MRI detector for implantable medical device
First Claim
Patent Images
1. An implantable medical device, comprising:
- an inductive switching regulator having an inductor with a ferromagnetic core;
a core saturation detector for detecting saturation in the inductor core of the inductive switching regulator indicating the presence of a magnetic field;
wherein the inductive switching regulator alternately stores and discharges energy in an inductor in a two-phase power conversion cycle, the power conversion phases designated as fill and dump phases, respectively, such that the inductor current increases until a predetermined peak current value is reached during the fill phase and decreases to zero or other predetermined value during the dump phase;
circuitry for measuring the duration of at least part of a power conversion cycle;
wherein the core saturation detector detects core saturation if the duration of the measured duration of the power conversion cycle exceeds a specified threshold value; and
,circuitry for altering the behavior of the device when core saturation is detected.
1 Assignment
0 Petitions
Accused Products
Abstract
An implantable medical device with an inductive switching regulator having an inductor with a ferromagnetic core is described. The device incorporates a core saturation detector for detecting saturation in the inductor core indicating the presence of a magnetic field such as produced by an MRI scan. The device is configured to alter its behavior when core saturation is detected such as by entering an MRI mode that may include cessation of therapy, fixed-rate bradycardia pacing, and/or disablement of tachyarrhythmia therapy.
60 Citations
20 Claims
-
1. An implantable medical device, comprising:
-
an inductive switching regulator having an inductor with a ferromagnetic core; a core saturation detector for detecting saturation in the inductor core of the inductive switching regulator indicating the presence of a magnetic field; wherein the inductive switching regulator alternately stores and discharges energy in an inductor in a two-phase power conversion cycle, the power conversion phases designated as fill and dump phases, respectively, such that the inductor current increases until a predetermined peak current value is reached during the fill phase and decreases to zero or other predetermined value during the dump phase; circuitry for measuring the duration of at least part of a power conversion cycle; wherein the core saturation detector detects core saturation if the duration of the measured duration of the power conversion cycle exceeds a specified threshold value; and
,circuitry for altering the behavior of the device when core saturation is detected. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 10)
-
-
9. An implantable medical device, comprising:
-
an inductive switching regulator having an inductor with a ferromagnetic core, wherein the inductive switching regulator is configured to operate in a clocked frequency or pulse width modulation control mode; a core saturation detector for detecting saturation in the inductor core of the inductive switching regulator indicating the presence of a magnetic field; circuitry for altering the behavior of the device when core saturation is detected; circuitry for measuring the peak inductor current during a power conversion cycle; and
,wherein the core saturation detector detects core saturation if the peak inductor current exceeds a specified threshold value.
-
-
11. A method for operating an implantable medical device incorporating an inductive switching regulator having an inductor with a ferromagnetic core, comprising:
-
operating the inductive switching regulator to alternately store and discharge energy in the inductor in a two-phase power conversion cycle, the power conversion phases designated as fill and dump phases, respectively, such that the inductor current increases until a predetermined peak current value is reached during the fill phase and decreases to zero or other predetermined value during the dump phase, detecting saturation in the inductor core of the inductive switching regulator indicating the presence of a magnetic field by measuring the duration of at least part of a power conversion cycle and detecting core saturation if the duration of the measured duration of the power conversion cycle exceeds a specified threshold value; and
,altering the behavior of the device when core saturation is detected. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 20)
-
-
19. A method for operating an implantable medical device incorporating an inductive switching regulator having an inductor with a ferromagnetic core, comprising:
-
operating the inductive switching regulator in a clocked frequency modulation or pulse width modulation control mode; detecting saturation in the inductor core of the inductive switching regulator indicating the presence of a magnetic field by measuring the peak inductor current during a power conversion cycle and detecting core saturation if the peak inductor current exceeds a specified threshold value; and altering the behavior of the device when core saturation is detected.
-
Specification