Abstract: A multi-programmable ROM-less cardiac pacer employs an intermittent microprocessor turned ON and OFF by a pacer timer clockwise independent of the processor to time intervals preset by the processor. Sensed activity and external communications restart the processor with an interrupt request. Five antitachycardia mechanisms are externally programmable: programmed burst, burst rate scanning, automatic overdrive, programmed critically timed and critically timed scanning. In scanning mechanisms, the interval changes progressively until the tachycardia is terminated by a successful interval which is stored. Runaway protection is executed in the software. For telemetry, the pacer collects the following monitored pacing data over a programmable period of time: percent pacing, average rate, maximum rate, number of tachycardia episodes and maximum tachycardia duration.

Abstract: A multi-programmable ROM-less cardiac pacer employs an intermittent microprocessor turned ON and OFF by a pacer timer clockwise independent of the processor to time intervals preset by the processor. Sensed activity and external communications restart the processor with an interrupt request. Five antitachycardia mechanism are externally programmable: programmed burst, burst rate scanning, automatic overdrive, programmed critically timed and critically timed scanning. In scanning mechanisms, the interval changes progressively until the tachycardia is terminated by a successful interval which is stored. Runaway protection is executed in the software. For telemetry, the pacer collects the following monitored pacing data over a programmable period of time: percent pacing, average rate, maximum rate, number of tachycardia episodes and maximum tachycardia duration.

Abstract: A system is provided for detecting pacer mediated tachycardia. Atrial electrical signals (P waves) are sensed and ventricular electrical signals (R waves) are sensed. When a P wave is sensed, after a predetermined AV delay, a stimulating pulse is provided to the ventricle if no R wave is sensed during the AV delay. A threshold rate is selected for the sensed PP interval. If the ventrical has been stimulated and the threshold rate is exceeded for a selected number of PP intervals, the AV delay is increased by a predetermined time (delta). A determination is made whether the next sensed PP interval has increased by delta. If the next sensed PP interval has increased by delta, then pacer mediated tachycardia has occurred.In another embodiment, if the threshold rate is exceeded for a selected number of PP intervals, and the ventricle has been stimulated, then the sensed PP interval is measured and the AV delay is increased to a desired minimum PP interval minus the actual measured PP interval.

Abstract: A multi-programmable ROM-less cardiac pacer employs an intermittent microprocessor turned ON and OFF by a pacer timer clockwise independent of the processor to time intervals preset by the processor. Sensed activity and external communications restart the processor with an interrupt request. Five antitachycardia mechanisms are externally programmable: programmed burst, burst rate scanning, automatic overdrive, programmed critically timed and critically timed scanning. In scanning mechanisms, the interval changes progressively until the tachycardia is terminated by a successful interval which is stored. Runaway protection is executed in the software. For telemetry, the pacer collects the following monitored pacing data over a programmable period of time: percent pacing, average rate, maximum rate, number of tachycardia episodes and maximum tachycardia duration.

Abstract: A computer-controlled programmer having a user-interactive display is designed to control the parameters of a wide variety of implantable devices with different programming requirements. During programming, screen messages prompt the user to perform required actions by pressing lighted targets on the display screen. The programmer includes a console and a lightweight cable connected programming head. When the console is turned on, a self test routine automatically tests the programmer's batteries, memory banks and communications systems. For the communications test, the programmer employs a self-contained telemetry system which mimics the response of an implant. With certain implants, the programmer automatically changes programming options in response to information received from an implant as well as in response to selection of certain modes and lead configurations. The programmer software is designed to limit access to certain values and parameters which require the attendance of an authorized physician.