Control of externally induced current in implantable medical devices

• Main Authors: STEIN MARC T, HARTLAUB JEROME T
• Format: Patent
• Language: English
• Published: 03.04.2001
• Edition: 7
• Subjects: ELECTROTHERAPY; HUMAN NECESSITIES; HYGIENE; MAGNETOTHERAPY; MEDICAL OR VETERINARY SCIENCE; RADIATION THERAPY; ULTRASOUND THERAPY

A current limiting apparatus that is adapted to be operatively connected as part of a conductive loop formed by a medical device implanted within a living organism having electrically excitable tissue. This apparatus limits unwanted current in the conductive loop that may be induced by a significant level of an external signal such as a time-alternating electromagnetic field. This apparatus includes a switch for introducing a high impedance into the conductive loop when the switch is turned off. The apparatus also includes a control circuit that controls the switch to be turned on when the conductive loop should be closed to stimulate the electrically excitable tissue for a therapeutic effect. The control circuit turns the switch off whenever the living organism enters an area having a significant level of external signal that may induce unwanted current in the conductive loop to limit the unwanted current. The living organism can manually initiate turning off the switch when the living organism is about to enter an area having such an external signal. Alternatively, such an external signal is sensed to turn the switch off automatically when such an external signal is sensed.