Implantable medical lead

• US 20060064149A1
• Filed: 09/23/2004
• Published: 03/23/2006
• Est. Priority Date: 09/23/2004
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Reinke, James D., Belacazar, Hugo A., Ecker, Robert M.
• Granted Patent: US 7,493,174 B2
• Time in Patent Office: Days
• US Class Current: 607/122
• CPC Class Codes: A61B 5/02055 Simultaneously evaluating both cardiovascular condition and temperature
• CPC Class Codes: A61B 5/145 Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissuemeasuring of blood pressure or blood flow A61B5/02; non-radiation detecting or locating of foreign bodies in blood A61B5/06
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61N 1/05 for implantation or insertion into the body, e.g. heart electrode A61N1/06 takes precedence
• CPC Class Codes: A61N 1/056 Transvascular endocardial electrode systems
• CPC Class Codes: A61N 1/36514 controlled by a physiological quantity other than heart potential, e.g. blood pressure controlled by two or more physical parameters A61N1/36585

Abstract

An implantable medical lead includes a device, such as a physiological sensor, that is coupled to one or more stimulation/sensing sensing conductors within the lead. When the implantable medical lead is coupled to an implantable medical device, the device carried by the lead both receives power from, and communicates with the implantable medical device via the one or more stimulation/sensing sensing conductors. Each of the one or more stimulation/sensing sensing conductors is also coupled to an electrode that is exposed to body tissue.

Claims

1. An implantable medical lead comprising:

a first electrode;

a second electrode;

a first electrical conductor electrically coupled to the first electrode;

a second electrical conductor electrically coupled to the second electrode; and

a sensor coupled across the first and second conductors in parallel with a current path between the first and second electrodes.

2. The implantable medical lead of claim 1, wherein the sensor senses at least one of oxygen saturation, partial pressure of oxygen, partial pressure of carbon dioxide, temperature, pressure, motion, vibration, glucose or potassium.

3. The implantable medical lead of claim 1, further comprising a connector that is configured to couple the conductors to circuitry within an implantable medical device that delivers electrical stimulation to a patient via the conductors and electrodes, wherein the sensor receives power from the implantable medical device via the conductors and communicates with the implantable medical device via the conductors.

4. The implantable medical lead of claim 3, wherein the electrodes comprise a tip electrode and a ring electrode for delivering cardiac pacing pulses from the implantable medical device to cardiac tissue and sensing electrical activity of a heart of the patient.

5. The implantable medical lead of claim 3, wherein the sensor includes an energy storage element that is coupled to the conductors and charged by a stimulation signal delivered from the implantable medical device to the patient via the conductors and electrodes.

6. The implantable medical lead of claim 5, wherein the energy storage element is charged by cardiac pacing pulses delivered from the implantable medical device to the patient via the conductors and electrodes.

7. The implantable medical lead of claim 3, wherein the sensor includes an energy storage element that is coupled to the conductors and charged by sub-threshold power pulses delivered from the implantable medical device via the conductors.

8. The implantable medical lead of claim 7, wherein the energy storage element is charged by biphasic sub-threshold pulses delivered from the implantable medical device via the conductors.

9. The implantable medical lead of claim 7, wherein the sensor uncouples the energy storage element from at least one of the conductors during delivery of stimulation by the implantable medical device.

10. The implantable medical lead of claim 9, wherein the sensor uncouples the energy storage element from at least one of the conductors in response to a signal from the implantable medical device indicating an upcoming delivery of stimulation.

11. The implantable medical lead of claim 3, wherein the sensor receives power from the implantable medical device during a first time period, and communicates with the implantable medical device during a second time period.

12. The implantable medical lead of claim 3, wherein the sensor communicates with the implantable medical device during a refractory period.

13. The implantable medical lead of claim 3, wherein the sensor selectively discharges a capacitor that is coupled to the conductors to transmit data to the implantable medical device.

14. The implantable medical lead of claim 3, wherein the sensor selectively couples a load to the conductors during delivery of stimulation by the implantable medical device to transmit data to the implantable medical device.

15. The implantable medical lead of claim 3, wherein the sensor communicates with the implantable medical device via sub-threshold pulses on the conductors.

16. The implantable medical lead of claim 15, wherein the sensor communicates with the implantable medical device by modulating at least one of a width of the sub-threshold pulses, an amplitude of the sub-threshold pulses, or a length of intervals between the sub-threshold pulses.

17. The implantable medical lead of claim 15, wherein the sensor maintains a clock that is synchronized to a clock maintained by the implantable medical device by the sub-threshold pulses.

18. The implantable medical lead of claim 3, wherein the sensor selectively uncouples at least one of the electrodes from a respective one of the conductors during a period between delivery of stimulation by the implantable medical device.

19. The implantable medical lead of claim 1, wherein the sensor includes an energy storage element, receives a signal from outside of a patient, and couples the energy storage element to the conductors in response to the signal.

20. An implantable medical device system comprising:

an implantable medical device; and

an implantable medical lead connected to the implantable medical device, wherein the implantable medical lead comprises;

a first electrode;

a second electrode;

a first electrical conductor electrically coupled to the implantable medical device and the first electrode;

a second electrical conductor electrically coupled to the implantable medical device and the second electrode; and

a sensor coupled across the first and second conductors in parallel with a current path between the first and second electrodes,

wherein the implantable medical device delivers stimulation to a patient via the conductors and electrodes, and the sensor receives power from the implantable medical device and communicates with the implantable medical device via the conductors.

21. The implantable medical device system of claim 20, wherein the first and second electrodes comprise a tip electrode and a ring electrode, and the implantable medical device comprises a cardiac pacemaker that delivers cardiac pacing pulses to cardiac tissue and senses electrical activity of a heart of the patient via the electrodes.

22. The implantable medical device system of claim 20, wherein the sensor senses at least one of oxygen saturation, partial pressure of oxygen, partial pressure of carbon dioxide, temperature, pressure, motion, vibration, glucose or potassium.

23. The implantable medical device system of claim 20, wherein the implantable medical device delivers a stimulation signal to the patient via the electrodes, and the sensor includes an energy storage element that is coupled to the conductors and charged by the stimulation signal.

24. The implantable medical device system of claim 23, wherein the implantable medical device delivers cardiac pacing pulses to a cardiac tissue via the electrodes, and the energy storage element is charged by the cardiac pacing pulses.

25. The implantable medical device system of claim 23, wherein the implantable medical device increases an amplitude of the stimulation signal during charging of the energy storage element.

26. The implantable medical device system of claim 20, wherein the sensor includes an energy storage element that is coupled to the conductors, and the implantable medical device delivers sub-threshold power pulses on the conductors to charge the energy storage element.

27. The implantable medical device system of claim 26, wherein the implantable medical device delivers biphasic sub-threshold power pulses on the conductors to charge the energy storage element.

28. The implantable medical device system of claim 26, wherein the sensor uncouples the energy storage element from at least one of the conductors during delivery of stimulation by the implantable medical device.

29. The implantable medical device system of claim 28, wherein the implantable medical device provides a signal to the sensor via the conductors, the signal indicating an upcoming delivery of stimulation by the implantable medical device, and wherein the sensor uncouples the energy storage element from at least one of the conductors in response to the signal.

30. The implantable medical device system of claim 20, wherein the implantable medical device delivers power to the sensor during a first time period, and communicates with the sensor during a second time period.

31. The implantable medical device system of claim 20, wherein the implantable medical device at least one of delivers power to the sensor and communicates with the sensor during a refractory period of the patient.

32. The implantable medical device system of claim 20, wherein the sensor selectively discharges a capacitor that is coupled to the conductors to transmit data to the implantable medical device.

33. The implantable medical device system of claim 20, wherein the sensor selectively couples a load to the conductors during delivery of stimulation by the implantable medical device to transmit data to the implantable medical device, and the implantable medical device measures at least one of voltage, current, or impedance during delivery of stimulation to detect coupling of the load to the conductors.

34. The implantable medical device system of claim 20, wherein the sensor and the implantable medical device communicate via sub-threshold pulses on the conductors.

35. The implantable medical device system of claim 34, wherein the sensor and the implantable medical device communicate by modulating at least one of a width of the sub-threshold pulses, an amplitude of the sub-threshold pulses, or a length of intervals between the sub-threshold pulses.

36. The implantable medical device system of claim 34, wherein the sensor and the implantable medical device maintain respective clocks, and the clock maintained by the sensor is synchronized to a clock maintained by the implantable medical device by the sub-threshold pulses.

37. The implantable medical device system of claim 20, wherein the sensor selectively uncouples at least one of the electrodes from a respective one of the conductors during a period between delivery of stimulation by the implantable medical device.

38. The implantable medical device system of claim 20, wherein the implantable medical device suspends a function during at least one of delivery of power to the sensor or communication with the sensor.

39. The implantable medical device system of claim 38, wherein the implantable medical device suspends at least one of autocapture detection, lead impedance measurement, battery life estimation, thoracic impedance measurement, minute ventilation measurement, P-wave sensing, R-wave sensing, or T-wave, sensing.

40. The implantable medical device system of claim 20, wherein the sensor includes an energy storage element, receives a signal from outside of a patient, and couples the energy storage element to the conductors in response to the signal.

41. A method comprising:

delivering an electrical stimulation signal via an implantable medical lead; and

charging an energy storage element of a sensor carried by the implantable medical lead with the stimulation signal,

wherein the lead includes at least one electrode coupled to a conductor, the sensor is coupled to the conductor, and the stimulation signal is delivered via the conductor and the electrode.

42. The method of claim 41, wherein the implantable medical lead includes two electrodes, each of the electrodes is coupled to a respective one of two conductors, and the sensor is coupled to both of the conductors.

43. The method of claim 41, wherein delivering an electrical stimulation signal comprises delivering cardiac pacing pulses.

44. The method of claim 41, further comprising transmitting data from the sensor to the implantable medical device via the conductor.

45. The method of claim 44, wherein the sensor includes a capacitor that is coupled to the conductor, and transmitting data comprises selectively discharging the capacitor.

46. The method of claim 44, wherein transmitting data comprises selectively coupling a load to the conductor during delivery of stimulation via the implantable medical lead.

47. A method comprising:

uncoupling an energy storage element of a sensor that is carried by an implantable medical lead from a conductor of the lead during delivery of electrical stimulation from an implantable medical device to a patient via the conductor; and

charging the energy storage element with sub-threshold power pulses delivered by the implantable medical device via the conductor.

48. The method of claim 47, further comprising receiving a signal from the implantable medical device indicating an upcoming delivery of electrical stimulation, wherein uncoupling an energy storage element comprises uncoupling the energy storage element in response to the signal.

49. The method of claim 47, wherein charging the energy storage element with sub-threshold power pulses comprises charging the energy storage element with biphasic sub-threshold power pulses.

50. The method of claim 47, further comprising transmitting data from the sensor to the implantable medical device via sub-threshold communication pulses on the conductor.

51. The method of claim 50, further comprising receiving the sub-threshold power pulses at the sensor during a refractory period of the patient, wherein transmitting data from the sensor to the implantable medical device comprises transmitting data during the refractory period.

52. A method for powering and communicating with a sensor carried by an implantable medical lead that is connected to an implantable medical device, wherein the implantable medical lead includes at least one conductor that is coupled to an electrode and the sensor, the method comprising:

delivering power from the implantable medical device to the sensor via the conductor;

communicating with the sensor via the conductor; and

suspending a function of the implantable medical device during at least one of delivery of power to the sensor or communication with the sensor.

53. The method of claim 52, wherein suspending a function comprises suspending at least one of autocapture detection, lead impedance measurement, battery life estimation, thoracic impedance measurement, minute ventilation measurement, P-wave sensing, R-wave sensing, or T-wave sensing.

54. The method of claim 52, further comprising delivering stimulation from the implantable medical device to a patient via the conductor and the electrode.

55. The method of claim 54, wherein delivering power from the implantable medical device to the sensor comprises delivering stimulation from the implantable medical device to the patient, the method further comprising increasing an amplitude of the stimulation during delivery of power.

56. The method of claim 54, further comprising providing a signal to the sensor via the conductor, the signal indicating an upcoming delivery of stimulation by the implantable medical device, wherein the sensor disconnects an energy storage element from the conductor in response to the signal.

57. The method of claim 54, wherein communicating with the sensor comprises measuring at least one of voltage, current or impedance during delivery of stimulation to detect coupling of a load to the conductor by the sensor during delivery of stimulation.

58. The method of claim 52, wherein the implantable medical device comprises a cardiac pacemaker, and delivering power and communicating comprise delivering power and communicating during a refractory period of the patient.

59. An implantable medical device comprising:

signal generation circuitry that delivers power to a sensor carried by an implantable medical lead that is connected to the implantable medical device, wherein the lead includes at least one conductor that is coupled to an electrode and the sensor, and the signal generation circuitry delivers power to the sensor via the conductor; and

a processor to control delivery of power by the signal generation circuitry, communicate with the sensor via the conductor, and suspend a function of the implantable medical device during at least one of delivery of power to the sensor or communication with the sensor.

60. The implantable medical device of claim 59, wherein the processor suspends at least one of autocapture detection, lead impedance measurement, battery life estimation, thoracic impedance measurement, minute ventilation measurement, P-wave sensing, R-wave sensing, or T-wave sensing.

61. The implantable medical device of claim 59, further comprising a therapy delivery module that delivers stimulation to a patient via the conductor and the electrode.

62. The implantable medical device of claim 61,

wherein the therapy delivery module comprises the signal generation circuitry, and delivers power to the sensor as part of the delivered stimulation, and

wherein the processor controls the therapy delivery module to increase an amplitude of the stimulation during delivery of power.

63. The implantable medical device of claim 61, wherein the processor provides a signal to the sensor via the conductor, the signal indicating an upcoming delivery of stimulation by the therapy delivery module, and wherein the sensor disconnects an energy storage element from the conductor in response to the signal.

64. The implantable medical device of claim 63, wherein the therapy delivery module measures at least one of voltage, current, or impedance during delivery of stimulation, and the processor receives data from the sensor by detecting coupling of a load to the conductor by the sensor during delivery of stimulation based on the measured voltage, current, or impedance.

65. The implantable medical device of claim 59, wherein the implantable medical device comprises a cardiac pacemaker, and the processor controls delivery of power by the signal generation circuitry and communicates with sensor during a refractory period of the patient.

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

control delivery of power from an implantable medical device to a sensor carried by an implantable medical lead via a conductor of the lead that is coupled to an electrode of the lead and the sensor;

communicate with the sensor via the conductor; and

suspend a function of the implantable medical device during at least one of delivery of power to the sensor or communication with the sensor.

67. The computer-readable medium of claim 66, wherein the instructions that cause a programmable processor to suspend a function comprise instructions that cause a programmable processor to suspend at least one of autocapture detection, lead impedance measurement, battery life estimation, thoracic impedance measurement, minute ventilation measurement, P-wave sensing, R-wave sensing, or T-wave sensing.

68. The computer-readable medium of claim 66, further comprising instructions that cause a programmable processor to control delivery of stimulation from the implantable medical device to a patient via the conductor and the electrode.

69. The computer-readable medium of claim 68, further comprising instructions that cause a programmable processor to increase an amplitude of the stimulation during delivery of power.

70. The computer-readable medium of claim 68, further comprising instructions that cause a programmable processor to provide a signal to the sensor via the conductor, the signal indicating an upcoming delivery of stimulation by the implantable medical device, wherein the sensor disconnects an energy storage element from the conductor in response to the signal.

71. The computer-readable medium of claim 68, wherein the instructions that cause a programmable processor to communicate with the sensor comprise instructions that cause a programmable processor to:

measure at least one of voltage, current, or impedance during delivery of stimulation; and

detect coupling of a load to the conductor during delivery of stimulation by the sensor based on the measured voltage, current, or impedance.

72. The computer-readable medium of claim 66, wherein the implantable medical device comprises a cardiac pacemaker, and the instructions that cause a programmable processor to control delivery of power and communicate comprise instructions that cause a programmable processor to control delivery of power and communicate during a refractory period of the patient.

73. An implantable medical lead comprising:

a first electrode;

an electrical conductor electrically coupled to the first electrode; and

a sensor coupled to the conductor in series with a current path between the first electrode and a second electrode not carried by the lead,

wherein the sensor receives power from an implantable medical device and communicates with the implantable medical device via the conductor and the current path, and includes an energy storage element to store power received from the implantable medical device, and

wherein the implantable medical device at least one of delivers electrical stimulation to a patient or senses electrical activity within the patient by the via the conductor and the electrode.

74. The implantable medical lead of claim 73, wherein the first electrode comprises a tip electrode for delivering cardiac pacing pulses from the implantable medical device cardiac tissue and sensing electrical activity of a heart of the patient.

75. The implantable medical lead of claim 73, wherein the energy storage element is selectively coupled in parallel with the implantable medical device to receive power from the implantable medical device, and the sensor includes a communication module that is selectively coupled in parallel with the implantable medical device for communication with the implantable medical device.