METHOD AND APPARATUS FOR DETECTING CARDIAC ARRHYTHMIAS

• US 3,828,768 A
• Filed: 07/13/1972
• Issued: 08/13/1974
• Est. Priority Date: 07/13/1972
• Status: Expired due to Term

• Current Assignee: David W. Douglas
• Original Assignee: David W. Douglas
• Inventors: Douglas, David W.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US05/271,373
• Time in Patent Office: 761 Days
• Field of Search: 128/2.6A,2.6RF,2.5P,2.5R,2.5T
• US Class Current: 600/515
• CPC Class Codes: A61B 5/364 Detecting abnormal ECG interval, e.g. extrasystoles, ectopic heartbeats
• CPC Class Codes: A61B 5/7242 using integration

Abstract

A continuous electrical wave representing the electrical action of a patient'"'"''"'"'s heart is produced (the ECG wave). Frequency components of the ECG wave that lie predominantly below the frequency range of the normal QRS complex are sensed, these frequency components being typically in the range of about two Hertz to about eight Hertz. These frequency components are integrated upon the occurrence of a QRS complex, and the magnitude of the result is then compared to a reference standard. If the magnitude of the integral exceeds the reference standard an output signal indicative of a cardiac arrhythmia is then produced.

Claims

1. The method of analyzing a continuous electrical wave representing the electrical action of a patient'"'"''"'"'s heart in order to detect cardiac arrhythmias, comprising the steps of:

applying the wave concurrently to a relativeLy high frequency band pass filter which is responsive to frequencies in the range from 10 to 30 Hertz, and to a relatively low frequency band pass filter which is responsive to frequencies in the range below 10 Hertz;

producing a timing signal in response to an output from said high frequency filter;

integrating the output of said low frequency filter throughout the duration of said timing signal;

comparing the integral to a reference standard; and

whenever the integral exceed the reference standard, producing an output signal indicating that a cardiac arrhythmia has occurred.

2. The method of claim 1 wherein said high frequency filter is selected to be predominantly responsive to frequencies in the range from 10 to 18 Hertz.

3. The method of claim 1 wherein said low frequency filter is selected to be predominatly responsive to frequencies in the range from 2 to 8 Hertz.

4. The method of claim 1 wherein said step of producing a timing signal includes continuing said timing signal for about 50 milliseconds after discontinuance of an output from said high frequency filter.

5. The method of claim 1 which additionally includes the prior step of first selecting a particular value of said reference standard which is applicable to the particular patient whose cardiac action is to be monitored.

6. The method of claim 1 wherein said step of producing a timing signal includes continuing said timing signal so long as an output in being produced by said high frequency filter and for at least several milliseconds thereafter.

7. The method of analyzing the ECG wave of a patient comprising the steps of:

filtering from the wave relatively high frequency components in the range from 10 to 18 Hertz;

filtering from the wave relatively low frequency components in the range from 2 to 8 Hertz;

producing a timing signal in response to the occurrence of said high frequency components;

integrating said low frequency components throughout the duration of said timing signal; and

whenever the value of the integral exceeds a predetermined reference standard, producing an output signal indicating that a cardiac arrhythmia has occurred.

8. The method of claim 7 which includes the further step of maintaining said timing signal so long as said high frequency components exist and for about 50 milliseconds thereafter.

9. The method of claim 7 wherein said reference standard is previously selected for the particular patient.

10. The method of analyzing the ECG wave of a patient, comprising the steps of:

filtering from the wave a band of high frequencies selected from the range of about 10 to about 30 Hertz;

concurrently filtering from the wave a band of low frequencies selected from the range below about 10 Hertz;

producing a timing signal in response to the occurrence of said high frequencies; and

first rectifying and then integrating said low frequencies throughout each occurrence of said timing signal in order to determine whether a cardiac arrhythmia has occurred.

11. The method claimed in claim 10 wherein the resulting integral is compared to a reference standard.

12. The method claimed in claim 11 wherein said reference standard is previously established to reflect the normal heart action of the patient, and an output signal indicating a cardiac arrhythmia is produced whenever said resulting integral exceeds said standard.

13. The method claimed in claim 12 wherein said reference standard is selected to be significantly greater than the minimum integral of said low frequencies which is produced during normal heart action of the patient.

14. The method of analyzing the ECG wave of a patient, comprising the steps of:

filtering from the wave a band of relatively low frequency components selected from the range below about 10 Hertz;

integrating said low frequency cOmponents in response to the occurrence of each one of a succession of QRS complexes;

comparing each one of the resulting integrals with a reference standard; and

whenever one of said resulting integrals exceeds said reference standard, producing an output signal indicating that a cardiac arrhythmia has occurred.

15. The method claimed in claim 14 which includes the further steps of:

filtering from the wave a band of relatively high frequency components selected from the range of about 10 to about 18 Hertz; and

generating a timing signal throughout the existence of said frequency components and for at least several milliseconds thereafter; and

wherein said low frequency components are integrated throughout the duration of said timing signal.

16. The method claimed in claim 15 which includes the additional step of maintaining said timing signal for about fifty milliseconds after said high frequency components cease to exist.

17. The method claimed in claim 14 wherein said reference standard is established by:

integrating said low frequency components throughout the duration of each one of sample sets of QRS complexes of that patient to obtain a corresponding sample set of integrals; and

selecting said reference standard to be significantly greater than the value of the largest integral of said sample set.

18. The method claimed in claim 17 which includes the additional step of visually displaying said sample set of QRS complexes before selecting said reference standard.

19. Apparatus for detecting cardiac arrhythmias comprising, in combination:

input means for producing the ECG wave;

a filter coupled to said input means for filtering from the wave a band of frequency components selected from the range below about 10 Hertz;

a full-wave rectifier coupled to said filter for rectifying said band of frequency components;

an integrator coupled to said rectifier and operable for integrating said band of frequency components;

timing means coupled to said integrator for enabling the same upon the occurrence of each one of a succession of QRS complexes;

means for providing a reference standard;

comparison means coupled to said integrator and to said reference standard means for comparing each one of the resulting integrals with the reference standard; and

output means responsive to said comparison means whenever one of said resulting integrals exceeds said reference standard for producing an output signal indicating that a cardiac arrhythmia has occurred.

20. Apparatus as claimed in claim 19 wherein said timing means includes:

an additional filter coupled to said input means for filtering from the wave a band of relatively high frequency components selected from the range of about 10 to about 30 Hertz; and

means coupled to said additional filter for generating a timing signal in response to the existence of said high frequency components;

the output of said generating means being coupled to said integrator for selectively turning said integrator on and off in response to said timing signal.

21. Apparatus as claimed in claim 20 wherein said generating means is adapted to generate said timing signal throughout the existence of said high frequency components and for at least several milliseconds thereafter.