Abstract: A microprocessor-controlled implantable programmable stimulator includes a pulse generator external to the microprocessor for producing stimulation output pulses to multiple electrodes. A single chip microprocessor accompanied by a ROM implements a stored program data processing system which sets various latches to establish the desired pulse parameters. Externally transmitted parameter data is decoded by the processing system, confirmed by two-way telemetry and loaded into control registers. The microprocessor obtains corresponding stored values from parameter tables in the ROM, and then sets the amplitude, rate and width latches. The pulse rate and width latches preset discrete rate and width down counters operated by respective slow and fast clocks. To conserve power, the fast clock is enabled only briefly each time the rate counter times out when it is time to issue an output pulse. When running, the fast clock replaces the slow clock input to the microprocessor.

Abstract: A microprocessor-controlled implantable programmable stimulator includes a pulse generator external to the microprocessor for producing stimulation output pulses to multiple electrodes. A microprocessor implements a stored program data processing system which sets latches to establish pulse parameters. Externally transmitted parameter data is decoded by the processing system, confirmed by two-way telemetry and loaded into control registers. The microprocessor obtains corresponding stored values from parameter tables in a ROM, and then sets amplitude, rate and width latches. The pulse rate and width latches preset separate counters operated by respective slow and fast clocks. To conserve power, the fast clock is enabled only briefly each time the rate counter times out. When running, the fast clock replaces the slow clock input to the microprocessor.

Abstract: The cardiac pacer disclosed herein responds to a premature heartbeat by first digitally measuring the time interval between a pair of successive sensed heartbeats and establishing an escape interval for stimulation which is shorter than the measured heartbeat interval. Pacing at this shorter escape interval enables the pacer to capture and control the heartbeat rate. By repeatedly incrementing the digital value representing the escape value on successive stimulated heartbeats, the heart is then caused to slow down until a preselected desired rate is established. Preferably, the sensing and timing between heartbeats continues during the slowdown process so that, if, at any time, a natural heartbeat occurs earlier than the stimulation pulse at the then extant escape interval, the escape interval is reset to a shorter time so that capture will be re-established.