Electronic pacemaker testing device

• US 5,209,228 A
• Filed: 10/26/1990
• Issued: 05/11/1993
• Est. Priority Date: 10/26/1990
• Status: Expired due to Fees

• Current Assignee: Allegheny-Singer Research Institute
• Original Assignee: Allegheny-Singer Research Institute
• Inventors: Moeller, Frederick W., Rapp, Timothy E., Lubinski, Mark A., Coast, Douglas A., Cano, Gerald G.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US07/605,851
• Time in Patent Office: 928 Days
• Field of Search: 128/419 PT
• US Class Current: 607/27
• CPC Class Codes: A61N 1/3706 Pacemaker parameters stimulation threshold A61N1/371

Abstract

An electronic test instrument for rapid comprehensive verification of correct operation of medical pacers. This portable microprocessor-based test instrument includes a device for measuring and displaying pacer characteristics including pacing rate, pulse duration, pulse amplitude, sensitivity, sensed refractory interval, stimulus refractory interval, atrio-ventricular delay, D.C. leakage, susceptibility to A.C. interference, frequency response and battery drain. The test instrument includes a device for selecting each test and entering associated parameters, a device to convert the analog pacer pulses to digital values for detection and measurement, a device to generate variable amplitude test waveforms and apply them to a medical pacer at a specified rate or at a specified delay from a previous pacer pulse or with a specified delay between two test waveforms and a device for displaying test results. Sensed and stimulus refractory intervals are determined in minimal time using a unique binary search strategy which continually halves the range of possible refractory intervals until the desired interval is determined.

Claims

1. A self-contained, portable medical pacing unit tester capable of quickly and comprehensively testing medical pacing units comprising:

(a) a means for transferring signals between said tester and said pacing unit which is being tested by said tester;

(b) a data entry device, said data entry device further comprising a means to select at least one medical pacing unit test and to input one or more medical pacing unit parameters where said parameters are necessary to perform said selected medical pacing unit test;

(c) a means for timing intervals associated with performing said pacing unit test;

(d) a means to generate a set of test signals to be sent to said pacing unit when required for said medical pacing unit test, said means for generating said set of test signals further comprising a microcomputer and a digital/analog converter wherein said microprocessor further comprises a means for generating a series of digital values corresponding to at least one analog test waveform appropriate for said selected medical pacing unit test and a means for transferring said digital values to said digital/analog converter, said digital/analog converter further including a means for generating at least one corresponding analog test waveform and a means for transferring said analog test waveform to said pacing unit;

(e) a means to analyze a set of pacing signals received by said tester from said pacing unit, wherein said set of pacing signals generated by said pacing unit comprises at least one analog waveform whereupon said means for analyzing further comprises an analog/digital converter for converting said analog waveform to a series of digital values corresponding to said analog waveform, and a microcomputer for analyzing said digital values with programming appropriate to said selected medical pacing unit test; and

(f) a means to display result(s) of said analysis;

(g) wherein said means to select said medical pacing unit test includes a means to select a stimulus refractory interval test wherein said means to select said stimulus refractory interval test further includes;

(1) a means to generate at least one test waveform and transmit said test waveform to said pacing unit;

(2) a means to determine an interval between successive of said pacing signals generated by said pacing unit, wherein each of said pacing signals initially form an analog waveform of a pacing pulse which is converted to proportional digital values by said tester;

(3) a means to control voltage amplitude of said test waveform;

(4) a means to position said test waveform at a specific interval after the generation of one of said one or more pacing signals generated by said pacing unit;

(5) a means to measure an interval between successive pacing signals generated by said pacing unit, said interval now containing said test waveform of step (4) generated by said tester;

(6) a means to compare said interval of step (5) with said interval of step (2) to determine whether or not said positioned test waveform was detected by said pacing unit, said detection by said pacing unit being indicated by an increase of said interval of step (5) over said interval of step (2);

(7) a means to repeat steps (4)-(6), continually repositioning said test waveform pursuant to a binary search strategy to calculate an interval after generation of said pacing signals generated by said pacing units when demand circuitry of said pacing unit is first able to sense said test waveform.

2. The tester as defined in claim 1, further including a means to repeat said steps (4)-(6) for each positioning of said positioned test waveform to very the results obtained.

3. A self-contained, portable medical pacing unit tester capable of quickly and comprehensively testing medical pacing units comprising:

(a) a means for transferring signals between said tester and said pacing unit which is being tested by said tester;

(b) a data entry device, said data entry device further comprising a means to select at least one medical pacing unit test and to input one or more medical pacing unit parameters where said parameters are necessary to perform said selected medical pacing unit test;

(c) a means for timing intervals associated with performing said pacing unit test;

(d) a means to generate a set of test signals to be sent to said pacing unit when required for said medical pacing unit test, said means for generating said set of test signals further comprising a microcomputer and a digital/analog converter wherein said microprocessor further comprises a means for generating a series of digital values corresponding to at least one analog test waveform appropriate for said selected medical pacing unit test and a means for transferring said digital values to said digital/analog converter, said digital/analog converter further including a means for generating at least one corresponding analog test waveform and a means for transferring said analog test waveform to said pacing unit;

(e) a means to analyze a set of pacing signals received by said tester from said pacing unit, wherein said set of pacing signals generated by said pacing unit comprises at least one analog waveform whereupon said means for analyzing further comprises an analog/digital converter for converting said analog waveform to a series of digital values corresponding to said analog waveform, and a microcomputer for analyzing said digital values with programming appropriate to said selected medical pacing unit test; and

(f) a means to display result(s) of said analysis;

(g) wherein said means to select said medical pacing unit test includes a means to select a stimulus refractory interval test wherein said means to select said sensed refractory interval test further includes;

(1) a means to generate at least one test waveform and transmit said test waveform to said pacing unit;

(2) a means to determine an interval between a first pacing signal and a second consecutive pacing signal generated by said pacing unit, wherein each of said first and said second pacing signals initially form an analog waveform of a pacing pulse which is converted to proportional digital values by said tester;

(3) a means to control voltage amplitude of said one or more test waveforms;

(4) a means to position said test waveform at a specific interval after generation of a pacing signal generated by said pacing unit;

(5) a means to position a second test waveform at a specific interval after generation of said positioned test waveform of step (4);

(6) a means to measure an interval between said test waveform of step (4) and a next occurring pacing signal after said pacing signal of step (4) of said pacing signals generated by said pacing unit;

(7) a means to compare said interval of step (6) with said interval of step (2), to determine whether said second test waveform of step (5) was sensed by said pacing unit;

sensing by said pacing unit being indicated by an increase of said interval of step (6) over said interval of step (2);

(8) a means to repeat steps (4)-(7), continually repositioning said second test waveform of step (5), pursuant to a binary search strategy to calculate an interval when demand circuitry of said pacing unit is first able to sense said second test waveform of step (5).

4. The tester as defined in claim 3, further including a means to repeat said steps (4)-(7) for each positioning of said second test waveform of step (5), to verify the results obtained.

5. A method for quickly and comprehensively testing medical pacing units utilizing a self-contained, portable medical pacing unit tester comprising the steps of:

(a) transferring signals between said tester and said pacing unit which is being tested by said tester;

(b) selecting at least one medical pacing unit test and inputting at least one medical pacing unit parameter where said parameter is necessary to perform said selected medical pacing unit test;

(c) timing intervals associated with performing said pacing unit test;

(d) generating a set of test signals to be sent to said pacing unit when required for said medical pacing unit test, wherein the step of generating said set of test signals includes a microcomputer and a digital/analog converter, said microprocessor generating a series of digital values corresponding to at least one analog test waveform appropriate for said selected medical pacing unit test and transferring said digital values to said digital/analog converter, said digital/analog converter generating at least one corresponding analog test waveform and transferring said analog test waveform to said pacing unit;

(e) analyzing a set of pacing signals received by said tester and generating from said pacing unit, said set of pacing signals being generated by said pacing unit and comprising at least one analog waveform, said analyzing further comprising the steps of converting said analog waveforms to a series of digital values corresponding to said analog waveform with an analog/digital converter, and analyzing said digital values with a microcomputer by installing on said microcomputer programming appropriate to said selected medical pacing unit test; and

(f) displaying result(s) of said analysis;

(g) wherein said selecting step (b) includes a means for selecting a stimulus refractory interval test wherein said stimulus refractory interval test includes;

(1) generating at least one test waveform and transmitting said test waveform to said pacing unit;

(2) determining an interval between successive of said pacing signals generated by said pacing unit, wherein each of said pacing signals initially form an analog waveform of a pacing pulse which is converted to proportional digital values by said tester;

(3) controlling voltage amplitude of said one or more test waveforms;

(4) positioning said test waveform at a specific interval after the generation of one of said pacing signals generated by said pacing unit;

(5) measuring an interval between successive pacing signals generated by said pacing unit, said interval now containing said test waveform of step (4) generated by said tester;

(6) comparing said interval of step (5) with said interval of step (2) to determine whether or not said positioned test waveform was detected by said pacing unit, said detection by said pacing unit being indicated by an increase of said interval of step (5) over said interval of step (2);

(7) repeating steps (4)-(6), continually repositioning said test waveform pursuant to a binary search strategy to calculate an interval after generation of said pacing signals generated by said pacing units when demand circuitry of said pacing unit is first able to sense said test waveform.

6. The method of claim 5, wherein said steps (4)-(6) are repeated at least one time for each positioning of said positioned test waveform to verify the results obtained.

7. A method for quickly and comprehensively testing medical pacing units utilizing a self-contained, portable medical pacing unit tester comprising the steps of:

(a) transferring signals between said tester and said pacing unit which is being tested by said tester;

(b) selecting at least one medical pacing unit test and inputting at least one medical pacing unit parameter where said parameter is necessary to perform said selected medical pacing unit test;

(c) timing intervals associated with performing said pacing unit test;

(d) generating a set of test signals to be sent to said pacing unit when required for said medical pacing unit test, wherein the step of generating said set of test signals includes a microcomputer and a digital/analog converter, said microprocessor generating a series of digital values corresponding to at least one analog test waveform appropriate for said selected medical pacing unit test and transferring said digital values to said digital/analog converter, said digital/analog converter generating at least one corresponding analog test waveform and transferring said analog test waveform to said pacing unit;

(e) analyzing a set of pacing signals received by said tester and generating from said pacing unit, said set of pacing signals being generated by said pacing unit and comprising at least one analog waveform, said analyzing further comprising the steps of converting said analog waveform to a series of digital values corresponding to said analog waveform with an analog/digital converter, and analyzing said digital values with a microcomputer by installing on said microcomputer programming appropriate to said selected medical pacing unit test; and

(f) displaying result(s) of said analysis;

(g) wherein said selecting step (b) includes a means for selecting a sensed refractory interval test wherein said sensed refractory interval test includes;

(1) generating at least one test waveform and transmitting said test waveform to said pacing unit;

(2) determining an interval between a first pacing signal and a second consecutive pacing signal generated by said pacing unit, wherein each of said first and said second pacing signals initially forms an analog waveform of a pacing pulse which is converted to proportional digital values by said tester;

(3) controlling voltage amplitude of said one or more test waveforms;

(4) positioning said test waveform at a specific interval after the generation of a pacing signal generated by said pacing unit;

(5) positioning a second test waveform at a specific interval after generation of said positioned test waveform of step (4);

(6) measuring an interval between said test waveform of step (4) and a next occurring pacing signal after said pacing signal of step (2) generated by said pacing unit;

(7) comparing said interval of step (6) with said interval of step (2), to determine whether said second test waveform of step (5) was sensed by said pacing unit;

sensing by said pacing unit being indicated by an increase of said interval of step (2) over said interval of step (2);

(8) repeating steps (2)-(7), continually repositioning said second test waveform of step (5), pursuant to a binary search strategy to calculate an interval when demand circuitry of said pacing unit is first able to sense said second test waveform of step (5).

8. The method of claim 7, wherein said steps (4)-(7) are repeated at least one time for each positioning of said second test waveform of step (5), to verify the results obtained.

9. A method for measuring the stimulus refractory period of a medical pacer using an efficient binary search strategy comprising the steps of:

(a) sensing the occurrence of output pulses from said medical pacer;

(b) measuring a first interval between successive output pulses of said medical pacer;

(c) initializing minimum and maximum range variables for the stimulus refractory period to be zero and said first interval, respectively;

(d) setting a test waveform delay variable equal to said minimum range variable plus one half of the difference between said maximum range variable and said minimum range variable;

(e) applying a test waveform to said medical pacer following the occurrence of an output pulse of said medical pacer at a delay determined by said test waveform delay variable;

(f) measuring a second interval between successive output pulses of said medical pacer, said second interval now containing said test waveform;

(g) comparing said second interval to said first interval to determine if said second interval is greater than said first interval, indicating that said test waveform was sensed by said medical pacer;

(h) adjusting said minimum and said maximum range variables according to the result of step (g);

if said test waveform was sensed, then said maximum range variable is set to said test waveform delay variable, otherwise, said minimum range variable is set to said test waveform delay variable;

(i) comparing said maximum range variable and said minimum range variable to determine if their difference is equal to or less than a predetermined accuracy value;

if so then the stimulus refractory period is reported as the current value of said test waveform delay variable, otherwise, repeat steps (d)-(i).

10. The method as in claim 9, wherein steps (e)-(g) are repeated at least one time during each iteration to verify the comparison of step (g) before proceeding with step (h).

11. A method for measuring the sensed refractory period of a medical pacer using an efficient binary search strategy comprising the steps of:

(a) sensing the occurrence of output pulses from said medical pacer;

(b) measuring a first interval between successive output pulses of said medical pacer;

(c) initializing minimum and maximum range variables for the stimulus refractory period to be zero and said first interval, respectively;

(d) applying a first test waveform to said medical pacer following the occurrence of an output pulse of said medical pacer at a delay greater than the stimulus refractory period of said medical pacer;

(e) setting a test waveform delay variable equal to said minimum range variable plus one half of the difference between said maximum range variable and said minimum range variable;

(f) applying a second test waveform to said medical pacer immediately following the said first test waveform at a delay determined by said test waveform delay variable;

(g) measuring a second interval between said first test waveform and the next successive output pulse of said medical pacer, said second interval now containing said second test waveform;

(h) comparing said second interval to said first interval to determine if said second interval is greater than said first interval, indicating that said second test waveform was sensed by said medical pacer;

(i) adjusting said minimum and said maximum range variables according to the result of step (g);

if said second test waveform was sensed, then said maximum range variable is set to said test waveform delay variable, otherwise, said minimum range variable is set to said test waveform delay variable;

(j) comparing said maximum range variable and said minimum range variable to determine if their difference is equal to or less than a predetermined accuracy value;

if so then the sensed refractory period is reported as the current value of said test waveform delay variable, otherwise, repeat steps (d)-(j).

12. The method as in claim 11, wherein steps (d)-(h) are repeated at least one time during each iteration to verify the comparison of step (h) before proceeding with step (i).

13. Apparatus for measuring the stimulus refractory period of a medical pacer comprising:

(a) means for sensing the occurrence of output pulses from said medical pacer;

(b) means for measuring a first interval between successive output pulses of said medical pacer;

(c) means for initializing minimum and maximum range variables for the stimulus refractory period to be zero and said first interval, respectively;

(d) means for setting a test waveform delay variable equal to said minimum range variable plus one half of the difference between said maximum range variable and said minimum range variable;

(e) means for producing a test waveform and applying said test waveform to said medical pacer following the occurrence of an output pulse of said medical pacer at a delay determined by said test waveform delay variable;

(f) means for measuring a second interval between successive output pulses of said medical pacer, said second interval now containing said test waveform;

(g) means for comparing said second interval to said first interval to determine if said second interval is greater than said first interval, indicating that said test waveform was sensed by said medical pacer;

(h) means for adjusting said minimum and said maximum range variables according to the result of step (g);

if said test waveform was sensed, then said maximum range variable is set to said test waveform delay variable, otherwise, said minimum range variable is set to said test waveform delay variable;

(i) means for comparing said maximum range variable and said minimum range variable to determine if their difference is greater than a predetermined accuracy value;

(j) means to repeat steps (d)-(i) if said difference in step (i) is greater than said predetermined accuracy value;

(k) means to display the current test waveform delay variable as the refractory interval.

14. Apparatus for measuring the sensed refractory period of a medical pacer comprising:

(a) means for sensing the occurrence of output pulses from said medical pacer;

(b) means for measuring a first interval between successive output pulses of said medical pacer;

(c) means for initializing minimum and maximum range variables for the stimulus refractory period to be zero and said first interval, respectively;

(d) means for producing a first test waveform and applying said first test waveform to said medical pacer following the occurrence of an output pulse of said medical pacer at a delay greater than the stimulus refractory period of said medical pacer;

(e) means for setting a test waveform delay variable equal to said minimum range variable plus one half of the difference between said maximum range variable and said minimum range variable;

(f) means for producing a second test waveform and applying said second test waveform to said medical pacer immediately following the said first test waveform at a delay determined by said test waveform delay variable;

(g) means for measuring a second interval between said first test waveform and the next successive output pulse of said medical pacer, said second interval now containing said second test waveform;

(h) means for comparing said second interval to said first interval to determine if said second interval is greater than said first interval, indicating that said second test waveform was sensed by said medical pacer;

(i) means for adjusting either said minimum or said maximum range variables according to the result of step (g);

if said second test waveform was sensed, then said maximum range variable is set to said test waveform delay variable, otherwise, said minimum range variable is set to said test waveform delay variable;

(j) means for comparing said maximum range variable and said minimum range variable to determine if their difference is greater than a predetermined accuracy value;

(k) means to repeat steps (d)-(j) if said difference in step (j) is greater than said predetermined accuracy value;

(l) means for displaying the current value of said test waveform delay variable.