Purdue Research Foundation

Intermedics Inc.

Reese S Terry

Leslie A Geddes

Ross G Baker, Jr

Richard V Calfee

Joe D Bourland

Pat L Gordon

Robert N Bertasz

An external command device and an internal decoding and verification device are used to non-invasively alter the operating parameters of a programmable device implanted in an animal body. Thus, physiological changes can be easily accommodated by the implanted device. In a preferred embodiment, pulse position modulation is used to externally encode the command information. A resulting string of current pulses generates voltage spikes (in the internal decoding device) through inductively coupled coils. Each incoming data bit is verified and the entire command word is verified. After verification, the decoded command is transferred to a command register for simultaneously altering the selected operating parameters. The internal receiver circuitry may conveniently utilize energy from the induced voltage spike, using passive components for forming an output suitable for processing.

Method and apparatus for communicating with implanted body function

Method of and apparatus for automatic defibrillation of the cardiac ventricles of a heart wherein both the mechanical and electrical activities of the ventricles are sensed and used as operating inputs to the controls. Electrical activity is detected and measured with a pair of electrodes, and the waves of an electrocardiogram (ECG) are analyzed. When such electrical analysis indicates that ventricular fibrillation is present and persists, an electrical circuit is actuated for detecting mechanical pumping activity of the heart. Mechanical pumping activity is measured by the change in impedance between the pair of electrodes in one of the ventricles. The change of ventricular impedance is caused by the varying volume of blood contained within the ventricle and depends upon whether the ventricle is in a contracted or a relaxed state. The defibrillator is actuated only when both the mechanical and electrical activity of the ventricle indicates a need for defibrillation. Because some conditions may be encountered which closely resemble ventricular fibrillation, the defibrillator quantitatively preprograms and weighs the relative importance of the electrical and mechanical signals from the heart.

Method of and apparatus for automatically detecting and treating

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Freeport, TX, United States of America

Reese S Terry