Implantable digital cardiac pacer having externally selectible operating parameters and "one shot" digital pulse generator for use therein

An implantable digital cardiac pacer adapted to deliver stimulation pulses to a heart contacting electrode having externally selectible operating parameters comprising:

• a heart stimulation pulse generator for connection to said electrode;
• an external instruction device adapted to transmit a train of parameter selection pulses;
• means for receiving said train of pulses and for generating a digital signal in response thereto;
• memory means for storing said digital signal;
• means interconnecting said pulse receiving means and said memory means to permit the loading of said digital signal into said memory means only after said train of pulses is entirely received by said receiving means;
• means for varying at least one of the operating parameters of said pulse generator;
• and means connecting said memory means and said parameter varying means to enable said parameter varying means to control said at least one operating parameter in response to said digital signal.

A heart pacer having a pulse generator for delivering stimulation pulses to a heart contacting electrode and having selectible discrete operating parameters, comprising:

• means for receiving a train of pulses of number corresponding to a preassigned pacer parameter combination;
• means for counting the pulses received to produce a binary signal representing the number of said pulses in said train;
• memory means into which said binary signal is loaded;
• counting means connected to said memory means to permit said binary signal to be loaded into said memory only after the train of pulses is entirely received;
• and control means connected to said memory means to select said operating parameters in said preassigned parameter combination for controlling said pulse generator.

For use in a digital heart pacer of the type which receives externally transmitted pulses, a "one shot" digital pulse generator for producing a pulse of controlled amplitude and width upon the application of said received pulse, comprising:

• a source of digital "high" and "low" states;
• a clock pulse generator;
• first and second flip-flop means each having a data input terminal, an output terminal, an inverted output terminal, a clock terminal operable to produce a next state output in accordance with the present state input, and a reset terminal;
• said received pulse being conducted to the clock input of said first flip-flop, said data input terminal of said first flip-flop being connected to a digital "high" state, and the output of said first flip-flop being connected to the data input of said second flip-flop, and additionally defining the output of said digital "one shot" generator;
• counter means having a clock input and an output which changes state after the application of a predetermined number of clock pulses to the clock input, and a reset terminal to initialize said counter;
• said counter being reset by the signal on the inverted output terminal of said first flip-flop, and providing a signal upon said output terminal to said clock terminal of said second flip-flop, said counter receiving clock pulses from a clock generator upon its clock input terminal;
• the output from said second flip-flop being connected to reset said first and second flip-flops to an initial state;
• whereby upon the application of a received pulse to said first flip-flop, an output is presented upon its output terminals which is of predetermined amplitude, continuing until said first and second flip-flops are reset as controlled by the count output of said counter.

A circuit for controlling the parameters of an implantable cardiac pacer responsive to remote signals having a first portion defining an access code having both high and low logic states, and a second portion defining a parameter controlling code comprising,

• means for receiving said remote signals,
• access code recognizing circuit means for signalling the reception of said access code having both high and low logic states,
• means for counting said second portion of said remote signals to produce a digital representation thereof,
• gate means receiving said second portion for passing said second portion only after said access code recognizing circuit signals reception of said access code,
• storage means for loading thereinto said digital representation of said second portion from said counting means for controlling the pacer parameters,
• means for controlling the pacer parameters in accordance with said parameter controlling code in response to said digital representation loaded into said storage means.

A circuit for controlling after the reception of a cardiac signal or a stimulation signal the refractory period of an implantable digital cardiac pacer having a resettable stimulation pulse interval controlling means comprising:

• means for producing a first reset signal upon detecting a cardiac or a stimulation signal,
• a source of clock pulses,
• a counter resettable by said first reset signal for counting said clock pulses after the occurrence of said first reset signal to produce at least first and second output signals at predetermined clock pulse counts,
• signal selection means responsive to a digital signal applied to an input thereof and having inputs to which said first and second output signals are applied to produce a selected signal determined by said digital signal,
• means for generating said digital signal in response to a remotely generated control signal, and
• means to produce a second reset signal for resetting said stimulation pulse interval controlling means, said resetting signal producing means being enabled by said selected signal to thereafter produce said second signal upon the reception of a next following first reset signal.