MORPHOLOGY-BASED DISCRIMINATION ALGORITHM BASED ON RELATIVE AMPLITUDE DIFFERENCES AND CORRELATION OF IMPRINTS OF ENERGY DISTRIBUTION

• US 20130030481A1
• Filed: 07/30/2012
• Published: 01/31/2013
• Est. Priority Date: 07/31/2011
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Gillberg, Jeffrey M., Ghosh, Subham
• Granted Patent: US 8,750,994 B2
• Time in Patent Office: Days
• US Class Current: 607/14
• CPC Class Codes: A61B 5/316 Modalities, i.e. specific diagnostic methods
• CPC Class Codes: A61B 5/361 Detecting fibrillation
• CPC Class Codes: A61B 5/363 Detecting tachycardia or bradycardia
• CPC Class Codes: A61B 5/686 Permanently implanted devices, e.g. pacemakers, other stimulators, biochips A61B5/6861 takes precedence
• CPC Class Codes: A61N 1/3621 for treating or preventing abnormally high heart rate
• CPC Class Codes: A61N 1/3956 Implantable devices for applying electric shocks to the heart, e.g. for cardioversion
• CPC Class Codes: G06F 2218/16 by matching signal segments

Abstract

Techniques for morphologic discrimination between beats of a tachyarrhythmia episode are described for selecting delivery of appropriate therapy. An exemplary method comprises nonordered binning of digitized amplitude values of signals associated with cardiac depolarizations. Monomorphic VT is discriminated from polymorphic VT without signal alignment. One exemplary method involves sensing electrical signals associated with depolarizations of a patient'"'"'s heart during a tachyarrhythmia episode. The sensed electrical signals are converted to digital values and stored. The stored digital values are normalized and binned. At most, 5 pairs of beats or depolarizations are compared for morphologic similarity by determining the similarity between the binned values associated with each pair. The result of the comparison is used to select and deliver therapy to the patient.

Claims

1. A method of treating heart rhythms comprising:

sensing electrical signals associated with depolarizations of a patient'"'"'s heart;

converting the sensed electrical signals to digital values and storing the digital values;

normalizing the stored digital values associated with at least a pair of depolarizations of the patient'"'"'s heart;

binning the normalized digital values associated with the depolarizations;

comparing the binned values associated with one depolarization to the binned values associated with another depolarization in the pair of depolarizations; and

using a result of the comparison to select and deliver a therapy.

2. The method of claim 1 wherein the selected therapy is directed to treating heart rhythms related to one of monomorphic ventricular tachycardia (VT), and polymorphic VT.

3. The method of claim 2 further comprising:

determining the selected therapy without shifting and aligning the normalized digital values associated with one of the depolarizations to the normalized digital values associated with another depolarization.

4. The method of claim 2 wherein the binned values are digitized samples of the signal associated with each depolarization.

5. The method of claim 1 further comprising:

comparing peak-to-peak amplitudes of one depolarization and another depolarization; and

determining whether the peak-to-peak amplitudes of one depolarization and another depolarization in each pair have a relative difference of less than or equal to 20%.

6. The method of 5 further comprising:

determining similarity exists between one depolarization and another depolarization of the pair of depolarizations responsive to determining if their peak-to-peak amplitudes have a relative difference of less than 20%.

7. The method of 1 further comprising:

determining that a difference exists between one depolarization and another depolarization of the pair of depolarizations responsive to determining that the peak-to-peak amplitudes of the first and second depolarizations in the pair have a relative difference exceeding 20%.

8. The method of 6 further comprising:

determining whether the peak-to-peak amplitudes of the one depolarization and another depolarization of the pair of depolarizations have a relative difference of less than or equal to 20%, and

determining a correlation coefficient between an energy imprint for one depolarization and an energy imprint for another depolarization of the pair of depolarizations is less than or equal to 65%.

10. The method of claim 8 further comprising:

defining a first beat pair comprising the Nth and (N-2)th depolarizations;

defining a second beat pair comprising (N-2)th and (N-4) depolarizations ;

defining a third beat pair comprising (N-4)th and (N-6)th depolarizations;

defining a fourth beat pair comprising (N-6)th and (N-8)th depolarizations;

defining a fifth beat pair comprising (N-8)th and (N-10)th depolarizations;

wherein the first through fifth beat pairs relate to an episode, N>

10 and the Nth beat is the detection beat of the episode,

determining whether three or more beat pairs have a relative difference in peak-to-peak amplitudes less than or equal to 20% and a correlation coefficient between their respective energy imprints are greater than 65%.

11. The method of claim 10 wherein solely five or less beat-pair comparisons are performed to reliably select the therapy to be delivered.

12. The method of claim 10 further comprising:

detecting monomorphic VT if three or more beat pairs have a relative difference in peak-to-peak amplitudes less than or equal to 20% and a correlation coefficient between their respective energy imprints greater than 65%.

13. The method of claim 10 further comprising:

detecting polymorphic VT/VF if more than three of five beat pairs have relative difference in peak-to-peak amplitudes greater than 20% or correlation coefficient between their respective energy imprints less than or equal to 65%.

9. The method of 6 further comprising:

determining the energy imprint of one depolarization and the energy imprint of another depolarization in the pair of depolarizations;

comparing the energy imprint of the one depolarization to the energy imprint of another depolarization in the pair; and

determining whether the correlation coefficient exceeds 65% between the energy imprint of the one depolarization to the energy imprint of the other depolarization in the pair.

14. A method of treating heart rhythms, comprising:

sensing electrical signals associated with depolarizations of a patient'"'"'s heart;

converting the sensed electrical signals to digital values, and storing the digital values associated with each depolarization;

determining whether to deliver therapy to the patient;

(a) comparing a first and a second depolarization of a pair of depolarizations,

(b) determining whether the first and second depolarizations in the pair depolarizations exhibit a relative difference in peak-to-peak amplitudes of less than or equal to 20%;

(c) normalizing and binning the normalized digitized values associated with each depolarization into pre-defined bins;

(d) determining whether the correlation coefficient between the respective binned values associated with each pair of depolarization is greater than 65%;

(e) repeating operations (a) through (d) for three or more pairs of depolarizations of an episode; and

using a result of the comparisons above, selecting a therapy and delivering it to the patient.

15. The method of claim 14 wherein the selected therapy is directed to treating heart rhythms including one of supraventricular tachycardia, ventricular tachycardia (VT), monomorphic VT, and polymorphic VT.

16. The method of 15 further comprising:

determining the first and second depolarizations in a pair are similar responsive to determining if their peak-peak amplitudes have a relative difference of less than or equal to 20%, and the correlation coefficient between their respective energy-imprints is greater than 65%.

17. A method of treating heart rhythms, comprising:

sensing electrical signals associated with depolarizations of a patient'"'"'s heart;

converting the sensed electrical signals to digital values, and storing the digital values associated with each depolarization;

normalizing and binning the digitized values associated with each depolarization into pre-defined bins;

comparing peak-to-peak amplitudes and binned values between pairs of depolarizations;

determining whether the two depolarizations in a pair have a relative difference in peak-to-peak amplitudes of less than or equal to 20%;

determining if the correlation coefficient between the respective binned values in a pair is greater than 65%; and

using a result of the comparisons above, selecting a therapy and delivering it to the patient.

18. A method of treating heart rhythms, comprising:

normalizing a signal associated with one beat of a tachyarrhythmia episode;

computing an imprint of energy distribution using the normalized signal; and

comparing the imprint of energy distribution to that of a normalized signal derived from another beat of the same episode or a normalized signal associated with depolarization of a known type.

19. A method of treating heart rhythms comprising:

sensing electrical signals associated with depolarizations of a patient'"'"'s heart;

converting the sensed electrical signals to digital values and storing the digital values;

normalizing the stored digital values associated with at least first and second depolarizations of the patient'"'"'s heart;

binning the normalized digital values associated with the first and second depolarizations into pre-defined bins;

comparing peak-to-peak amplitude of the first depolarization to peak-to-peak amplitude of the second depolarization;

comparing the binned values associated with the first depolarization to the binned values associated with the second depolarization;

using a result of the comparisons to select and deliver a therapy,

wherein the selected therapy is directed to treating one of monomorphic VT and polymorphic VT.

20. An article comprising a computer readable medium having instructions stored thereon, which when executed, causes:

sensing electrical signals associated with depolarizations of a patient'"'"'s heart;

converting the sensed electrical signals to digital values and storing the digital values;

normalizing the stored digital values associated with at least a pair of depolarizations of the patient'"'"'s heart;

binning the normalized digital values associated with each depolarization into pre-defined bins;

comparing the peak-to-peak amplitude of the first depolarization to peak-to-peak amplitude of the second depolarization;

comparing the binned values associated with one depolarization to the binned values associated with another depolarization in the pair of depolarizations; and

using a result of the comparisons to select and deliver a therapy.

21. The article of claim 20 wherein the selected therapy is directed to treating one of monomorphic VT and polymorphic VT.

22. The article of claim 21 further comprising:

determining the selected therapy using a result of morphologic comparison between pairs of depolarizations without shifting and aligning the normalized digital values associated with one depolarizations to those associated with another depolarization in each pair.

23. The article of claim 21 wherein the binned values are normalized digitized samples of the signal associated with each depolarization.

24. The article of claim 20 further comprising:

comparing peak-to-peak amplitudes between pairs of depolarizations; and

determining whether the peak-to-peak amplitudes of one depolarization and another depolarization in a pair have a relative difference of less than or equal to 20%.

25. A system for detecting and treating a cardiac condition comprising:

means for sensing electrical signals associated with depolarizations of a patient'"'"'s heart;

means for converting the sensed electrical signals to digital values and storing the digital values;

means for normalizing the stored digital values associated with at least a pair of depolarizations of the patient'"'"'s heart;

means for comparing the peak-to-peak amplitude of one depolarization to peak-to-peak amplitude of another depolarization in each pair

means for binning the normalized digital values associated with the depolarizations into pre-defined bins;

means for comparing the binned values associated with one depolarization to the binned values associated with another depolarization in the pair of depolarizations; and

means for using a result of the comparison of the peak-to-peak amplitudes and binned values associated with solely five or less number of depolarization-pairs to select and deliver a therapy.

26. The system of claim 25 wherein the selected therapy is directed to treating heart rhythms related to one of monomorphic VT, and polymorphic VT.

27. A method of treating heart rhythms comprising:

sensing electrical signals associated with depolarizations of a patient'"'"'s heart;

converting the sensed electrical signals to digital values and storing the digital values;

normalizing the stored digital values associated with at least a pair of depolarizations of the patient'"'"'s heart; and

binning the normalized digital values associated with the depolarizations into pre-defined bins.

28. The method of claim 27 wherein distribution of the normalized binned values of each depolarization is an imprint of energy distribution.

29. The method of claim 28 further comprising comparing the energy imprint associated with one depolarization to an energy imprint associated with another depolarization in the pair of depolarizations;

and

using a result of the comparison to select and deliver a therapy.

30. The method of claim 27 wherein the selected therapy is directed to treating heart rhythms one of supraventricular tachycardia, ventricular tachycardia (VT), monomorphic VT, and polymorphic VT.

31. The method of claim 28 further comprising:

determining the selected therapy using a result of morphologic comparison between pairs of depolarizations without shifting and aligning the normalized digital values associated with one of the depolarizations to those associated with another depolarization in each pair.

32. The method of claim 28 wherein the binned values are the normalized digitized samples of the signal associated with each depolarization.

33. The method of claim 27 further comprising:

comparing peak-to-peak amplitudes between pairs of depolarizations; and

determining whether the peak-to-peak amplitudes of one depolarization and another depolarization in a pair have a relative difference of less than or equal to 20%.

34. The method of 33 further comprising:

determining the one depolarization and the another depolarization in the pair are similar responsive to determining if their peak-peak amplitudes have a relative difference of less than or equal to 20%, and

determining a correlation coefficient between their respective energy-imprints is greater than 65%.

35. The method of 34 further comprising:

determining that the two depolarizations in a pair are different responsive to determining that the peak-to-peak amplitudes of the first and second depolarizations in the pair have a relative difference exceeding 20%, or if the peak-to-peak amplitudes of the first and second depolarizations have a relative difference of less than or equal to 20%, and the correlation coefficient between their respective energy-imprints is less than or equal to 65%.

36. The method of 35 further comprising:

determining imprints of energy distribution of the two depolarizations in a pair;

comparing the imprint energy distribution of one depolarization to the imprint of energy distribution of the other depolarization in the pair; and

determining whether the correlation coefficient between the respective energy imprints exceeds 65%.

37. The method of claim 36 further comprising:

defining a first depolarization pair comprising the Nth and (N-2)th depolarizations

defining a second depolarization pair comprising (N-2)th and (N-4) depolarizations

defining a third depolarization pair comprising (N-4)th and (N-6)th depolarizations

defining a fourth depolarization pair comprising (N-6)th and (N-8)th depolarizations

defining a fifth depolarization pair comprising (N-8)th and (N-10)th depolarizations,

wherein the first through fifth depolarization pairs relate to an episode, N>

10 and the Nth depolarization is the detection depolarization of the episode;

determining whether three or more depolarization pairs have a relative difference in peak-to-peak amplitudes less than or equal to 20%; and

determining a correlation coefficient between their respective energy imprints greater than 65%.

38. The method of claim 37 wherein solely five or less depolarization-pair comparisons are performed to reliably select the therapy to be delivered.

39. The method of claim 38 further comprising:

detecting monomorphic VT if three or more depolarization pairs have a relative difference in peak-to-peak amplitudes less than or equal to 20%; and

determining a correlation coefficient between their respective energy imprints greater than 65%.

40. The method of claim 39 further comprising:

detecting polymorphic VT/VF if more than three of five depolarization pairs have relative difference in peak-to-peak amplitudes greater than 20% or correlation coefficient between their respective energy imprints less than or equal to 65%.