Evaluation system for cardiac stimulators

• US 3,920,005 A
• Filed: 09/28/1973
• Issued: 11/18/1975
• Est. Priority Date: 03/16/1972
• Status: Expired due to Term

• Current Assignee: John Thomas Gallagher, Peter P. Gombrich
• Original Assignee: John Thomas Gallagher, Peter P. Gombrich
• Inventors: Gombrich, Peter P., Gallagher, John T.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US05/401,648
• Time in Patent Office: 781 Days
• Field of Search: 128/2.5R,2.6R,2.1A,419P,419PG
• US Class Current: 600/510
• CPC Class Codes: A61B 5/0006 ECG or EEG signals
• CPC Class Codes: A61B 5/24 Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
• CPC Class Codes: A61B 5/7217 of noise originating from a therapeutic or surgical apparatus, e.g. from a pacemaker
• CPC Class Codes: A61N 1/3702 Physiological parameters A61N1/365 takes precedence; evoked response A61N1/371
• CPC Class Codes: Y10S 128/904 Telephone telemetry

Abstract

A system for evaluation of a cardiac stimulator connected to a patient, the system having means for detecting and differentiating between stimulation pulses and cardiac response pulses, means for determining rate of stimulation pulses and whether such rate falls within a predetermined calibration, and means for determining whether heart capture results from the stimulation pulses, all such means operative when the cardiac stimulator is in an asynchronous mode; the means being operative to determine whether the patient is dependent on cardiac stimulation pulses when the stimulator is in the demand mode. Also provided are means for transmitting the information to a remote receiver.

Claims

1. A system for cardiac stimulator evaluation, the system adapted to be connected to means for sensing stimulation pulses and cardiac pulses, comprising:

input means for receiving said sensed pulses;

first means for differentiating between stimulation pulses and cardiac pulses and including high bandpass filter means and low bandpass filter means each connected to the input means, the high bandpass filter means including means for passing frequencies in the range of stimulation pulses and the low bandpass filter means including means for passing frequencies in the range of cardiac pulses;

second means for detecting the rate of the stimulation pulses;

third means for detecting heart captures due to stimulation pulses;

means connecting the input means to the first means;

means connecting the first means to the second and third means; and

fourth means connected to the second and third means and responsive to signals therefrom for indicating the status of operation of the stimulator being evaluated.

2. The apparatus of claim 1 in which:

the means for passing frequencies in the high bandpass filter means is centered around 1Khz; and

the means for passing frequencies in the low bandpass filter means is centered around 10hz.

3. The apparatus of claim 1 in which the input means includes:

amplifier means connected to the filter means.

4. The apparatus of claim 1 including:

modulation means connected to the first means and including means for providing a carrier frequency modulated to a first frequency in response to a stimulation pulse and modulated to a second frequency in response to a cardiac pulse;

first transmission means connected to the modulation means for transmitting the carrier frequency and the first and second modulated frequencies;

second transmission means connected to receive the carrier frequency and the first and second modulated frequencies;

demodulator means connected to the second transmission means and having means for detecting the first and second modulated frequencies for providing first and second output signals representative of, respectively, stimulation pulses and cardiac pulses; and

means connected to the demodulator means for receiving the output signals therefrom, and selectively connectable to electrocardiogram means and rate interval counter means.

5. The apparatus of claim 4 including:

oscillator means connected to the fourth means and responsive to signals therefrom indicative of the status of operation of the stimulator being evaluated;

means connecting the oscillator means to the modulation means;

the modulation means including means for modulating the carrier frequency to a third frequency in response to an input from the oscillator means representative of the status of operation of the stimulator being evaluated;

the first and second transmission means including means for, respectively, transmitting and receiving the third modulated frequency;

the demodulator means including means for detecting the third modulated frequency for providing third output signals representative of the status of the stimulator being evaluated; and

indicator means connected to the demodulator means and responsive to signals therefrom for indicating the status of the stimulator being evaluated.

6. The apparatus of claim 4 including:

carrier frequency detecting means connected to the second transmission means for detecting and indicating the presence and absence of the carrier frequency.

7. The apparatus of claim 4 including:

selectively operable call back oscillator means;

means connecting the call back oscillator means to the second transmission means for transmission of a call back signal to the first transmission means; and

call back receiver means connected to the first transmission means for detecting and indicating the presence or absence of a call back signal.

8. A system for cardiac stimulator evaluation, the system adapted to be connected to means for sensing stimulation pulses and cardiac pulses, comprising:

input means for receiving said sensed pulses;

first means for differentiating between stimulation pulses and cardiac pulses and including high bandpass filter means and low bandpass filter means each connected to the input means, the high bandpass filter means including means for passing frequencies in the range of stimulation pulses and the low bandpass filter means including means for passing frequencies in the range of cardiac pulses;

second means for detecting the rate of the stimulation pulses;

third means for detecting heart captures due to stimulation pulses;

means connecting the input means to the first means;

means connecting the first means to the second and third means; and

fourth means connected to the second and third means and responsive to signals therefrom for indicating the status of operation of the stimulator being evaluated;

said second means including rate detection means for detecting the time intervals between succeeding stimulation pulses;

adjustable calibration means for providing a calibration window for a desired stimulation pulse rate, means connected to the rate detection means and the calibration means for comparing the time intervals to the calibration window and including means for providing a signal to the fourth means.

9. A system for cardiac stimulator evaluation, the system adapted to be connected to means for sensing stimulation pulses and cardiac pulses, comprising:

input means for receiving said sensed pulses;

first means for differentiating between stimulation pulses and cardiac pulses;

second means for detecting the rate of the stimulation pulses;

third means for detecting heart captures due to stimulation pulses;

means connecting the input means to the first means;

means connecting the first means to the second and third means; and

fourth means connected to the second and third means and responsive to signals therefrom for indicating the status of operation of the stimulator being evaluated;

said third means including capture detector means responsive to a stimulation pulse for thereafter detecting any succeeding cardiac pulse that occurs within a first predetermined time interval following the stimulation pulse and means for counting all such detected cardiac pulses which occur during a second longer predetermined time interval, and for providing a signal to the fourth means when the number of such detected cardiac pulses reaches a predetermined total.

10. The apparatus of claim 9 in which:

the first predetermined time interval is 50 milliseconds.

11. The apparatus of claim 9 in which:

the second predetermined time interval is 15 seconds.

12. The apparatus of claim 9 in which:

the predetermined total is at least three.

13. The apparatus of claim 9 including:

timing means connected to the capture detector means, and including means responsive to a stimulation pulse for commencing the second predetermined time interval.

14. A system for cardiac stimulator evaluation, the system adapted to be connected to means for sensing stimulation pulses and cardiac pulses, comprising:

input means for receiving said sensed pulses;

first means for differentiating between stimulation pulses and cardiac pulses and including high bandpass filter means and low bandpaSs filter means each connected to the input means, the high bandpass filter means including means for passing frequencies in the range of stimulation pulses and the low bandpass filter means including means for passing frequencies in the range of cardiac pulses;

second means for detecting the rate of the stimulation pulses;

third means for detecting heart captures due to stimulation pulses;

means connecting the input means to the first means;

means connecting the first means to the second and third means and fourth means connected to the second and third means and responsive to signals therefrom for indicating the status of operation of the stimulator being evaluated;

fifth means for counting a predetermined minimum number of stimulation pulses in a predetermined period of time;

sixth means connected to the fifth means and responsive to signals therefrom for indicating the status of operation of the stimulator being evaluated;

switch means having first and second switch positions;

means operative when the switch means is in the first switch position for disabling the fifth and sixth means and enabling the fourth means; and

means operative when the switch means is in the second switch position for disabling the fourth means and enabling the fifth and sixth means.

15. The apparatus of claim 14 including:

modulation means connected to the first means and including means for providing a carrier frequency modulated to a first frequency in response to a stimulation pulse and modulated to a second frequency in response to a cardiac pulse;

oscillator means connected to the fourth means and responsive to signals therefrom indicative of the status of operation of the stimulator being evaluated;

means connecting the sixth means to the oscillator means;

means connecting the oscillator means to the modulation means, the modulation means including means for modulating the carrier frequency to a third frequency in response to an input from the oscillator means representative of the status of operation of the stimulator being evaluated;

first transmission means connected to the modulation means for transmitting the carrier frequency and the first, second and third modulated frequencies;

second transmission means connected to receive the carrier frequency and the first, second and third modulated frequencies;

demodulator means connected to the second transmission means and having means for detecting the first, second and third modulated frequencies for providing first and second output signals representative of respectively, stimulation pulses and cardiac pulses and for providing third output signals representative of the stimulator being evaluated;

indicator means connected to the demodulator means and responsive to signals therefrom for indicating the status of the stimulator being evaluated; and

further means connected to the demodulator means for receiving the output signals therefrom and selectively connectable to electrocardiogram means and rate interval counter means.

16. The apparatus of claim 15 including:

mode oscillator means connected between the switch means and the transmission means and operable to provide an output to the transmission means when the switch means is in one of the first or second switch positions;

mode detection means connected between the second transmission means and the indicator means for providing mode information to the indicator means.

17. The apparatus of claim 14 in which:

the predetermined period of time is 15 seconds.

18. The apparatus of claim 14 in which:

the predetermined minimum number is two.

19. A system for evaluating a cardiac stimulator operating in an asynchronous mode or a demand mode, the system adapted to be connected to means for sensing stimulation pulses and cardiac pulses, comprising:

input means for receiving said sensed pulses;

first frequency filter means for passing frequency signals from stimulation pulses;

second frequency filter means for passing frequency signals from cardiac pulses;

rate detector means cOnnected to the first filter means for detecting the rate of stimulation pulses;

capture detector means connected to the first and second filter means for detecting captures that comprise a cardiac pulse which follows a stimulation pulse within a first predetermined period of time;

counter means connected to the capture detector means for counting the captures which occur within a second predetermined period of time;

first indicator means connected to the rate detector means and the counter means and including means responsive to signals therefrom for providing visual stimulator status indications;

timer means connected to the capture detector means and the first filter means, and responsive to a stimulator pulse for enabling the capture detector means for the second predetermined period of time;

further detector means connected to the timer means;

second indicator means connected to the further detector means and including means responsive to signals therefrom during said second predetermined period of time for providing visual stimulator status indications;

switch means selectably adjustable to an asynchronous mode position and a demand mode position, the switch means including means operable in the asynchronous mode position for enabling the first indicator means and disabling the second indicator means and the further detector means, and the switch means including means operable in the demand mode position for disabling the first indicator means and enabling the second indicator means, the further detector means and means in the timer means for allowing stimulation pulses to reset the timer means during the second predetermined time period.

20. The system of claim 19 including:

modulation means connected to the first and second filter means;

indicator oscillator means connected to the first indicator means, the further detector means and the modulation means;

first transmission means;

first acoustic coupler means connected between the modulation means and the transmission means;

mode oscillator means connected between the switch means and the first coupler means;

second transmission means connected to the first transmission means;

demodulation means;

second acoustic coupler means connected between the second transmission means and the demodulation means;

remote indicator means responsive to demodulated signals from the demodulator means for providing visual stimulator status indications;

indicator filter means connected between the demodulation means and the remote indicator means; and

mode filter means connected between the second coupler means and the remote indicator means.

21. The apparatus of claim 20 including:

first call back indicator means; and

carrier frequency detection means connected between the second acoustic coupler and the first call back indicator means.

22. The apparatus of claim 20 including:

selectively operable call back oscillator means connected to the second acoustic coupler means;

second call back indicator means; and

call back receiver means connected between the first acoustic coupler means and the second call back indicator means.

23. The apparatus of claim 20 including;

means connected to the demodulator means and selectively connectable to electrocardiogram means and rate interval computer means.