Cardiac output measurement using dual oxygen sensors in right and left ventricles

• US 20030199956A1
• 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: Grandjean, Pierre A., Muhlenberg, Lambert, Struble, Chester L.
• Granted Patent: US 7,164,948 B2
• Time in Patent Office: Days
• US Class Current: 607/122
• CPC Class Codes: A61B 5/029 Measuring or recording blood output from the heart, e.g. minute volume A61B8/065 takes precedence
• CPC Class Codes: A61B 5/1459 invasive, e.g. introduced into the body by a catheter A61B5/1464 takes precedence
• CPC Class Codes: A61N 1/056 Transvascular endocardial electrode systems

Abstract

A pacemaker provides multi-chamber pacing with a pacing interval that can be programmed and adapted in response to cardiac output measurements for a given patient. In a typical embodiment, the pacemaker may provide pacing stimuli to both ventricles of a heart. In addition, the invention may include a measurement device that incorporates first and second blood oxygen saturation sensors for deployment in the left and right ventricle. The oxygen saturation sensors provide a differential measurement that can be used to calculate cardiac output in accordance with the Fick method. The oxygen saturation sensors may be carried by a common trans-septal lead that positions one of the sensors proximate the right ventricle and the other sensor proximate the left ventricle. Alternatively, the oxygen saturation sensors may be deployed via separate leads. Whether single or dual leads are used to carry the oxygen saturation sensors, a respective lead may optionally carry electrodes for sensing, pacing, or both.

Claims

1. An implantable cardiac lead comprising:

a lead body having a distal tip;

a first optical sensor carried by the lead body adjacent the distal tip, wherein the first optical sensor includes a first emitter oriented to emit light outward from the distal tip and a first receiver oriented to receive light reflected toward the distal tip; and

a second optical sensor carried by the lead body, wherein the second optical sensor includes a second emitter oriented to emit light laterally outward from a side of the lead body and a second receiver oriented to receive light reflected toward the side of the lead body.

2. The implantable cardiac lead of claim 1, wherein the lead body includes a transmissive membrane that permits emission and reception of light by the first and second optical sensors.

3. The implantable cardiac lead of claim 1, wherein each of the first and second emitters includes a first light emitting diode that emits infrared light and a second light emitting diode that emits red light.

4. The implantable cardiac lead of claim 1, wherein the second optical sensor is carried by the lead body at a distance from the distal tip, wherein the distance is selected such that the second optical sensor is exposed to the right ventricle of a heart upon positioning of the lead body through the septum to place the first optical sensor within the left ventricle.

5. The implantable cardiac lead of claim 1, further comprising at least one electrode formed on the lead body.

6. The implantable cardiac lead of claim 1, further comprising:

a first electrode carried adjacent the distal tip of the lead body; and

a second electrode carried by the lead body at a distance from the distal tip, wherein the distance is selected such that second electrode is in substantial conductive contact with the right ventricle of a heart upon positioning of the lead body through the septum to place the first electrode in substantial conductive contact with the left ventricle.

7. The implantable cardiac lead of claim 1, further comprising first and second electrodes carried by the lead body between the distal tip and the second optical sensor.

8. A cardiac output measurement system comprising:

a first optical sensor carried on a lead for deployment in the left ventricle of a patient to measure blood oxygen saturation in the left ventricle;

a second optical sensor carried on a lead for deployment in the right ventricle of the patient to measure blood oxygen saturation in the right ventricle;

a memory storing oxygen consumption data for the patient; and

a memory storing hemoglobin data for the patient; and

a processor that computes cardiac output according to the Fick method based on the measured blood oxygen saturation in the left ventricle, the measured blood oxygen saturation in the right ventricle, the oxygen consumption data, and the hemoglobin data.

9. The system of claim 8, further comprising an activity level sensor that senses an activity level of the patient, wherein the memory stores oxygen consumption data for different activity levels of the patient, and the processor computes the cardiac output based on oxygen consumption data in the memory that corresponds to the sensed activity level.

10. The system of claim 8, wherein the first and second optical sensors are carried on a common lead, the lead includes a lead body having a distal tip, and wherein:

the first optical sensor is carried by the lead body adjacent the distal tip, wherein the first optical sensor includes a first emitter oriented to emit light outward from the distal tip and a first receiver oriented to receive light reflected toward the distal tip, and

the second optical sensor includes a second emitter oriented to emit light laterally outward from a side of the lead body and a second receiver oriented to receive light reflected toward the side of the lead body.

11. The system of claim 10, wherein the lead body includes a transmissive membrane that permits emission and reception of light by the first and second optical sensors.

12. The system of claim 10, wherein each of the first and second emitters includes a first light emitting diode that emits infrared light and a second light emitting diode that emits red light.

13. The system of claim 10, wherein the second optical sensor is carried by the lead body at a distance from the distal tip, wherein the distance is selected such that the second optical sensor is exposed to the right ventricle of a heart upon positioning of the lead body through the septum to place the first optical sensor within the left ventricle.

14. The system of claim 10, further comprising at least one electrode formed on the lead body.

15. The system of claim 10, further comprising:

a first electrode carried adjacent the distal tip of the lead body; and

a second electrode carried by the lead body at a distance from the distal tip, wherein the distance is selected such that second electrode is in substantial conductive contact with the right ventricle of a heart upon positioning of the lead body through the septum to place the first electrode in substantial conductive contact with the left ventricle.

16. The system of claim 10, further comprising first and second electrodes carried by the lead body between the distal tip and the second optical sensor.

17. The system of claim 8, wherein the processor computes the cardiac output further based on a hemoglobin value determined for the patient.

18. An implantable medical device comprising:

a pulse generator that delivers a first pacing pulse to a left ventricle and a second pacing pulse to a right ventricle following a pacing interval;

an oxygen saturation monitor that monitors a first blood oxygen saturation level in the left ventricle and a second blood oxygen saturation level in the right ventricle; and

a processor that adjusts the pacing interval as a function of the first and second blood oxygen saturation levels.

19. The implantable medical device of claim 18, wherein:

the pulse generator delivers the first and second pacing pulses during a first cardiac cycle,

the oxygen saturation monitor monitors the oxygen saturation levels in the left and right ventricles during the first cardiac cycle, and

the pulse generator delivers third and fourth pacing pulses to the left and right ventricles, respectively, during a subsequent cardiac cycle with a pacing interval adjusted as a function of the first and second oxygen saturation levels monitored in the first cardiac cycle.

20. The implantable medical device of claim 18, further comprising a memory storing oxygen consumption data for the patient, wherein the processor computes cardiac output according to the Fick method based on the first and second blood oxygen saturation levels and the oxygen consumption data., and the hemoglobin data, and adjusts the pacing interval as a function of the computed cardiac output.

21. The implantable medical device of claim 20, further comprising an activity level sensor that senses an activity level of the patient, wherein the memory stores oxygen consumption data for different activity levels of the patient, and the processor computes the cardiac output based on oxygen consumption data in the memory that corresponds to the sensed activity level.

22. The implantable medical device of claim 20, wherein the oxygen saturation monitor includes:

a first optical sensor carried on a lead for deployment in the left ventricle of a patient to measure the blood oxygen saturation level in the left ventricle; and

a second optical sensor carried on a lead for deployment in the right ventricle of the patient to measure the blood oxygen saturation level in the right ventricle.

23. The implantable medical device of claim 20, wherein the first and second optical sensors are carried on a common lead, the lead includes a lead body having a distal tip, and wherein:

the first optical sensor is carried by the lead body adjacent the distal tip, wherein the first optical sensor includes a first emitter oriented to emit light outward from the distal tip and a first receiver oriented to receive light reflected toward the distal tip, and

the second optical sensor includes a second emitter oriented to emit light laterally outward from a side of the lead body and a second receiver oriented to receive light reflected toward the side of the lead body.

24. The implantable medical device of claim 23, wherein the lead body includes a transmissive membrane that permits emission and reception of light by the first and second optical sensors.

25. The implantable medical device of claim 23, wherein each of the first and second emitters includes a first light emitting diode that emits infrared light and a second light emitting diode that emits red light.

26. The implantable medical device of claim 23, wherein the second optical sensor is carried by the lead body at a distance from the distal tip, wherein the distance is selected such that the second optical sensor is exposed to the right ventricle of a heart upon positioning of the lead body through the septum to place the first optical sensor within the left ventricle.

27. The implantable medical device of claim 23, further comprising at least one electrode formed on the lead body.

28. The implantable medical device of claim 23, further comprising:

a first electrode carried adjacent the distal tip of the lead body; and

a second electrode carried by the lead body at a distance from the distal tip, wherein the distance is selected such that second electrode is in substantial conductive contact with the right ventricle of a heart upon positioning of the lead body through the septum to place the first electrode in substantial conductive contact with the left ventricle.

29. The implantable medical device of claim 23, further comprising first and second electrodes carried by the lead body between the distal tip and the second optical sensor.

30. The implantable medical device of claim 23, wherein the processor computes the cardiac output further based on a hemoglobin value determined for the patient.

31. A method comprising:

delivering a first pacing pulse to a left ventricle of a patient;

delivering a second pacing pulse to a right ventricle following a pacing interval;

monitoring a first blood oxygen saturation level in the left ventricle and a second blood oxygen saturation level in the right ventricle; and

adjusting the pacing interval as a function of the first and second blood oxygen saturation levels.

32. The method of claim 31, further comprising:

delivering the first and second pacing pulses during a first cardiac cycle;

monitoring the oxygen saturation levels in the left and right ventricles during the first cardiac cycle; and

delivering third and fourth pacing pulses to the left and right ventricles, respectively, during a subsequent cardiac cycle with a pacing interval adjusted as a function of the first and second oxygen saturation levels monitored in the first cardiac cycle.

33. The method of claim 31, further comprising computing cardiac output according to the Fick method based on the first and second blood oxygen saturation levels and oxygen consumption data determined for the patient, wherein adjusting the pacing interval includes adjusting the pacing interval as a function of the computed cardiac output.

34. The method of claim 33, further comprising sensing an activity level of the patient, and computing the cardiac output based on oxygen consumption data that corresponds to the sensed activity level.

35. The method of claim 33, further comprising sensing the blood oxygen saturation levels using:

a first optical sensor carried on a lead deployed in the left ventricle of a patient to measure the blood oxygen saturation level in the left ventricle; and

a second optical sensor carried on a lead deployed in the right ventricle of the patient to measure the blood oxygen saturation level in the right ventricle.

36. The method of claim 35, wherein the first and second optical sensors are carried on a common lead, the lead includes a lead body having a distal tip, and wherein:

the first optical sensor is carried by the lead body adjacent the distal tip, wherein the first optical sensor includes a first emitter oriented to emit light outward from the distal tip and a first receiver oriented to receive light reflected toward the distal tip, and

the second optical sensor includes a second emitter oriented to emit light laterally outward from a side of the lead body and a second receiver oriented to receive light reflected toward the side of the lead body.

37. The method of claim 36, wherein the lead body includes a transmissive membrane that permits emission and reception of light by the first and second optical sensors.

38. The method of claim 36, wherein each of the first and second emitters includes a first light emitting diode that emits infrared light and a second light emitting diode that emits red light.

39. The method of claim 36, wherein the second optical sensor is carried by the lead body at a distance from the distal tip, wherein the distance is selected such that the second optical sensor is exposed to the right ventricle of a heart upon positioning of the lead body through the septum to place the first optical sensor within the left ventricle.

40. The method of claim 36, further comprising at least one electrode formed on the lead body.

41. The method of claim 36, wherein the lead includes:

a first electrode carried adjacent the distal tip of the lead body; and

a second electrode carried by the lead body at a distance from the distal tip, wherein the distance is selected such that second electrode is in substantial conductive contact with the right ventricle of a heart upon positioning of the lead body through the septum to place the first electrode in substantial conductive contact with the left ventricle.

42. The method of claim 36, wherein the lead includes first and second electrodes carried by the lead body between the distal tip and the second optical sensor.

43. The method of claim 36, further comprising computing cardiac output based on a hemoglobin value determined for the patient.

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

control a pulse generator to deliver a first pacing pulse to a left ventricle of a patient, and deliver a second pacing pulse to a right ventricle following a pacing interval;

monitor a first blood oxygen saturation level in the left ventricle and a second blood oxygen saturation level in the right ventricle; and

adjust the pacing interval as a function of the first and second blood oxygen saturation levels.

45. The computer-readable medium of claim 44, wherein the instructions further cause the processor to:

control the pulse generator to deliver the first and second pacing pulses during a first cardiac cycle;

monitor the oxygen saturation levels in the left and right ventricles during the first cardiac cycle; and

control the pulse generator to deliver third and fourth pacing pulses to the left and right ventricles, respectively, during a subsequent cardiac cycle with a pacing interval adjusted as a function of the first and second oxygen saturation levels monitored in the first cardiac cycle.

46. The computer-readable medium of claim 44, wherein the instructions cause the processor to compute cardiac output according to the Fick method based on the first and second blood oxygen saturation levels and oxygen consumption data determined for the patient, wherein the pacing interval is adjusted as a function of the computed cardiac output.

47. The computer-readable medium of claim 44, wherein the instruction cause a processor to sense an activity level of the patient, and compute the cardiac output based on oxygen consumption data that corresponds to the sensed activity level.

48. The computer-readable medium of claim 44, wherein the instructions cause the processor to compute the cardiac output based on a hemoglobin value determined for the patient.

49. An implantable medical device comprising:

means for delivering a first pacing pulse to a left ventricle of a patient;

means for delivering a second pacing pulse to a right ventricle following a pacing interval;

means for monitoring a first blood oxygen saturation level in the left ventricle and a second blood oxygen saturation level in the right ventricle; and

means for adjusting the pacing interval as a function of the first and second blood oxygen saturation levels.

50. The implantable medical device of claim 49, further comprising:

means for delivering the first and second pacing pulses during a first cardiac cycle;

means for monitoring the oxygen saturation levels in the left and right ventricles during the first cardiac cycle; and

delivering third and fourth pacing pulses to the left and right ventricles, respectively, during a subsequent cardiac cycle with a pacing interval adjusted as a function of the first and second oxygen saturation levels monitored in the first cardiac cycle.

51. The implantable medical device of claim 49, further comprising means for computing cardiac output according to the Fick method based on the first and second blood oxygen saturation levels and oxygen consumption data determined for the patient, wherein the means for adjusting the pacing interval includes means for adjusting the pacing interval as a function of the computed cardiac output.

52. The implantable medical device of claim 51, further comprising means for sensing an activity level of the patient, wherein the means for computing computes the cardiac output based on oxygen consumption data that corresponds to the sensed activity level.

53. The implantable medical device of claim 51, the means for sensing the blood oxygen saturation levels includes:

a first optical sensor carried on a lead deployed in the left ventricle of a patient to measure the blood oxygen saturation level in the left ventricle; and

a second optical sensor carried on a lead deployed in the right ventricle of the patient to measure the blood oxygen saturation level in the right ventricle.

54. The implantable medical device of claim 53, wherein the first and second optical sensors are carried on a common lead, the lead includes a lead body having a distal tip, and wherein:

the first optical sensor is carried by the lead body adjacent the distal tip, wherein the first optical sensor includes a first emitter oriented to emit light outward from the distal tip and a first receiver oriented to receive light reflected toward the distal tip, and

the second optical sensor includes a second emitter oriented to emit light laterally outward from a side of the lead body and a second receiver oriented to receive light reflected toward the side of the lead body.

55. The implantable medical device of claim 54, wherein the lead body includes a transmissive membrane that permits emission and reception of light by the first and second optical sensors.

56. The implantable medical device of claim 54, wherein each of the first and second emitters includes a first light emitting diode that emits infrared light and a second light emitting diode that emits red light.

57. The implantable medical device of claim 54, wherein the second optical sensor is carried by the lead body at a distance from the distal tip, wherein the distance is selected such that the second optical sensor is exposed to the right ventricle of a heart upon positioning of the lead body through the septum to place the first optical sensor within the left ventricle.

58. The implantable medical device of claim 54, further comprising at least one electrode formed on the lead body.

59. The implantable medical device of claim 54, wherein the lead includes:

a first electrode carried adjacent the distal tip of the lead body; and

a second electrode carried by the lead body at a distance from the distal tip, wherein the distance is selected such that second electrode is in substantial conductive contact with the right ventricle of a heart upon positioning of the lead body through the septum to place the first electrode in substantial conductive contact with the left ventricle.

60. The implantable medical device of claim 54, wherein the lead includes first and second electrodes carried by the lead body between the distal tip and the second optical sensor.

61. The implantable medical device of claim 54, wherein the means for computing includes means for computing cardiac output based on a hemoglobin value determined for the patient.

62. A method comprising:

sensing blood oxygen saturation in the left ventricle of the patient using a first optical sensor placed in the left ventricle;

sensing blood oxygen saturation in the right ventricle of the patient using a second optical sensor placed in the right ventricle; and

computing cardiac output for the patient according to the Fick method based on the measured blood oxygen saturation in the left ventricle, the measured blood oxygen saturation in the right ventricle, and oxygen consumption data for the patient.

63. The method of claim 62, wherein the first and second optical sensors are carried by a common lead, the first optical sensor being disposed adjacent the distal end of the lead, and wherein placing the first and second optical sensors includes inserting the distal end of the lead into the septum between the left and right ventricles such that the first optical sensor is in substantial optical communication with blood in the left ventricle and the second optical sensor is in substantial optical communication with blood in the right ventricle.