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

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.

1 . An implantable cardioverter defibrillator, 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 implantable cardioverter defibrillator from a first mode to a second mode;   a processor disposed within the housing in electrical communication with the communication interface, the processor configured to switch the implantable cardioverter defibrillator between the first and second modes;   a battery disposed within the housing configured to supply a low DC voltage;   a DC to AC converter disposed within the housing electrically coupled to the battery and configured to convert the low DC voltage to a low AC voltage;   a transformer disposed within the housing electrically coupled to the DC to AC converter configured to convert the low AC voltage to a high AC voltage;   a rectifier disposed within the housing electrically coupled to the transformer and configured to convert the high AC voltage to a high DC voltage;   an energy storage capacitor disposed within the housing electrically coupled to the rectifier, wherein the energy storage capacitor is configured to store the high DC voltage comprising at least 15 joules;   a high voltage switch disposed within the housing electrically coupled to the energy storage capacitor;   a bleed off circuit disposed within the housing electrically coupled to the high energy storage capacitor; and   a timer in electrical communication with the processor operable to measure a period of time of the second mode, wherein the processor is configured to switch the implantable cardioverter defibrillator from the second mode to the first mode after the period of time has elapsed and activate the bleed off circuit to dissipate the at least 15 joules;   wherein the second mode comprises activating the DC to AC converter, transformer and rectifier to change the low DC voltage to the high DC voltage and storing the at least  15  joules within the energy storage capacitor during the period of time of the second mode;   such that the implantable cardioverter defibrillator can deliver a therapeutic cardioversion or defibrillation shock while in the presence of an MRI field.   
     
     
         2 . The implantable cardioverter defibrillator of  claim 1 , wherein the period of time of the second mode comprises more than 20 minutes. 
     
     
         3 . The implantable cardioverter defibrillator of  claim 1 , wherein the at least 15 joules comprises at least 30 joules. 
     
     
         4 . An implantable medical device, 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 implantable medical device from a first mode to a second mode;   a processor disposed within the housing in electrical communication with the communication interface, the processor configured to switch the implantable medical device between the first and second modes;   a battery disposed within the housing configured to supply a low DC voltage;   a converter 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 second mode comprises 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 second mode;   such that the implantable cardioverter defibrillator can deliver a therapeutic cardioversion or defibrillation shock while in the presence of an MRI field.   
     
     
         5 . The implantable medical device of  claim 4 , wherein the converter comprises a DC to AC converter or switch mode power supply disposed within the housing electrically coupled to the battery and configured to convert the low DC voltage to a low AC voltage. 
     
     
         6 . The implantable medical device of  claim 5 , wherein the converter comprises a transformer disposed within the housing electrically coupled to the DC to AC converter or switch mode power supply configured to convert the low AC voltage to a high AC voltage. 
     
     
         7 . The implantable medical device of  claim 6 , wherein the converter comprises a rectifier disposed within the housing electrically coupled to the transformer and configured to convert the high AC voltage to the high DC voltage. 
     
     
         8 . The implantable medical device of  claim 4 , including a high voltage switch disposed within the housing electrically coupled to the energy storage capacitor. 
     
     
         9 . The implantable medical device of  claim 4 , including a bleed off circuit disposed within the housing electrically coupled to the energy storage capacitor. 
     
     
         10 . The implantable medical device of  claim 9 , wherein the processor activates the bleed off circuit to dissipate the high DC voltage when switching the second mode to the first mode. 
     
     
         11 . The implantable medical device of  claim 4 , wherein the period of time of the second mode comprises more than 20 minutes. 
     
     
         12 . The implantable medical device of  claim 4 , wherein the high DC voltage comprises at least 15 joules. 
     
     
         13 . The implantable medical device of  claim 4 , wherein the high DC voltage comprises at least 30 joules. 
     
     
         14 . The implantable medical device of  claim 4 , including a timer in electrical communication with the processor operable to measure the period of time of the second mode, wherein the processor is configured to switch the implantable medical device from the second mode to the first mode after the period of time has elapsed. 
     
     
         15 . The implantable medical device of  claim 4 , wherein the communication interface is operable to receive a second communication signal from the external programmer, wherein the second communication signal comprises a second command to switch the implantable medical device from the second mode to the first mode. 
     
     
         16 . The implantable medical device of  claim 4 , including a magnetic field sensor in electrical communication with the processor, wherein the processor is configured to switch the implantable medical device from the second mode to the first mode when the magnetic field sensor detects a lack of a static magnetic field. 
     
     
         17 . An implantable medical device, comprising:
 a communication interface operable to receive a communication signal from an external programmer, wherein the communication signal comprises a command to switch the implantable medical device from a first mode to a second mode;   a processor in electrical communication with the communication interface, the processor configured to switch the implantable medical device between the first and second modes;   a battery configured to supply a low DC voltage;   a converter configured to convert the low DC voltage to a high DC voltage; and   an energy storage capacitor electrically coupled to the converter, wherein the energy storage capacitor is configured to store the high DC voltage;   wherein the second mode comprises 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 second mode.   
     
     
         18 . The implantable medical device of  claim 17 , wherein the converter comprises a DC to AC converter electrically coupled to the battery and configured to convert the low DC voltage to a low AC voltage. 
     
     
         19 . The implantable medical device of  claim 18 , wherein the converter comprises a transformer electrically coupled to the DC to AC converter configured to convert the low AC voltage to a high AC voltage. 
     
     
         20 . The implantable medical device of  claim 19 , wherein the converter comprises a rectifier electrically coupled to the transformer and configured to convert the high AC voltage to the high DC voltage. 
     
     
         21 . The implantable medical device of  claim 17 , including a high voltage switch electrically coupled to the energy storage capacitor. 
     
     
         22 . The implantable medical device of  claim 17 , including a bleed off circuit electrically coupled to the energy storage capacitor, wherein the processor activates the bleed off circuit to dissipate the high DC voltage when switching the second mode to the first mode. 
     
     
         23 . The implantable medical device of  claim 17 , wherein the period of time of the second mode comprises more than 20 minutes. 
     
     
         24 . The implantable medical device of  claim 17 , wherein the high DC voltage comprises at least 15 joules. 
     
     
         25 . The implantable medical device of  claim 17 , wherein the high DC voltage comprises at least 30 joules. 
     
     
         26 . The implantable medical device of  claim 17 , including a timer in electrical communication with the processor operable to measure the period of time of the second mode, wherein the processor is configured to switch the implantable medical device from the second mode to the first mode after the period of time has elapsed. 
     
     
         27 . The implantable medical device of  claim 17 , wherein the communication interface is operable to receive a second communication signal from the external programmer, wherein the second communication signal comprises a second command to switch the implantable medical device from the second mode to the first mode. 
     
     
         28 . The implantable medical device of  claim 17 , including a magnetic field sensor in electrical communication with the processor, wherein the processor is configured to switch the implantable medical device from the second mode to the first mode when the magnetic field sensor detects a lack of a static magnetic field. 
     
     
         29 . The implantable medical device of  claim 17 , wherein the external programmer comprises a self-contained hand-held device operable to switch the implantable medical device between the first and second modes. 
     
     
         30 . The implantable medical device of  claim 29 , wherein the hand-held device comprises a display indicating the mode of the implantable medical device. 
     
     
         31 . The implantable medical device of  claim 29 , wherein the hand-held device comprises a first button operable to switch the implantable medical device from the first mode to the second mode. 
     
     
         32 . The implantable medical device of  claim 31 , wherein the hand-held device comprises a second button operable to switch the implantable medical device from the second mode to the first mode. 
     
     
         33 . A method of performing a magnetic resonance imaging (MRI) scan on a patient with an implanted cardioverter defibrillator (ICD), comprising:
 sending a communication signal from an external programmer to the ICD absent a presence of an MRI field generated by an MRI scanner, the communication signal comprising a command to charge an energy storage capacitor of the ICD before the patient undergoes the MRI scan;   moving the patient in close proximity to the MRI scanner;   performing the MRI scan;   removing the patient from the MRI scanner when the MRI scan is completed or when the ICD delivers a therapeutic charge or defibrillation shock while in the presence of the MRI field;   moving the patient substantially away from the MRI field; and   allowing the ICD to automatically bleed off an electrical charge stored in the energy storage capacitor after completing the MRI scan, or, allowing the ICD to recharge the energy storage capacitor and deliver a second therapeutic charge or defibrillation shock to the patient.   
     
     
         34 . The method of  claim 33 , including the step of monitoring the status of the patient or ICD while performing the MRI scan. 
     
     
         35 . The method of  claim 34 , wherein monitoring the status of the patient comprises monitoring EKG or pulse ox of the patient. 
     
     
         36 . The method of  claim 33 , including the step of sounding an alarm for emergency personnel when the ICD delivers the therapeutic charge or defibrillation shock.