Implantable drug delivery system responsive to intra-cardiac pressure

• US 20030199813A1
• Filed: 04/22/2002
• Published: 10/23/2003
• Est. Priority Date: 04/22/2002
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Struble, Chester L.
• Granted Patent: US 6,969,369 B2
• Time in Patent Office: Days
• US Class Current: 604/66
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61M 2205/3523 using telemetric means
• CPC Class Codes: A61M 2210/125 Heart
• CPC Class Codes: A61M 2230/30 Blood pressure A61M2230/04 takes precedence
• CPC Class Codes: A61M 5/14276 specially adapted for implantation
• CPC Class Codes: A61M 5/1723 using feedback of body parameters, e.g. blood-sugar, pressure measurement of body parameters A61B5/00

Abstract

The invention is directed to techniques for monitoring the condition of a patient, such as a patient having congestive heart failure, and appropriately modifying the patient'"'"'s drug therapy as a function of a pressure in the patient'"'"'s heart, such as the estimated pulmonary artery diastolic pressure. The drugs may be administered by an implanted drug delivery device. The drug selection, the drug dosage or both may be controlled as a function of the pressure and/or the activity level of the patient.

Claims

1. An implantable medical device comprising:

a pressure monitor that estimates a pulmonary artery diastolic pressure as a function of a pressure in a heart of a patient; and

a processor that selects a dosage that corresponds to the estimated pulmonary artery diastolic pressure.

2. The device of claim 1, wherein the processor selects the dosage that corresponds to the estimated pulmonary artery diastolic pressure from a look-up table that maps dosages to estimated pulmonary artery diastolic pressures.

3. The device of claim 1, wherein the processor selects the dosage that corresponds to the estimated pulmonary artery diastolic pressure as a function of an equation that relates dosage to estimated pulmonary artery diastolic pressure.

4. The device of claim 1, wherein the device is implanted in the abdomen of a patient.

5. The device of claim 1, further comprising a pressure sensor that generates a pressure signal as a function of a pressure in the heart of the patient, and

wherein the pressure monitor estimates the pulmonary artery diastolic pressure as a function of the pressure signal.

6. The device of claim 5, wherein the pressure sensor includes one of a capacitive absolute pressure sensor, a piezoelectric crystal transducer and a piezoresistive pressure transducer.

7. The device of claim 5, wherein the pressure sensor is disposed in a right ventricle of the heart of the patient.

8. The device of claim 5, wherein the pressure monitor estimates the pulmonary artery diastolic pressure by identifying a pressure value at a point of maximum slope of the pressure signal.

9. The device of claim 5, wherein the pressure monitor comprises a differentiating circuit that generates a differential signal that is representative of a first derivative of the pressure signal, and

wherein the pressure monitor estimates the pulmonary artery diastolic pressure as a function of the differential signal.

10. The device of claim 5, wherein the pressure monitor comprises a differentiating circuit that generates a differential signal that is representative of a second derivative of the pressure signal, and

wherein the pressure monitor estimates the pulmonary artery diastolic pressure as a function of the differential signal.

11. The device of claim 1, further comprising a drug delivery device that delivers a drug to the patient,

wherein the processor generates a control signal as a function of the selected dosage, and

wherein the drug delivery device receives the control signal and delivers the drug to the patient at the selected dosage as a function of the control signal.

12. The device of claim 11, wherein the drug delivery device comprises:

a reservoir configured to receive and store the drug; and

an infusion apparatus that delivers the drug to an infusion site in the body of the patient.

13. The device of claim 12, wherein the infusion site is one of the subclavian vein, superior vena cava and fatty tissue of the body of the patient.

14. The device of claim 12, wherein the drug delivery device further comprises a pump that delivers the drug from the reservoir to a proximal end of the infusion apparatus.

15. The device of claim 11, wherein the drug is a drug that increases cardiac output.

16. The device of claim 11, wherein the drug is a drug that has a positive inotropic effect on the heart of the patient.

17. The device of claim 11, wherein the drug includes one of digitalis, digoxin, digitoxin, dopamine, dobutamine, milrinone and amrinone.

18. The device of claim 1, further comprising an activity sensor that generates an activity signal as a function of the patient'"'"'s activity,

wherein one of the pressure monitor and the processor measure a heart rate as a function of electrical activity within the heart, and

wherein the processor selects a dosage that corresponds to the estimated pulmonary artery diastolic pressure as a function of at least one of the activity signal and the measured heart rate.

19. The device of claim 1, further comprising an input/output device coupled to the processor, the input/output device configured to exchange information between a person and the processor.

44. The method of claim 38, wherein estimating the pulmonary artery diastolic pressure comprises estimating the pulmonary artery diastolic pressure each cardiac cycle.

52. The method of claim 51, further comprising:

receiving a range of pulmonary artery diastolic pressure values; and

receiving the corresponding at least one of the first drug and the second drug for each pulmonary artery diastolic pressure value in the range.

53. The method of claim 52, further comprising storing the received range of pulmonary artery diastolic pressure values and corresponding at least one of the first drug and the second drug in memory.

20. An implantable medical device comprising:

a pressure monitor that estimates a pulmonary artery diastolic pressure as a function of a pressure in a heart of a patient; and

a processor that selects a drug that corresponds to the estimated pulmonary artery diastolic pressure.

21. The device of claim 20, wherein the processor selects the drug that corresponds to the estimated pulmonary artery diastolic pressure from a look-up table that maps drugs to estimated pulmonary artery diastolic pressures.

22. The device of claim 20, wherein the device is implanted in the abdomen of a patient.

23. The device of claim 20, further comprising a pressure sensor that generates a pressure signal as a function of a pressure in the heart of the patient, and

wherein the pressure monitor estimates the pulmonary artery diastolic pressure as a function of the pressure signal.

24. The device of claim 23, wherein the pressure sensor includes one of a capacitive absolute pressure sensor, a piezoelectric crystal transducer and a piezoresistive pressure transducer.

25. The device of claim 23, wherein the pressure sensor is disposed in a right ventricle of the heart of the patient.

26. The device of claim 23, wherein the pressure monitor estimates the pulmonary artery diastolic pressure by identifying a pressure value at a point of maximum slope of the pressure signal.

27. The device of claim 23, wherein the pressure monitor comprises a differentiating circuit that generates a differential signal that is representative of a first derivative of the pressure signal, and

wherein the pressure monitor estimates the pulmonary artery diastolic pressure as a function of the differential signal.

28. The device of claim 23, wherein the pressure monitor comprises a differentiating circuit that generates a differential signal that is representative of a second derivative of the pressure signal, and

wherein the pressure monitor estimates the pulmonary artery diastolic pressure as a function of the differential signal.

29. The device of claim 20, further comprising a drug delivery device that delivers the selected drug to the patient,

wherein the processor generates a control signal as a function of the selected drug, and

wherein the drug delivery device receives the control signal and delivers the selected drug to the patient as a function of the control signal.

30. The device of claim 29, wherein the drug delivery device comprises:

a reservoir configured to receive and store the selected drug; and

an infusion apparatus, that delivers the selected drug to an infusion site.

31. The device of claim 30, wherein the infusion site is one of the subclavian vein, superior vena cava and fatty tissue of the body of the patient.

32. The device of claim 30, wherein the drug delivery device further comprises a pump that delivers the selected drug from the reservoir to a proximal end of the infusion apparatus.

33. The device of claim 20, wherein the selected drug is a drug that increases cardiac output.

34. The device of claim 20, wherein the selected drug is a drug that has a positive inotropic effect on the heart of the patient.

35. The device of claim 20, wherein the selected drug includes one of digitalis, digoxin, digitoxin, dopamine, dobutamine, milrinone and amrinone.

36. The device of claim 20, further comprising an activity sensor that generates an activity signal as a function of the patient'"'"'s activity,

wherein one of the pressure monitor and the processor measure a heart rate as a function of electrical activity within the heart, and

wherein the processor selects a drug that corresponds to the estimated pulmonary artery diastolic pressure as a function of at least one of the activity signal and the measured heart rate.

37. The device of claim 20, further comprising an input/output device coupled to the processor, the input/output device configured to exchange information between a person and the processor.

38. A method comprising:

estimating a pulmonary artery diastolic pressure as a function of a pressure in a heart of a patient;

selecting a drug therapy as a function of the estimated pulmonary artery diastolic pressure; and

controlling a drug delivery device to deliver a drug to the patient as a function of the selected drug therapy.

39. The method of claim 38, wherein selecting the drug therapy as a function of the estimated pulmonary artery diastolic pressure comprises selecting the drug therapy as a function of the estimated pulmonary artery diastolic pressure and an activity level of the patient.

40. The method of claim 38, wherein the pressure is the pressure in the right ventricle of the heart.

41. The method of claim 38, wherein estimating the pulmonary artery diastolic pressure as a function of a pressure comprises:

identifying a point of maximum slope in a pressure signal, the pressure signal a function of a the pressure in the heart of the patient; and

identifying the pressure value at the point of maximum slope in the pressure signal.

42. The method of claim 41, wherein identifying the point of maximum slope in the pressure signal comprises:

generating the first derivative of the pressure signal during a cardiac cycle; and

sensing the point on the pressure signal that corresponds to a maximum of the first derivative of the pressure signal is maximized.

43. The method of claim 41, wherein identifying the point of maximum slope in the pressure signal comprises:

sensing an R-wave of a cardiac cycle;

generating the second derivative of the pressure signal during the cardiac cycle; and

sensing the point on the pressure signal at which the second derivative of the pressure signal becomes negative after the R-wave.

45. The method of claim 38, wherein selecting the drug therapy as a function of the estimated pulmonary artery diastolic pressure comprises selecting a dosage for the drug delivered to the patient by the drug delivery device as a function of the estimated pulmonary artery diastolic pressure, and

wherein controlling the drug delivery device to deliver the drug as a function of the selected drug therapy comprises controlling a drug delivery device to deliver the drug at the selected dosage.

46. The method of claim 45, wherein selecting the dosage for the drug as a function of the estimated pulmonary artery diastolic pressure comprises:

storing a range of pulmonary artery diastolic pressure values and a dosage for the drug corresponding to each pulmonary artery diastolic pressure value in the range; and

selecting the dosage for the drug that corresponds to the estimated pulmonary artery diastolic pressure.

47. The method of claim 46, further comprising:

receiving a range of pulmonary artery diastolic pressure values; and

receiving the corresponding dosages.

48. The method of claim 47, further comprising storing the received range of pulmonary artery diastolic pressure values and the corresponding dosages in memory.

49. The method of claim 46, wherein the pulmonary artery diastolic pressure values correspond to the dosages according to an equation that defines a curve.

50. The method of claim 38, wherein selecting the drug therapy as a function of the estimated pulmonary artery diastolic pressure comprises selecting at least one of a first drug and a second drug as a function of the estimated pulmonary artery diastolic pressure, and

wherein controlling the drug delivery device to deliver the drug as a function of the selected drug therapy comprises controlling the drug delivery device to deliver the selected at least one of the first drug and the second drug.

51. The method of claim 50, wherein selecting at least one of a first drug and a second drug as a function of the estimated pulmonary artery diastolic pressure comprises:

storing a range of pulmonary artery diastolic pressure values and at least one of the first drug and the second drug corresponding to each pulmonary artery diastolic pressure value in the range; and

selecting the at least one of the first drug and the second drug that corresponds to the estimated pulmonary artery diastolic pressure.

54. The method of claim 50, wherein selecting the drug therapy as a function of the estimated pulmonary artery diastolic pressure further comprises selecting a dosage for a drug that is delivered to the patient, and

wherein controlling the drug delivery device to deliver the drug as a function of the selected drug therapy comprises controlling the drug delivery device to deliver the drug at the selected dosage.

55. A computer-readable medium comprising instructions that cause a processor to:

receive an estimated pulmonary artery diastolic pressure value;

select a drug therapy as a function of the estimated pulmonary artery diastolic pressure value; and

control a drug delivery device to deliver a drug to a patient as a function of the selected drug therapy.

56. The computer-readable medium of claim 55, further comprising instructions to cause the processor to:

receive a heart rate; and

receive an activity signal, the activity signal a function of the patient'"'"'s activity,

wherein the instructions that cause the processor to select the drug therapy as a function of the estimated pulmonary artery diastolic pressure comprises instructions that cause the processor to select the drug therapy as a function of the estimated pulmonary artery diastolic pressure, and at least one of the heart rate and the activity signal.

57. The computer readable medium of claim 55, wherein the instructions that cause the processor to select the drug therapy as a function of the estimated pulmonary artery diastolic pressure comprise instructions that cause the processor to select a dosage for the drug delivered to the patient as a function of the estimated pulmonary artery diastolic pressure, and

wherein the instructions that cause the processor to control the drug delivery device to deliver the drug to the patient as a function of the selected drug therapy comprise instructions that cause the processor to control the drug delivery device to deliver the drug at the selected dosage.

58. The computer readable medium of claim 55, wherein the instructions that cause the processor to select the drug therapy as a function of the estimated pulmonary artery diastolic pressure comprise instructions that cause the processor to select at least one of a first drug and a second drug as a function of the estimated pulmonary artery diastolic pressure, and

wherein the instructions that cause the processor to control the drug delivery device to deliver the drug to the patient as a function of the selected drug therapy comprise instructions that cause the processor to control the drug delivery device to deliver the selected at least one of a first drug and a second drug to the patient.

59. The computer readable medium of claim 58, wherein the instructions that cause the processor to select the drug therapy as a function of the estimated pulmonary artery diastolic pressure further comprise instructions that cause the processor to select a dosage for a drug delivered to the patient as a function of the estimated pulmonary artery diastolic pressure, and

wherein the instructions that cause the processor to control the drug delivery device to deliver the drug to the patient comprise instructions to cause the processor to control the drug delivery device to deliver the drug at the selected dosage.

60. An implantable medical device comprising:

means to estimate pulmonary artery diastolic pressure;

means to select a drug therapy as a function of the estimated pulmonary artery diastolic pressure; and

means to deliver a drug as a function of the selected drug therapy.

61. The device of claim 60, further comprising means to determine an activity level,

wherein the means to select the drug therapy selects the drug therapy as a function of the estimated pulmonary artery diastolic pressure and the determined activity level.

62. The device of claim 60, wherein the means to select a drug therapy comprises a means to select a dosage of the drug delivered by delivery means as a function of the estimated pulmonary artery diastolic pressure.

63. The device of claim 60, wherein the means to select a drug therapy comprises a means to select at least one of a first drug and a second drug as a function of the estimated pulmonary artery diastolic pressure.

64. The device of claim 63, wherein the means to select a drug therapy further comprises a means to select a dosage of the drug delivered by delivery means as a function of the estimated pulmonary artery diastolic pressure.