Abstract: A biomedical system such as a pacemaker system having an implantable pacemaker and external apparatus, with communications capability for communicating between the implanted device and the external apparatus, characterized by the implanted device having means for cyclically transmitting event and device timing data representative of each prior device interval, the external apparatus having means for receiving and storing the data and for graphically constructing a graphic output representative of the timing and event information over a plurality of device cycles. Graphic output preferably includes a linear timing graph representative of timing functions of the implanted device.

Abstract: A programmable dual chamber cardiac pacemaker is provided which provides improved means for responding to sensed high atrial rates. The pacemaker monitors the sensed high atrial rates and determines whether they are physiological or not, and automatically controls the operative atrial refractory period as a function of whether or not the atrial rate is physiological. The pacemaker is permitted to go into a Wenckebach mode of operation only when it is determined that a sensed high atrial rate is physiological, and that under other conditions will automatically go into a block mode of operation.

Abstract: An improved cardiac pacemaker adapted to be programmed into one of a plurality of given modes of operation, including dual chamber modes, and in particular synchronous operation for pacing the patient's ventricle following detection of natural atrial heartbeats. The pacemaker has means for monitoring the time relationship between delivered ventricular stimulus pulses and next succeeding atrial heartbeats, for determining the occurrence of pacemaker induced retrograde P waves, or pacemaker caused tachycardia. The timing, and thus the rate of sensed P signals is processed to determine the desirability of establishing a special P sense window for looking for the occurrence of P signals at rates above a normal maximum operating rate, in which event the stability of the V-A timing is monitored in accordance with predetermined criteria to determine the existence of pacemaker mediated tachycardia, which may be broken up by skipping a ventricular stimulus.

Abstract: A physiological device adapted for implantation in a human patient, e.g. a cardiac pacemaker or muscle stimulator, characterized by having programmable means for generating data and assembling same for presentation of one or more histograms. The implanted device has circuitry for registering the occurrence of sensed or evoked events, as well as device operating events such as cycles of operation, and means, preferably software control of a microprocessor, for classifying registered events into respective classes of one or more parameters associated with the events and for accumulating counts of events for each such class. The system also includes external apparatus for communicating programmed instructions to the device, whereby histogram selection and histogram classes are programmed, and for receiving the histogram data transmitted from the implanted device and displaying it in a convenient histogram form. Time based histograms are also generated, utilizing a software clock for continuously tracking time.

Abstract: A programmable pacemaker apparatus having a microprocessor and means for receiving program information from an external source, means for generating and delivering stimulus signals and means for sensing the occurrence of natural heartbeats in a patient, and having a battery source powering the apparatus, said microprocessor being combined with program instructions stored in memory for controlling the operation of said pacemaker, comprising controller circuit means external to said microprocessor and interconnected therewith for controlling the operating state of said microprocessor, said controller means having occurrence means for determining the occurrence of given events. The controller means further comprises means for stopping operation of the microprocessor on command from the microprocessor and for starting operation of the microprocessor upon determination of one of said events, whereby the microprocessor normally is on less than about 25% of the time.