Abstract: An implantable medical device (IMD) may include a plurality of coils that may be used to recharge a power supply of the IMD and/or provide telemetry for the IMD. The IMD may be configured to couple all of the coils in series, such that currents that are induced by each of the coils are added together when the IMD is exposed to an electromagnetic field. The IMD may be configured to alter the coupling of the coils such that the coils are coupled in series opposition, such that currents that are induced by some coils of the IMD are opposed by currents that are induced by other coils of the IMD.

Abstract: An implantable medical device implements a special mode of operation, such as a mode of electrical stimulation therapy, during conditions where there may be an increased likelihood that a device reset will occur. The implantable medical device recovers from the device reset by copying values that specify the special mode and that are stored in a non-volatile memory to an operating memory. The special mode is implemented after the device reset has occurred by using the values copied to the operating memory. One version of the special mode is an MRI mode that allows the implantable medical device to safely operate during an MRI scan. The fields of the MRI scan may trigger a device reset, but the MRI mode values are copied from the non-volatile memory to the operating memory, and the MRI mode is implemented after the reset by using the values copied to the operating memory.

Abstract: An implantable medical device (IMD) may include a plurality of coils that may be used to recharge a power supply of the IMD and/or provide telemetry for the IMD. The IMD may be configured to couple all of the coils in series, such that currents that are induced by each of the coils are added together when the IMD is exposed to an electromagnetic field. The IMD may be configured to alter the coupling of the coils such that the coils are coupled in series opposition, such that currents that are induced by some coils of the IMD are opposed by currents that are induced by other coils of the IMD.

Abstract: An implantable medical device implements a special mode of operation, such as a mode of electrical stimulation therapy, during conditions where there may be an increased likelihood that a device reset will occur. The implantable medical device recovers from the device reset by copying values that specify the special mode and that are stored in a non-volatile memory to an operating memory. The special mode is implemented after the device reset has occurred by using the values copied to the operating memory. One version of the special mode is an MRI mode that allows the implantable medical device to safely operate during an MRI scan. The fields of the MRI scan may trigger a device reset, but the MRI mode values are copied from the non-volatile memory to the operating memory, and the MRI mode is implemented after the reset by using the values copied to the operating memory.

Abstract: An implantable medical device (IMD) may include a plurality of coils that may be used to recharge a power supply of the IMD and/or provide telemetry for the IMD. The IMD may be configured to couple all of the coils in series, such that currents that are induced by each of the coils are added together when the IMD is exposed to an electromagnetic field. The IMD may be configured to alter the coupling of the coils such that the coils are coupled in series opposition, such that currents that are induced by some coils of the IMD are opposed by currents that are induced by other coils of the IMD.

Abstract: An implantable medical device implements a special mode of operation, such as a mode of electrical stimulation therapy, during conditions where there may be an increased likelihood that a device reset will occur. The implantable medical device recovers from the device reset by copying values that specify the special mode and that are stored in a non-volatile memory to an operating memory. The special mode is implemented after the device reset has occurred by using the values copied to the operating memory. One version of the special mode is an MRI mode that allows the implantable medical device to safely operate during an MRI scan. The fields of the MRI scan may trigger a device reset, but the MRI mode values are copied from the non-volatile memory to the operating memory, and the MRI mode is implemented after the reset by using the values copied to the operating memory.

Abstract: A device includes a housing, a first magnetic field sensor, a second magnetic field sensor, and a control module. The housing is configured to be implanted in a patient. The first magnetic field sensor is located at a first location within the housing and is configured to measure a first strength of a magnetic field at the first location. The second magnetic field sensor is located at a second location within the housing and is configured to measure a second strength of the magnetic field at the second location. The control module is configured to identify a source of the magnetic field based on the first and second strengths.

Abstract: An implantable medical device (IMD) may include a plurality of coils that may be used to recharge a power supply of the IMD and/or provide telemetry for the IMD. The IMD may be configured to couple all of the coils in series, such that currents that are induced by each of the coils are added together when the IMD is exposed to an electromagnetic field. The IMD may be configured to alter the coupling of the coils such that the coils are coupled in series opposition, such that currents that are induced by some coils of the IMD are opposed by currents that are induced by other coils of the IMD.

Abstract: A device includes a housing configured to be implanted in a patient. The device also includes a first magnetic field direction sensor located at a first location within the housing and configured to generate a signal representative of a first direction of a magnetic field at the first location, a second magnetic field direction sensor located at a second location within the housing and configured to generate a signal representative of a second direction of the magnetic field at the second location, and a magnetic field strength sensor configured to generate a signal representative of a strength of the magnetic field. The device further includes a control module configured to identify a source of the magnetic field based on at least one of the signal representative of the strength of the magnetic field and the signals representative of the first and second directions of the magnetic field.

Abstract: An implantable medical device implements a special mode of operation, such as a mode of electrical stimulation therapy, during conditions where there may be an increased likelihood that a device reset will occur. The implantable medical device recovers from the device reset by copying values that specify the special mode and that are stored in a non-volatile memory to an operating memory. The special mode is implemented after the device reset has occurred by using the values copied to the operating memory. One version of the special mode is an MRI mode that allows the implantable medical device to safely operate during an MRI scan. The fields of the MRI scan may trigger a device reset, but the MRI mode values are copied from the non-volatile memory to the operating memory, and the MRI mode is implemented after the reset by using the values copied to the operating memory.

Abstract: An implantable medical device implements a special mode of operation, such as a mode of electrical stimulation therapy, during conditions where there may be an increased likelihood that a device reset will occur. The implantable medical device recovers from the device reset by copying values that specify the special mode and that are stored in a non-volatile memory to an operating memory. The special mode is implemented after the device reset has occurred by using the values copied to the operating memory. One version of the special mode is an MRI mode that allows the implantable medical device to safely operate during an MRI scan. The fields of the MRI scan may trigger a device reset, but the MRI mode values are copied from the non-volatile memory to the operating memory, and the MRI mode is implemented after the reset by using the values copied to the operating memory.

Abstract: High voltage charging is aborted when it is detected that a transformer providing the high voltage charge is impaired and is providing an impedance that is too low. In one instance, a voltage for a battery that provides power to the transformer is measured when the battery is substantially unloaded and a voltage is later measured when the battery is loaded during the high voltage charge. A dynamic threshold voltage is computed based on a chosen threshold impedance representing the impedance of the transformer and based the substantially unloaded voltage and on an internal resistance of the battery. When the loaded voltage is less than the threshold voltage, then the high voltage charging is aborted.

Abstract: High voltage charging is aborted when it is detected that a transformer providing the high voltage charge is impaired and is providing an impedance that is too low. In one instance, a voltage for a battery that provides power to the transformer is measured when the battery is substantially unloaded and a voltage is later measured when the battery is loaded during the high voltage charge. A dynamic threshold voltage is computed based on a chosen threshold impedance representing the impedance of the transformer and based the substantially unloaded voltage and on an internal resistance of the battery. When the loaded voltage is less than the threshold voltage, then the high voltage charging is aborted.

Abstract: An implantable medical device implements a special mode of operation, such as a mode of electrical stimulation therapy, during conditions where there may be an increased likelihood that a device reset will occur. The implantable medical device recovers from the device reset by copying values that specify the special mode and that are stored in a non-volatile memory to an operating memory. The special mode is implemented after the device reset has occurred by using the values copied to the operating memory. One version of the special mode is an MRI mode that allows the implantable medical device to safely operate during an MRI scan. The fields of the MRI scan may trigger a device reset, but the MRI mode values are copied from the non-volatile memory to the operating memory, and the MRI mode is implemented after the reset by using the values copied to the operating memory.

Abstract: This disclosure describes techniques for enabling and/or disabling an exposure operating mode using telemetry signals. A telemetry device may be configured to periodically transmit telemetry signals indicating presence of a source of a disruptive energy field in accordance with a communication protocol. An implantable medical device may be configured to receive the telemetry signals from the telemetry device and enter the exposure operating mode in response to receiving a first one of the telemetry signals indicating the presence of the source of the disruptive energy field. The implantable medical device may also exit the exposure operating mode in response to not receiving any of telemetry signals indicating the presence of the source of the disruptive energy field for a predetermined period of time.

Abstract: A device includes a housing configured to be implanted in a patient. The device also includes a first magnetic field direction sensor located at a first location within the housing and configured to generate a signal representative of a first direction of a magnetic field at the first location, a second magnetic field direction sensor located at a second location within the housing and configured to generate a signal representative of a second direction of the magnetic field at the second location, and a magnetic field strength sensor configured to generate a signal representative of a strength of the magnetic field. The device further includes a control module configured to identify a source of the magnetic field based on at least one of the signal representative of the strength of the magnetic field and the signals representative of the first and second directions of the magnetic field.

Abstract: A device includes a housing, a first magnetic field sensor, a second magnetic field sensor, and a control module. The housing is configured to be implanted in a patient. The first magnetic field sensor is located at a first location within the housing and is configured to measure a first strength of a magnetic field at the first location. The second magnetic field sensor is located at a second location within the housing and is configured to measure a second strength of the magnetic field at the second location. The control module is configured to identify a source of the magnetic field based on the first and second strengths.

Abstract: This disclosure describes techniques for enabling and/or disabling an exposure operating mode using telemetry signals. A telemetry device may be configured to periodically transmit telemetry signals indicating presence of a source of a disruptive energy field in accordance with a communication protocol. An implantable medical device may be configured to receive the telemetry signals from the telemetry device and enter the exposure operating mode in response to receiving a first one of the telemetry signals indicating the presence of the source of the disruptive energy field. The implantable medical device may also exit the exposure operating mode in response to not receiving any of telemetry signals indicating the presence of the source of the disruptive energy field for a predetermined period of time.

Abstract: A mechanical response of an implantable medical device (IMD) to a first static magnetic field and a first gradient magnetic field slew rate is simulated by exposing the IMD to a second static magnetic field having a magnitude greater than the first static magnetic field and generating a second gradient magnetic field at the IMD such that a product of the second static magnetic field and a second gradient magnetic field slew rate is substantially equal to a product of the first static magnetic field and the first gradient magnetic field slew rate.

Abstract: A mechanical response of an implantable medical device (IMD) to a first static magnetic field and a first gradient magnetic field slew rate is simulated by exposing the IMD to a second static magnetic field having a magnitude greater than the first static magnetic field and generating a second gradient magnetic field at the IMD such that a product of the second static magnetic field and a second gradient magnetic field slew rate is substantially equal to a product of the first static magnetic field and the first gradient magnetic field slew rate.