed or after the ICD delivers the first defibrillation shock while in the presence of the MRI main static field;

moving the patient substantially away from the MRI main static field; and

determining that the ICD has not delivered the first defibrillation shock and allowing the ICD to automatically bleed off a first electrical charge stored in the energy storage capacitor, or if the ICD has delivered the first defibrillation shock and it is determined that additional therapy is needed, allowing the ICD to recharge the energy storage capacitor and deliver a second defibrillation shock to the patient.

11. The method of claim 10, including the step of monitoring the status of the patient or ICD while performing the MRI scan.

12. The method of claim 11, wherein monitoring the status of the patient comprises monitoring EKG or pulse ox of the patient.

13. The method of claim 12, including the step of sounding an alarm for emergency personnel when the ICD delivers the first defibrillation shock.

14. The method of claim 10, wherein the step of performing the MRI scan comprises more than 20 minutes.

15. The method of claim 10, wherein the first or second defibrillation shock comprises at least 15 joules.

16. The method of claim 10, wherein the first or second defibrillation shock comprises at least 30 joules.

17. The method of claim 10, including the step of sending a second communication signal from the external programmer to the ICD, wherein the second communication signal comprises a second command to switch the ICD from the MRI mode to the normal operating mode.

18. The method of claim 10, wherein the ICD comprises a magnetic field sensor in electrical communication with the processor and wherein the processor is configured to switch the ICD from the MRI mode to the normal operating mode when the magnetic field sensor detects a lack of a static magnetic field, and including the step of allowing the ICD to switch from the MRI mode to the normal operating mode.

19. A method of performing a magnetic resonance imaging (MRI) scan on a patient having an implanted cardioverter defibrillator (ICD), comprising the steps of:

determining that the ICD comprises a ferrite core transformer that is a component of a high energy storage capacitor charging circuit;

with the ICD not being in the presence of an MRI main static field generated by an MRI scanner, sending a communication signal from an external programmer to the ICD, the communication signal being a command to charge the high energy storage capacitor of the ICD before the patient undergoes an MRI scan, the command also switching the ICD into an MRI mode, where the MRI mode is configured to autonomously detect a dangerous ventricular arrhythmia and when needed deliver a precharged defibrillation shock;

moving the patient in close proximity to the MRI scanner;

performing the MRI scan comprising more than 20 minutes;

removing the patient from close proximity to the MRI scanner when the MRI scan is completed or when the ICD delivers a first defibrillation shock of at least 15 joules while in the presence of the MRI field;

moving the patient substantially away from the MRI field; and

determining that the ICD has not delivered the first defibrillation shock and allowing the ICD to automatically bleed off a first electrical charge stored in the high energy storage capacitor, or if the ICD has delivered the first defibrillation shock and it is determined that additional therapy is needed, allowing the ICD to recharge the high energy storage capacitor and deliver a second defibrillation shock to the patient.

20. The method of claim 19, including the step of sending a second communication signal from the external programmer to the ICD, wherein the second communication signal comprises a second command to switch the ICD to a non-MRI mode.

21. The method of claim 19, wherein the ICD comprises a magnetic field sensor in electrical communication with the processor and wherein the processor is configured to switch the ICD to a non-MRI mode when the magnetic field sensor detects a lack of a static magnetic field, and including the step of allowing the ICD to switch to the non-MRI mode.