Method and apparatus for holter recorder with high resolution signal averaging capability for late potential analysis

• US 5,205,295 A
• Filed: 08/18/1992
• Issued: 04/27/1993
• Est. Priority Date: 06/03/1991
• Status: Expired due to Term

• Current Assignee: Spacelabs Healthcare LLC (OSI Systems Incorporated)
• Original Assignee: Del Mar Avionics
• Inventors: Del Mar, Bruce, Cherry, Isaac R.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US07/932,907
• Time in Patent Office: 252 Days
• Field of Search: 128/696, 128/710, 128/711
• US Class Current: 600/524
• CPC Class Codes: A61B 5/337 Playback at speeds other than the recording speed
• CPC Class Codes: A61B 5/7232 involving compression of the physiological signal, e.g. to extend the signal recording period

Abstract

A method and apparatus for an ambulatory electrocardiographic monitoring system for recording, detection, measurement, analysis and plotting of high resolution electrocardiographic data having a modified Holter recorder that performs digital signal averaging of selected signals as well as storing for future playback all ECG beats. The digitally signal averaged beats are correlated with a previously defined correlation coefficient yielding summated results that have eliminated nonrepetitive noise to less than a microvolt. By real time averaging approximately 1000 beats during a 10 to 15 minute period and digitally storing the averaged data, micropotential averaging can be performed several times per hour for up to 24-hours. Analog recordings are precalibrated for accurate amplitude representation as well as providing an option for standard one millivolt calibration pulses at the beginning of the tape. Digital recordings are precalibrated relative to the acceptable levels without the use of a calibration signal. The recordings are downloaded to analysis systems at high speeds. If the recordings are analog they are digitized at a sufficiently high enough resolution to permit analysis of micropotentials. All recorded data is transferred to computer memory and hard disk for further review by the analysis system.

Claims

1. A long term ambulatory (Holter) based electrocardiographic (ECG) system for recording and analyzing bioelectric signals of the human heart comprising:

electrode means, consisting of a plurality of electrocardiographic (ECG) electrodes adapted for placement on a human patient, for detecting bioelectric signals of the human heart and generating, therefrom, an analog signal;

recorder means electrically connected to said plurality of electrodes for making a real time recording of bioelectric signals detected by said electrodes, said recorder means having a plurality of data channels such that there is at least one data channel for each of said ECG electrodes;

storage means contained within said recorder means;

digitizing means contained within said recorder for converting said analog signals into a series of digital signals representative of bioelectric signals of the human heat;

analysis means contained within said recorder means for taking a sample form said series of digital signals and computing, therefrom, a signal average for each of said ECG data channels.

2. The invention of claim 1 wherein at least one of said data channels is used to record said summations of said signal averages for each channel.

5. The invention of claim 1 wherein said digitizing means contains high resolution means for performing high resolution sampling and digitizing.

6. The invention of claim 1 wherein said storage means is selected from the group consisting of:

(1) analog magnetic tape;

(2) digital audio tape (DAT);

(3) solid state recording (SSR) with limited memory;

(4) solid state memory recording with extended memory;

(5) rotating magnetic media;

(6) rotating optical media;

(7) rotating magneto-optical media; and

(8) removable memory card media.

7. The invention of claim 1 wherein said analysis means further comprises a microprocessor having available memory means to store instructions for said microprocessor, said microprocessor executing instructions with said memory means to perform said sampling and signal averaging under control of a microcode program embedded in a nonvolatile memory source as well as placing said summated signal averaged signals in a RAM source prior said placing onto said storage means.

8. The invention of claim 1 further including an ECG analysis computer having playback means for playing back all recorded ECG signals and summated signal averaged signals to said ECG analysis computer, said playback means having high speed means to play back recordings at a speed many times the real time recording speed.

9. The invention of claim 8 further including means for storing all recorded signals in a digital format in a storage area, said storage consisting of an area of memory or a disk storage device.

10. The invention of claim 1 wherein said analysis means further includes means to correlate coefficient to provide a basis for eliminating nonrepetitive noise and irregular beats.

3. The invention of 1, wherein said analysis means includes acquisition means to acquire said sample from a predetermined time period.

4. The invention of claim 3, wherein said acquisition means acquires said sample in response to patient activation.

11. A method of recording electrocardiographic data to provide the capability for the analysis of the presence of micropotentials comprising the steps of:

attaching a plurality of electrocardiographic (ECG) electrodes to a subject patient, each of said electrodes detecting a bioelectric signal of the human heart and generating, therefrom, an analog ECG signal;

converting each of said analog ECG signals into a digital representation of said analog ECG signal such that each of said digital representations represents a specific point in time relative to said analog ECG signal;

recording said bioelectric signals of the human heart on a plurality of data channels such that each of said bioelectric signals is separately stored on one of said plurality of data channels;

sampling and signal averaging of said digital representations for each of said analog ECG signals represented by said digital representations;

summating said averaged digital representations;

storing said summated signal averaged version of said digital representations on at least one of said channels.

12. The method disclosed in claim 11 wherein the step of recording of said bioelectric signals of the human heart consists of long term ambulatory recording of said analog ECG signals generated by said plurality of electrodes.

13. The method disclosed in claim 11 wherein the step of recording said bioelectric signals of the human heart consists of recording said digital representations derived from said converting step.

14. The method disclosed in claim 11 wherein the step of sampling and signal averaging further includes:

obtaining a correlation coefficient;

correlating each beat to said correlation coefficient; and

eliminating nonrepetitive noise and irregular beats based on results obtained from said correlating step.

15. The method of claim 11 wherein the step of recording further includes employing a storage device which is selected from the group consisting of (1) analog magnetic tape;

(2) digital audio tape (DAT);

(3) solid state recorder with limited memory;

(4) solid state recorder with extended memory;

(5) rotating magnetic media;

(6) rotating optical media;

(7) rotating magneto-optical media; and

(8) removable memory card media.

16. The method of claim 11 further including performing the step of sampling and signal averaging during a predetermined time period.

17. The method as disclosed by claim 11 wherein the step of storing further includes interrupting the recording of at least one of said plurality of data channels used to record said ECG signals and placing on said interrupted channel said summated signal averaged signals.

18. The method disclosed by claim 11 further comprising the step of playing back all said ECG data and all said summated signal averaged signals, at a speed many times that used in said recording step to record said ECG data and said summated signal averaged signals, to an ECG analysis system.

19. A system for detecting and analyzing electrocardiographic micropotentials of the human heart comprising:

a Holter recorder being electrically connected to a plurality of electrodes, said recorder having a plurality of data channels such that there is at least one data channel for each of said plurality of electrodes, said recorder being capable of sensing and recording the bio-electric signals or the human heart;

analysis means contained within said recorder, said analysis means being operative to create a digital signal average for each of the signals received from said electrodes by said recorder;

storage means to record said digital signal averages on said recorder.

20. The invention of claim 19 wherein said analysis means is capable for high resolutions digitization of signals received via said electrodes.

21. The invention of claim 19 wherein said signal average, produced by said analysis means, is a simultaneous digital average of a predetermined sample of signals received via said electrodes.

22. The invention of claim 19 wherein said storage means records said signal average by interrupting one of said channels used to record data for one of said electrodes and placing thereon, said digital signal average.

23. The invention of claim 19 wherein said storage means records said signal average on a separate channel from tracks used to record electrode data.

24. The invention of claim 23 wherein said separate track is a timing track used to store a timing signal that is operative in synchronizing ECG data received from said electrodes, said timing signal being modulated with said signal averaged beat data, thereby, storing said signal averaged beat data on said timing track.

25. The invention of claim 19 further comprising playback means to reproduce recorded digital signal averages.

26. The invention of claim 19 wherein said analysis means further includes means to correlate each beat to a previously defined correlation coefficient thus providing a basis of eliminating extraneous nonrepetitive noise and other irregular beats.

27. The invention of claim 19 wherein said storage means is selected from the group consisting of:

(1) analog magnetic tape;

(2) digital audio tape (DAT);

(3) solid state recorder with limited memory;

(4) solid state recorder with extended memory;

(5) rotating magnetic media;

(6) rotating optical media;

(7) rotating magneto-optical media; and

(8) removable memory card media.