Medical device

• US 20050107836A1
• Filed: 02/27/2003
• Published: 05/19/2005
• Est. Priority Date: 02/28/2002
• Status: Active Grant

• Current Assignee: St. Jude Medical AB (Abbott Laboratories Incorporated)
• Original Assignee: St. Jude Medical AB (Abbott Laboratories Incorporated)
• Inventors: Noren, Kjell
• Granted Patent: US 7,283,865 B2
• Time in Patent Office: Days
• US Class Current: 607/9
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/361 Detecting fibrillation
• CPC Class Codes: A61B 5/363 Detecting tachycardia or bradycardia
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: A61N 1/3622 comprising two or more electrodes co-operating with different heart regions

Abstract

In a device and a method for determining a cardiac condition from a detected cardiac signal, an input signal is formed from the detected cardiac signal and supplied to an analysis unit. The analysis unit forms an analysis signal from the input signal, having a real part substantially corresponding to the input signal and an imaginary part that is a predetermined transformation of the input signal. A calculation unit operates on the analysis signal to calculated at least two heart-related parameters therefrom. The heart-related parameters are supplied to a processing unit that combines the heart-related parameters in a predetermined manner for identifying a cardiac condition.

Claims

1-30. -30. (canceled)

31. An implantable device for determining a cardiac condition comprising:

a detector adapted to detect a heart-related signal and for forming an input signal therefrom;

an analysis unit connected to said detector for receiving said input signal therefrom, for producing an analysis signal from said input signal having a real part substantially corresponding to said input signal and an imaginary part formed as a predetermined transformation of said input signal;

a calculation unit connected to said analysis unit and receiving said analysis signal therefrom, said calculation unit calculating at least two heart-related parameters from said analysis signal; and

a processing unit connected to said calculation unit and supplied with said heart-related parameters therefrom, said processing unit combining said heart-related parameters in a predetermined manner for identifying a cardiac condition.

32. A device as claimed in claim 31 wherein said analysis unit transform said input signal uses the Hilbert transform to form said imaginary part of said analysis signal.

33. A device as claimed in claim 31 wherein said analysis unit transforms said input signal using an approximate Hilbert transform to form said imaginary part of said analysis signal.

34. A device as claimed in claim 31 wherein said detector is adapted to obtain a signal indicative of right ventricular pressure as said heart-related signal.

35. A device as claimed in claim 31 wherein said detector is adapted to detect an intracardiac electrogram from the right ventricle as said heart-related signal.

36. A device as claimed in claim 31 wherein said calculation unit calculates an instantaneous amplitude, a frequency and a phase of said analysis signal as said at least two heart-related parameters.

37. A device as claimed in claim 31 wherein said processing unit combines said heart-related parameters by forming a quotient of two of said heart-related parameters.

38. A device as claimed in claim 37 wherein said calculation unit determines a frequency and an amplitude of said analysis signal as said at least two heart-related parameters, and wherein said processing unit forms said quotient between said frequency and said amplitude.

39. A device as claimed in claim 31 wherein said processing unit combines said at least two heart-related parameters by forming a product of at least two of said at least two heart-related parameters.

40. A device as claimed in claim 39 wherein said calculation unit determines a frequency and an amplitude of said analysis signal as said at least two heart-related parameters, and wherein said processing unit forms said product between said frequency and said amplitude.

41. A device as claimed in claim 31 wherein said processing unit combines said at least two heart-related parameters by plotting two of said at least two heart-related parameters in a diagram having a threshold line dividing said diagram into respective detection areas.

42. A device as claimed in claim 41 wherein said calculating unit calculates an amplitude and a frequency as said two of said at least two heart-related parameters, and wherein said processing unit plots said amplitude and said frequency along respective axes of said diagram.

43. A device as claimed in claim 31 wherein said analysis unit comprises at least one finite impulse response filter acting on said input signal.

44. A device as claimed in claim 31 wherein said analysis unit comprises at least one infinite impulse response filter acting on said input signal.

45. A device as claimed in claim 31 wherein said calculation unit calculates an absolute value, representing an instantaneous amplitude, of said analysis signal as one of said at least two heart-related parameters.

46. A device as claimed in claim 31 wherein said calculation unit calculates an instantaneous frequency of said analysis signal as one of said at least two heart-related parameters.

47. A device as claimed in claim 41 wherein said processing unit detects a fibrillation, selected from the group consisting of atrial fibrillation and ventricular fibrillation, from said combination of heart-related parameters, as said cardiac condition.

48. An implantable cardiac therapy device comprising:

a cardiac condition determining device comprising a detector adapted to detect a heart-related signal and for forming an input signal therefrom, an analysis unit connected to said detector for receiving said input signal therefrom, for producing an analysis signal from said input signal having a real part substantially corresponding to said input signal and an imaginary part formed as a predetermined transformation of said input signal, a calculation unit connected to said analysis unit and receiving said analysis signal therefrom, said calculation unit calculating at least two heart-related parameters from said analysis signal, a processing unit connected to said calculation unit and supplied with said heart-related parameters therefrom, said processing unit combining said heart-related parameters in a predetermined manner for identifying a cardiac condition; and

a therapy administering unit connected to said cardiac condition determining device and adapted to deliver a selected cardiac therapy dependent on said cardiac condition.

49. A method for determining a cardiac condition comprising the steps of:

detecting a heart-related signal in vivo and for forming an input signal therefrom;

electronically producing an analysis signal from said input signal having a real part substantially corresponding to said input signal and an imaginary part formed as a predetermined transformation of said input signal;

electronically calculating at least two heart-related parameters from said analysis signal; and

electronically combining said heart-related parameters in a predetermined manner for identifying a cardiac condition.

50. A method as claimed in claim 49 comprising transforming said input signal using the Hilbert transform to form said imaginary part of said analysis signal.

51. A method as claimed in claim 49 comprising transforming said input signal using an approximate Hilbert transform to form said imaginary part of said analysis signal.

52. A method as claimed in claim 49 comprising obtaining a signal indicative of right ventricular pressure as said heart-related signal.

53. A method as claimed in claim 49 comprising detecting an intracardiac electrogram from the right ventricle as said heart-related signal.

54. A method as claimed in claim 49 comprising electronically calculating an instantaneous amplitude, a frequency and a phase of said analysis signal as said at least two heart-related parameters.

55. A method as claimed in claim 49 comprising electronically combining said heart-related parameters by forming a quotient of two of said heart-related parameters.

56. A method as claimed in claim 55 comprising electronically determining a frequency and an amplitude of said analysis signal as said at least two heart-related parameters, and forming said quotient between said frequency and said amplitude.

57. A method as claimed in claim 49 comprising electronically combining said at least two heart-related parameters by forming a product of at least two of said at least two heart-related parameters.

58. A method as claimed in claim 57 comprising electronically determining a frequency and an amplitude of said analysis signal as said at least two heart-related parameters, and forming said product between said frequency and said amplitude.

59. A method as claimed in claim 49 comprising electronically combining said at least two heart-related parameters by plotting two of said at least two heart-related parameters in an electronic diagram having a threshold line dividing said electronic diagram into respective detection areas.

60. A method as claimed in claim 59 comprising electronically calculating an amplitude and a frequency as said two of said at least two heart-related parameters, and plotting said amplitude and said frequency along respective axes of said electronic diagram.