Abstract:
A timing circuit establishes pulse repetition rate and pulse width and cooperates with a pulse generating output circuit which delivers to an organ a series of stimulating pulses at one of several available pulse energy levels. Low voltage d-c sources are used for driving the timing and output circuits. The output circuit is adapted to selectively double or triple the source voltage and raise the output pulse amplitude to above the response threshold of the organ with an adequate margin of safety. Interaction between the pulse timing and output circuits is minimized. An externally operable magnetic reed switch is used to transfer the stimulus pulse generator from the doubler to the tripler mode.
Abstract:
An implantable body organ stimulator such as an electronic cardiac pacer has a magnetic reed switch and a switch operator embedded in its encapsulation. The state of the reed switch may be changed to alter any one of several functional characteristics of the stimulator with a switch operator which controls the operating state. The operator comprises a magnet which is movable between two positions in a guide tube which is adjacent the reed switch. The magnet may be urged from one position to another with a needle that enters the interior of the guide tube through an aperture in a plate that is embedded in the encapsulation. Means are provided in one embodiment for preventing restoration of the magnet to its original position.