Abstract: An implantable medical device is equipped with a magnetic coupling assembly to transfer communication signals to and from the device using electromagnetic energy.

Abstract: A system enables high-frequency communication between an external communication device and one or more implantable medical devices. The system implements a communication protocol in which the external communication device interrogates any implantable medical devices within range to establish one-to-one communication links for purposes of exchanging data and/or programming the medical devices.

Abstract: An implantable cardiac stimulation device is equipped with an isolation system capable of attenuating or eliminating induction currents flowing through the stimulation device by eliminating induction loops. The isolation system comprises a magnetic insulator configured to shield selected components of the stimulation device from external magnetic fields or radio-frequency (RF) signals. The magnetic insulator comprises a plurality of sensors that are configured to detect the intensity of the external magnetic fields and/or RF signals, and a switch bank that electrically isolates certain components of the stimulation device to eliminate the induction loops. The isolation system further comprises an attenuation system comprised of at least one magnetoresistor disposed along potential induction loops to attenuate induction currents when subjected to undesirable external magnetic fields and/or RF signals.

Abstract: A system enables high-frequency communication between an external communication device and one or more implantable medical devices. The system implements a communication protocol in which the external communication device interrogates any implantable medical devices within range to establish one-to-one communication links for purposes of exchanging data and/or programming the medical devices.

Abstract: An implantable medical device is equipped with a magnetic coupling assembly to transfer communication signals to and from the device using electromagnetic energy.

Abstract: A medical system comprising a control device (referred to as a "planet") and a plurality of sensing and stimulating devices (referred to as "satellites") is disclosed. The satellites are relatively small devices that can be thoracoscopically attached to an exterior surface of the heart. The planet can be implanted if desired or, alternatively, externally retained. The planet is capable of wirelessly communicating (i.e., without a direct electrical connection) to each satellite. The planet individually commands each satellite to deliver pacing energy to the heart. Additionally, each satellite is capable of determining when a sense event has occurred at the site of that satellite and transmitting an encoded signal to the planet indicating that a sense event has occurred, along with an identifying code indicating to the planet which satellite detected the sense event.

Abstract: A self-cooling transcutaneous energy transfer system is provided for transmitting power to an implantable medical device, such as a defibrillator. The system includes a housing that is supported above the human body by a base so as to define a space between the housing and the body. A primary induction coil is disposed within the housing for transferring electromagnetic energy to the implantable medical device. A cooling fan is attached to the housing for providing forced convective heat transfer from the body. Various power and control circuitry are provided. The system can transfer away heat generated by eddy currents induced in the implantable device by the magnetic flux produced by the induction coil.

Abstract: An optically-controlled high-voltage switch for an implantable defibrillator. A three-terminal high-voltage-tolerant semiconductor switch exhibits high conductivity between its high-voltage terminal and its common terminal in response to a low control voltage applied between its control terminal and its common terminal, where the low control voltage exceeds a characteristic threshold value, and exhibits low conductivity between same where the control voltage is less than the characteristic threshold value. A photovoltaic coupler/isolator having a light emitting device and a photovoltaic device, optically coupled to and electrically isolated from each other, is in circuit communication across the control and common terminals. A low voltage current source drives the light emitting device of the photovoltaic coupler/isolator.

Abstract: An implantable device, such as a defibrillator which may include cardioversion and pacemaker capabilities, which automatically measures the impedance of the heart prior to the delivery of a cardioverting shock. The defibrillator adjusts the voltage level on output capacitors to deliver a selected energy to the patient's heart. Insulated gate bipolar transistors, or similar devices having an inherent capacitance such that when they are turned on a small voltage gradient will exist across the transistor, are used as switches to control the application of electrical energy to the heart for therapy. When the switches are turned on, a current flows through a connected circuit path, for example through the heart and associated leads. Measurement of the current gives a measure of the impedance of the heart. An initial measurement is performed at the time of implantation of the implantable device, when the initial energy level (and output voltage) is selected.

Abstract: A method of communicating data between an external device and an implantable medical device wherein a first pulse is transmitted as electromagnetic energy from one device to the other, is received and stored as electrostatic energy in the second device and, after a delay period representing data to be communicated, the stored energy is released and transmitted as electromagnetic energy back to the first device. A communications circuit in the implantable device for accomplishing the method includes an antenna coil, a non-linear electronic component in circuit communication with the antenna coil, a storage capacitor in circuit communication with the antenna coil and non-linear electronic component for storing energy received by the antenna coil, and a switch for selectively connecting the charged storage capacitor and the antenna coil to discharge the charge stored in the capacitor into the antenna coil.

Abstract: A method of communicating data between an external device and an implantable medical device wherein a first pulse is transmitted as electromagnetic energy from one device to the other, is received and stored as electrostatic energy in the second device and, after a delay period representing data to be communicated, the stored energy is released and transmitted as electromagnetic energy back to the first device. A communications circuit in the implantable device for accomplishing the method includes an antenna coil, a non-linear electronic component in circuit communication with the antenna coil, a storage capacitor in circuit communication with the antenna coil and non-linear electronic component for storing energy received by the antenna coil, and a switch for selectively connecting the charged storage capacitor and the antenna coil to discharge the charge stored in the capacitor into the antenna coil.

Abstract: An electrical apparatus applies an electric field, e.g. a r.f. field, in a timed manner such that over a given cycle period, e.g. 24 hours, the field is applied for a selected portion of the cycle period and is switched off for the remainder of the period. The periods may be programmable utilizing a microprocessor. The field strength may be selected so as not to produce significant tissue heating, typically less than approximately 100 .mu.w/cm.sup.2, measured at a system surface.