Cardiac rhythm monitoring device

• US 20030023178A1
• Filed: 05/29/2002
• Published: 01/30/2003
• Est. Priority Date: 05/29/2001
• Status: Active Grant

• Current Assignee: Edward T. Bischoff, Gary D. Menszer
• Original Assignee: Edward T. Bischoff, Gary D. Menszer
• Inventors: Bischoff, Edward T., Menszer, Gary D.
• Granted Patent: US 7,187,965 B2
• Time in Patent Office: Days
• US Class Current: 600/515
• CPC Class Codes: A61B 5/02405 Determining heart rate variability
• CPC Class Codes: A61B 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
• CPC Class Codes: A61B 5/364 Detecting abnormal ECG interval, e.g. extrasystoles, ectopic heartbeats
• CPC Class Codes: A61B 5/4839 combined with drug delivery
• CPC Class Codes: A61B 5/681 Wristwatch-type devices

Abstract

The present invention is a cardiac rhythm-monitoring device, which allows patients to perform a preliminary screening for supraventricular arrhythmia. The device detects beat-to-beat heart rhythms (i.e. the R-R interval between individual heart beats) and performs a screening test to determine if there are indications of arrhythmia. The test looks for variance in the R-R interval that is outside of the normal range, either using a pre-constructed chart based upon general population studies to determine the normal range of variance or using normal distribution analysis of the patient'"'"'s own heart rhythm to determine the normal range of variance for determining irregular heartbeats, and if there are multiple irregularities within the sensed time frame, the patient is warned of potential supraventricular arrhythmia. By sensing both electrical impulses form the heart and mechanical responses to the heartbeat, the device may augment its analysis.

Claims

1. A device comprising:

a means for sensing beat-to-beat heartbeat intervals;

a means for storing beat-to-beat heartbeat interval data;

a means for analyzing beat-to-beat heartbeat interval data to determine if there are indications of possible arrhythmia.

2. A device as in claim 1 further comprising an output device and a power source.

3. A device as in claim 1 wherein said means for analyzing beat-to-beat heartbeat interval data further comprises a processing unit and an arrhythmia detection algorithm.

4. A device as in claim 2 wherein said means for analyzing beat-to-beat heartbeat interval data further comprises a processing unit and an arrhythmia detection algorithm, and wherein said means for storing beat-to-beat heartbeat interval data is an array.

5. A device as in claim 3 wherein said means for sensing beat-to-beat heartbeat intervals is non-invasive.

6. A device as in claim 5 wherein said means for sensing beat-to-beat heartbeat intervals further comprises two conductive electrodes.

7. A device as in claim 6 further comprising a second means for sensing beat-to-beat heartbeat intervals, wherein said second means for sensing beat-to-beat heartbeat intervals senses a patient'"'"'s mechanical heartbeat indications.

8. A device as in claim 4 wherein said means for sensing beat-to-beat heartbeat intervals further comprises two conductive electrodes.

9. A device as in claim 3 wherein said arrhythmia detection algorithm monitors for irregular variance in the R-R interval between heartbeats outside of the normal range of variance in the R-R interval between heartbeats, and wherein the normal range of variance is determined from general population studies.

10. A device as in claim 9 further comprising an output device, wherein said arrhythmia detection algorithm further counts the number of irregular variances in the R-R interval between heartbeats outside of the normal range and directs said processing unit to transmit a signal to said output device warning of a potential arrhythmia in the event that the number of irregular variances in the R-R interval between heartbeats outside of the normal range exceeds a pre-set criteria indicating likely arrhythmia.

11. A device as in claim 9 wherein the normal range of variance in the R-R interval between heartbeats is less than or equal to approximately 125 milliseconds, such that any variance in the R-R interval between heartbeats which is greater than approximately 125 milliseconds is an irregular variance in R-R interval between heartbeats outside of the normal range.

12. A device as in claim 11 wherein said processing unit executes said arrhythmia detection algorithm to monitor for irregular variance in the R-R interval between heartbeats outside of the normal range and counts the number of irregular variances in the R-R interval between heartbeats outside of the normal range.

13. A device as in claim 12 further comprising an output device, wherein said processing unit transmits a signal to said output device warning of a potential arrhythmia in the event that the number of irregular variances in the R-R interval between heartbeats outside of the normal range exceeds a pre-set criteria indicating likely arrhythmia.

14. A device as in claim 3 wherein said arrhythmia detection algorithm normalizes said sensed beat-to-beat heartbeat interval data and employs statistical normal distribution analysis to classify heartbeat intervals as indicative of instability.

15. A device as in claim 14 further comprising an output device, wherein said arrhythmia detection algorithm further counts the number of normalized heartbeat intervals indicating instability and directs said processing unit to transmit a signal to said output device warning of a potential arrhythmia in the event that the number of normalized heartbeat intervals indicating instability exceeds a pre-set criteria indicating likely arrhythmia.

16. A device as in claim 14 wherein a normalized beat-to-beat heartbeat interval indicates instability if it falls outside the range from approximately 0.95 to 1.05.

17. A device as in claim 14 wherein said arrhythmia detection algorithm indicates an unstable heart rhythm possibly indicative of arrhythmia if the number of normalized heartbeat intervals indicating instability exceeds the number of normalized heartbeat intervals indicating stability.

18. A device as in claim 17 wherein said sensed beat-to-beat heartbeat interval data is normalized by dividing each sensed beat-to-beat heartbeat interval by the succeeding sensed beat-to-beat heartbeat interval.

19. A device as in claim 17 wherein said sensed beat-to-beat heartbeat interval data is normalized by dividing each sensed beat-to-beat heartbeat interval by the average beat-to-beat heartbeat interval.

20. A device as in claim 17 further comprising an output device, wherein said processing unit executes said arrhythmia detection algorithm and transmits an output signal warning of possible arrhythmia to said output device in the event that said algorithm indicates an unstable heart rhythm.

21. A device as in claim 4 wherein said processing unit and said power source are located within said housing, wherein said output device is further comprised of a display located atop said housing, wherein said means for sensing beat-to-beat heartbeat intervals is further comprised of two conductive electrodes, and wherein one of said conductive electrodes is located on each side of said housing.

22. A device as in claim 4 further comprising one or more sensor housings, a data transmission means, and a data receiving means, and wherein said means for sensing beat-to-beat heartbeat intervals is further comprised of two conductive electrodes.

23. A device comprising:

a non-invasive sensor for detecting beat-to-beat heartbeat intervals;

a means for storing beat-to-beat heartbeat interval data;

an output device;

a power source;

a microprocessor; and

an arrhythmia detection algorithm.

24. A device as in claim 23 wherein said sensor detects beat-to-beat heartbeat intervals by sensing the electrical impulses generated by a patient'"'"'s heart.

25. A device as in claim 23 wherein said sensor detects beat-to-beat heartbeat intervals by sensing mechanical indications of a patient'"'"'s heart.

26. A device as in claim 24 wherein said sensor is further comprised of two conductive electrodes.

27. A device as in claim 26 wherein said arrhythmia detection algorithm monitors for irregular variance in the R-R interval between heartbeats outside of the normal range of variance in the R-R interval between heartbeats, and wherein the normal range of variance is determined from general population studies.

28. A device as in claim 27 wherein the normal range of variance in the R-R interval between heartbeats is less than or equal to approximately 125 milliseconds, such that any variance in the R-R interval between heartbeats which is greater than approximately 125 milliseconds is an irregular variance in R-R interval between heartbeats outside of the normal range.

29. A device as in claim 27 wherein said microprocessor executes said arrhythmia detection algorithm to monitor for irregular variance in the R-R interval between heartbeats outside of the normal range and counts the number of irregular variances in the R-R interval between heartbeats outside of the normal range.

30. A device as in claim 29 further comprising an output device, wherein said microprocessor transmits a signal to said output device warning of a potential arrhythmia in the event that the number of irregular variances in the R-R interval between heartbeats outside of the normal range exceeds a pre-set criteria indicating likely arrhythmia.

31. A device as in claim 26 wherein said arrhythmia detection algorithm normalizes said sensed beat-to-beat heartbeat interval data and employs statistical normal distribution analysis to classify heartbeats intervals as indicative of instability.

32. A device as in claim 31 wherein a normalized beat-to-beat heartbeat interval indicates instability if it falls outside the range from approximately 0.95 to 1.05.

33. A device as in claim 31 wherein said arrhythmia detection algorithm indicates an unstable heart rhythm possibly indicative of arrhythmia if the number of normalized heartbeat intervals indicating instability exceeds the number of normalized heartbeat intervals indicating stability.

34. A device as in claim 33 wherein said sensed beat-to-beat heartbeat interval data is normalized by dividing each sensed beat-to-beat heartbeat interval by the succeeding sensed beat-to-beat heartbeat interval.

35. A device as in claim 33 wherein said sensed beat-to-beat heartbeat interval data is normalized by dividing each sensed beat-to-beat heartbeat interval by the average beat-to-beat heartbeat interval.

36. A device as in claim 33 further comprising an output device, wherein said microprocessor executes said arrhythmia detection algorithm and transmits an output signal warning of possible arrhythmia to said output device in the event that said algorithm indicates an unstable heart rhythm.

37. A device as in claim 36 further comprising one or more secondary sensors, wherein said secondary sensors detect beat-to-beat heartbeat intervals by sensing the mechanical indications of a patient'"'"'s heart.

38. A device as in claim 37 wherein said secondary sensors are further comprised of one or more of a pulse oximeter and a peak blood flow pressure sensor.

39. A device as in claim 36 further comprising non-volatile memory, a digitizer, and a noise and bandwidth filter unit, and wherein said means for storing beat-to-beat heartbeat intervals is an array.

40. A method for detecting potential arrhythmia comprising the steps of:

sensing beat-to-beat heart rhythm;

calculating the average R-R interval between heartbeats;

calculating the variance in the R-R interval for each measured R-R interval by taking the absolute value of the difference between the measured R-R interval and the average R-R interval;

monitoring the variance in the R-R interval to determine if it is outside of the normal range;

counting the number of times that the variance in the R-R interval is outside of the normal range; and

outputting result if the counted number of irregular variances in the R-R interval between heartbeats outside of the normal range is indicative of a sustained pattern of irregularity indicating a possibility of arrhythmia.

41. A method for detecting arrhythmia as in claim 40 further comprising the steps of storing the sensed R-R intervals and storing the number of times that the variance in the R-R interval is outside of the normal range.

42. A method for detecting arrhythmia as in claim 40 wherein the normal range of variance in the R-R interval between heartbeats is determined from a study of the general population of healthy adults.

43. A method for detecting arrhythmia as in claim 41 wherein the normal range of variance in the R-R interval between heartbeats is less than or equal to approximately 125 milliseconds, such that any variance in the R-R interval between heartbeats which is greater than approximately 125 milliseconds is an irregular variance in the R-R interval between heartbeats outside of the normal range.

44. A method for detecting arrhythmia as in claim 42 wherein a warning is output to notify the user of a potential arrhythmia if the variance in the R-R interval is outside of the normal range more than twice within a one minute period.

45. A method for detecting arrhythmia as in claim 40 further comprising sensing the R-R interval between heartbeats using two different sensors, using the second sensed R-R interval data as a check of the accuracy of the first sensed R-R interval data for redundant arrhythmia verification.

46. A method for detecting arrhythmia as in claim 45 wherein said first sensor detects the electrical impulses generated by the heart and said second sensor detects the mechanical indications of the heartbeat.

47. A method for detecting potential arrhythmia comprising the steps of:

sensing a patient'"'"'s beat-to-beat heartbeat intervals;

storing said beat-to-beat heartbeat interval data;

normalizing said beat-to-beat heartbeat interval data;

analyzing each piece of normalized beat-to-beat heartbeat data in comparison to a stability criteria to determine if said data indicates stability or instability of the patient'"'"'s heart rhythm;

tracking the number of normalized beat-to-beat heartbeat data indicating stability and the number of normalized beat-to-beat heartbeat data indicating instability;

outputting a warning to the patient if the number of normalized beat-to-beat heartbeat data indicating instability exceeds the pre-set criteria.

48. A method for detecting arrhythmia as in claim 47 wherein said stability criteria for classifying a normalized beat-to-beat heartbeat interval as stable is approximately between 0.95 and 1.05, and wherein said pre-set criteria for outputting a warning to the patient is when the number of normalized beat-to-beat heartbeat intervals indicating instability exceeds the number of normalized beat-to-beat heartbeat intervals indicating stability.

49. A method for detecting arrhythmia as in claim 47 wherein at least 8 beat-to-beat heartbeat intervals are sensed and analyzed.

50. A method for detecting arrhythmia as in claim 47 wherein beat-to-beat heartbeat intervals are sensed and analyzed in sets of 32.

51. A method for detecting arrhythmia as in claim 47 wherein the method for normalizing the beat-to-beat heartbeat interval data is by dividing each sensed beat-to-beat heartbeat interval by the succeeding sensed beat-to-beat heartbeat interval.

52. A method for detecting arrhythmia as in claim 47 further comprising the step of calculating the average heartbeat interval for the sensed set of beat-to-beat heartbeat intervals, and wherein the method for normalizing the beat-to-beat heartbeat interval data is by dividing each sensed beat-to-beat heartbeat interval by the average heartbeat interval.

53. A method for detecting arrhythmia as in claim 47 further comprising the steps of:

ensuring that the patient'"'"'s heartbeat is within the normal resting range;

performing noise and bandwidth filtering on the sensed beat-to-beat heartbeat interval data; and

digitizing the sensed beat-to-beat heartbeat interval data signal.

54. A method for detecting potential arrhythmia using a tri-phase analysis comprising the steps of:

sensing a patient'"'"'s beat-to-beat heartbeat intervals;

storing said beat-to-beat heartbeat interval data;

analyzing said beat-to-beat heartbeat interval data in discrete sets;

calculating the average heartbeat interval for each set of beat-to-beat heartbeat intervals;

phase-one normalizing each piece of beat-to-beat heartbeat interval data within a set by dividing each sensed beat-to-beat heartbeat interval by the succeeding sensed beat-to-beat heartbeat interval;

analyzing each piece of phase-one normalized beat-to-beat heartbeat data in comparison to a stability criteria to determine if said data indicates stability or instability of the patient'"'"'s heart rhythm;

tracking the number of phase-one normalized beat-to-beat heartbeat data indicating stability and the number of phase-one normalized beat-to-beat heartbeat data indicating instability;

designating a phase-one result of “

Stable”

if the number of phase-one normalized beat-to-beat heartbeat interval data indicating stability exceeds a pre-set determination criteria, while designating a phase-one result of “

Unstable”

if the number of phase-one normalized beat-to-beat heartbeat interval data indicating instability exceeds a pre-set determination criteria;

phase-two normalizing each piece of beat-to-beat heartbeat interval data within a set by dividing each sensed beat-to-beat heartbeat interval by the average heartbeat interval for said set;

analyzing each piece of phase-two normalized beat-to-beat heartbeat data in comparison to a stability criteria to determine if said data indicates stability or instability of the patient'"'"'s heart rhythm;

tracking the number of phase-two normalized beat-to-beat heartbeat data indicating stability and the number of phase-two normalized beat-to-beat heartbeat data indicating instability;

designating a phase-two result of “

Stable”

if the number of phase-two normalized beat-to-beat heartbeat interval data indicating stability exceeds a pre-set determination criteria, while designating a phase-two result of “

Unstable”

if the number of phase-two normalized beat-to-beat heartbeat interval data indicating instability exceeds a pre-set determination criteria;

comparing said phase-one result and said phase-two result;

setting said overall result as “

Stable”

if both said phase-one result and said phase-two result are “

Stable,”

while setting said overall result as “

Unstable”

if both said phase-one result and said phase-two result are “

Unstable;

” and

outputting a warning if said overall result is “

Unstable.”

55. A method as in claim 54 further comprising the step of iteratively performing said phase-one and said phase-two analysis on additional successive sets of beat-to-beat heartbeat interval data until both said phase-one result and said phase-two result match.

56. A method as in claim 55 further comprising the step of outputting a warning regarding potential arrhythmia if said phase-one result and said phase-two result have not matched after three iterations.

57. A method as in claim 55 wherein the pre-set determination criteria is arranged so that a phase-one result of “

Stable”

is designated if the number of phase-one normalized beat-to-beat heartbeat interval data indicating stability exceeds the number of phase-one normalized beat-to-beat heartbeat interval data indicating instability, a phase-one result of “

Unstable”

is designated if the number of phase-one normalized beat-to-beat heartbeat interval data indicating instability exceeds the number of phase-one normalized beat-to-beat heartbeat interval data indicating stability, a phase-two result of “

Stable”

is designated if the number of phase-two normalized beat-to-beat heartbeat interval data indicating stability exceeds the number of phase-two normalized beat-to-beat heartbeat interval data indicating instability, and a phase-two result of “

Unstable”

is designated if the number of phase-two normalized beat-to-beat heartbeat interval data indicating instability exceeds the number of phase-two normalized beat-to-beat heartbeat interval data indicating stability.

58. A method as in claim 55 wherein said stability criteria for classifying a normalized beat-to-beat heartbeat interval as stable is approximately between 0.95 and 1.05.

59. A method as in claim 56 wherein said stability criteria for classifying a normalized beat-to-beat heartbeat interval as stable is approximately between 0.95 and 1.05.

60. A method as in claim 55 further comprising the steps of

ensuring that the patient'"'"'s heartbeat is within the normal resting range;

performing noise and bandwidth filtering on the sensed beat-to-beat heartbeat interval data; and

digitizing the sensed beat-to-beat heartbeat interval data signal.

62. A method as in claim 60 wherein the arrhythmia detection analysis utilizes statistical normalization techniques and normal distribution analysis to determine if a particular beat-to-beat heartbeat interval variance falls outside of the normal range.

63. A method as in claim 60 wherein the arrhythmia detection analysis calculates the variance for each sensed beat-to-beat heartbeat interval based on the difference with the average heartbeat interval, and utilizes the results from general population studies to determine the normal range of variance.

61. A method for detecting potential arrhythmia comprising the steps of:

sensing beat-to-beat heartbeat intervals;

storing beat-to-beat heartbeat interval data;

analyzing beat-to-beat heartbeat interval data to detect signs of potential arrhythmia by noting instances when the variance for individual sensed beat-to-beat heartbeat interval data falls outside of the normal range; and

outputting a warning when said number of instances outside of the normal range indicates a pattern of irregularity.