Abstract: A system for the cyclical time-compression of a signal waveform, particularly applicable to displays. Continuous input data is temporarily stored, as in a recirculating memory, during the trace and retrace phases (B & A) of a processing or display operation. The stored data is subsequently read out in time-compressed form during the trace phase (B) of the cycle. The average rate at which data is read out of storage is faster than the average rate at which it is entered, the ratio of average readout rate to average entry rate being the compression ratio of the system and corresponding herein with the ratio of a full display sweep cycle to the trace portion of that cycle such that the initial waveform, time-compressed, is displayed in its entirety. In an illustrated embodiment, the data is entered into a recirculating memory at a rate resulting in apparent precession of the data in memory.

Abstract: An improved atrial synchronous heart pacer includes means for generating an atrio-ventricular (A-V) interval control signal of automatically variable duration, which duration is a function of the sensed atrial heart rate (i.e. P-wave rate). A timing circuit establishes a basic timing interval for the generation of ventricular stimulation pulses, which interval may be modified by the control of the A-V interval signal. The A-V interval control signal preferably comprises the output of a P-wave triggered monostable multivibrator. The time constants of the multivibrator's timing circuits are scaled such that operation within the heart-rate range of 55-150 beats per minute prevents full recovery of the multivibrator following each sensed atrial beat and generation of an A-V output pulse, resulting in an A-V output pulse whose duration is a function of the time since the preceding trigger (i.e. rate).

Abstract: In an implanted heart stimulating device of the demand type, test mode circuitry is arranged to cause the temporary generation of stimulation impulses at the demand-rate in the presence of naturally occurring heartbeats. The test mode circuitry may cause dependence of the heart-stimulation rate upon the level of the power source within the test mode or at least a portion of the test mode, but is arranged to provide a heart-stimulation rate independent of the level of the power source in the ordinary demand mode. The test mode circuitry is operative, through a relatively simple bias-modifying circuit, to force the pacer to generate at least several stimulating impulses at the demand-rate immediately following cessation of that portion of the test mode in which stimulation impulses are generated at a rate dependent upon the level of the power source. Subsequently, the pacer reverts to the ordinary (i.e., non-forced) demand mode.

Abstract: An improved battery for use with an implantable heart pacer. An implantable heart pacer provides stimulation to the heart of a patient and is normally battery-powered. A primary reason for pacer failure and resulting pacer replacement is failure in the battery or batteries. The present invention provides improved insulation against leakage between positive and negative electrodes of the implanted battery thus extending battery life and pacer life.

Abstract: A patient stimulating pacer electrode for use with heart pacers or other like devices. The electrode is constructed in a porous manner to have large surface area to reduce polarization losses while simultaneously having small overall dimensions for increasing stimulation current density and its ability to stimulate. Electrically conductive powdered metal is subjected to a sintering process to produce a porous conductive structure which is employed as the electrode. Conductive fluid from within the patient's body flows into the interstices of the overall small-dimensioned porous conductive structure; the resulting fluid-structure interface comprises a large surface area thereby reducing polarization losses.

Abstract: A compressed data display system. There is disclosed a system for recording over extended periods of time EKG and other vital signs of a patient and for automatically displaying the waveforms in a compressed and readily interpretable manner. The EKG waveform is recorded on looped paper supported by and/or wrapped around rotatable drum or drums which may have cylindrical shape. The EKG is recorded in helical or spiral fashion by simultaneously rotating the drum and transversely moving a galvanometer pen in the direction of the axis of rotation of the drum or cylinder. After the paper is removed, if it is a continuous or closed loop, it can be slit and opened into a single sheet. The recorded EKG waveforms are thus displayed compressed in a line-over-line manner and provide the physician with a clear picture of the patient's heart activity for extended periods of time.