Implantable cardiac pacer with discontinuous microprocessor, programmable antitachycardia mechanisms and patient data telemetry

• US 4,726,380 A
• Filed: 10/15/1985
• Issued: 02/23/1988
• Est. Priority Date: 10/17/1983
• Status: Expired due to Term

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Telectronics Incorporated
• Inventors: Vollmann, William, Mumford, Van E.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US06/774,028
• Time in Patent Office: 861 Days
• Field of Search: 128/419 PG
• US Class Current: 607/15
• CPC Class Codes: A61N 1/3621 for treating or preventing abnormally high heart rate
• CPC Class Codes: A61N 1/37211 Means for communicating with stimulators
• CPC Class Codes: A61N 1/37264 Changing the program; Upgrading firmware

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.

Claims

1. An implantable cardiac stimulator, comprising:

an electrical terminal for connection to cardiac tissue;

sensing means connected to said terminal for producing a sense output indicative of cardiac activity;

output means connected to said terminal for applying a stimulation pulse via said terminal on command;

a volatile read/write random access memory containing selectable, programmable antitachycardia parameters representative of a sequence of stimulation commands and corresponding to either programmed burst, burst rate scanning, automatic overdrive, programmed critically timed, or critically timed scanning;

microprocessor means for executing the selected sequence of stimulation commands stored in said random access memory;

means for setting a programmable tachycardia threshold rate;

tachycardia detection means for issuing an arrhythmia output signal when the tachycardia threshold rate is exceeded a given number of times; and

antitachycardia means responsive to the arrhythmia output signal for causing the random access memory under control of the microprocessor means to apply the programmable sequence of stimulation commands to said output means.

2. The cardiac pacer of claim 1, further comprising means for resetting said tachycardia detection means each time said programmable sequence of stimulation commands is applied to said output means, whereby said antitachycardia means is repeatedly enabled until the tachycardia ceases.

3. The cardiac stimulator of claim 2, further comprising

means for automatically changing incrementally the antitachycardia means sequence each time the antitachycardia means is enabled until the tachycardia episode is ended.

4. The cardiac stimulator of claim 2, further comprising

memory means for automatically remembering the prescribed antitachycardia means sequence which was successful in terminating the tachycardia episode and using that sequence the next time the tachycardia detection means issues an arrhythmia signal indicative of a subsequent tachycardia episode.

5. The cardiac stimulator of claim 1, further comprising

means for automatically disabling said antitachycardia means after a preselected number of unsuccessful attempts to end a tachycardia episode by said antitachycardia means.

6. A cardiac pacer, comprising:

an electrical terminal for connection to cardiac tissue;

sense means connected to said terminal for producing a sense output indicative of cardiac activity;

output means connected to said terminal for issuing stimulation pulses via said terminal on command;

pacing logic means for applying an output command to said output means at a minimum rate in the absence of a sense output during a predetermined alert period;

a volatile read/write random access memory containing selectable, programmable antitachycardia parameters representative of a sequence of stimulation commands and corresponding to either programmed burst rate scanning, automatic overdrive, programmed critically timed, or critically timed scanning;

microprocessor means for executing the selected sequence of stimulation commands stored in said random access memory;

means for setting a predetermined tachycardia threshold rate;

tachycardia detection means responsive to a sense output rate in excess of the predetermined threshold rate for issuing an arrhythmia signal;

antitachycardia means responsive to said arrhythmia signal for causing the random access memory under control of the microprocessor to apply a prescribed sequence of output commands to said output means for terminating a tachycardia episode;

said random access memory including externally programmably accessible means for disabling said pacing logic from causing an output command without affecting the function of the tachycardia detection means and antitachycardia means; and

said externally programmably accessible means being capable of disabling said antitachycardia means without affecting said pacing logic means,

whereby the pacer can be externally programmed to serve as a cardiac pacer without antitachycardia response mechanisms, as a tachycardia monitor which responds to tachycardia episodes with the prescribed antitachycardia means, or both.

7. The pacer of claim 6, further comprising

said externally programmably accessible means being capable of disabling said antitachycardia means without affecting said tachycardia detection means,

whereby the pacer can be externally programmed to passively monitor tachycardia.

8. A cardiac pacer with tachycardia response comprising:

an electrical terminal for connection with cardiac tissue;

sensing means connected to said terminal for producing a sense output indicative of cardiac activity;

output means for applying stimulation pulses via said terminal on command;

a volatile read/write random access memory containing selectable, programmable antitachycardia parameters representative of a sequence of stimulation commands and corresponding to automatic overdrive;

microprocessor means for executing the selected sequence of stimulation commands stored in said random access memory;

means for setting a predetermined tachycardia threshold rate;

means for determining the average rate of a predetermined number of preceding sensed outputs;

tachycardia detection means responsive to said sense output exceeding the predetermined threshold rate for issuing an arrhythmia signal; and

antitachycardia means enabled by said arrhythmia signal for causing the random access memory under control of the microprocessor to apply a burst of a predetermined number of output pulse commands at a rate faster than the average rate of a predetermined number of preceding sensed outputs.