Telectronics Pacing Systems, Inc.

Telectronics N.v.

Telectronics Pty. Limited

Ibrahim H Ibrahim

Christopher Newton Daly

An implantable device for treating a malfunctioning heart is disclosed. The device includes a high voltage circuit having a tank capacitor for storing therein during a charging mode of operation thereof high voltage DC electrical energy and for delivering such energy to a malfunctioning heart in the form of an electrical shock during a discharging mode of operation thereof. The device further includes a high voltage switch coupled to the high voltage circuit for switching, in the order of microseconds, the high voltage circuit between its charging and discharging modes of operation; a power supply for providing low voltage electrical energy for use in controlling the high voltage switch; a control circuit coupled between the power supply and the high voltage switch and capable of driving the high voltage switch to switch its output in the order of microseconds, for controlling the operation of the high voltage switch; and capacitors for capacitively coupling the power supply to the control circuit and electrically isolating the high voltage DC electrical energy from the power supply. The control circuit includes a common mode switch for rejecting common mode noise, and an additional switch for rapidly changing the output state of the high voltage switch.

Implantable medical devices employing capacitive control of high voltage

A magnetic field sensor including a resonant circuit having a coil. The resonant frequency varies with the strength of the magnetic field which passes through the coil. The resonant circuit is energized for approximately one-half cycle of the resonant frequency which characterizes the circuit in the absence of a magnetic field. During a sensing window of predetermined duration which then immediately follows, the voltage across the coil is examined for a zero crossing. A zero crossing will occur only in the presence of a magnetic field whose amplitude exceeds a threshold value.

Electronic sensor for static magnetic field

A combined telemetry system and magnetic field sensor for use in an implantable medical device. The telemetry system includes a conventional resonant circuit for transmitting and receiving data. The resonant circuit has a coil which is also used to sense the presence of a magnetic field exceeding a threshold value. The resonant frequency varies with the strength of the magnetic field which passes through the coil. Periodically, the resonant circuit is energized, and during a sensing window of predetermined duration which then immediately follows the voltage across the coil is examined for a predetermined number of zero crossings. That number of zero crossings will occur only in the presence of a magnetic field whose amplitude exceeds the threshold value. It is possible to achieve a sensitivity in such a system which is comparable to that of conventional miniature reed switches.

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North Ryde, Australia

Ibrahim H Ibrahim