Leadless cardiac stimulation systems

• US 20060085039A1
• Filed: 10/20/2004
• Published: 04/20/2006
• Est. Priority Date: 10/20/2004
• Status: Active Grant

• Current Assignee: Boston Scientific Scimed (Boston Scientific Corporation)
• Original Assignee: Scimed Life Systems Incorporated (Boston Scientific Corporation)
• Inventors: Hastings, Roger N., Smith, Scott R., Lafontaine, Daniel M., Sadasiva, Anupama, Drassler, William J.
• Granted Patent: US 7,532,933 B2
• Time in Patent Office: Days
• US Class Current: 607/9
• CPC Class Codes: A61N 1/0587 Epicardial electrode systems; Endocardial electrodes piercing the pericardium
• CPC Class Codes: A61N 1/059 Anchoring means
• CPC Class Codes: A61N 1/3627 for treating a mechanical deficiency of the heart, e.g. congestive heart failure or cardiomyopathy
• CPC Class Codes: A61N 1/365 controlled by a physiological parameter, e.g. heart potential evoked response A61N1/371
• CPC Class Codes: A61N 1/37205 Microstimulators, e.g. implantable through a cannula
• CPC Class Codes: A61N 1/37217 characterised by the communication link, e.g. acoustic or tactile
• CPC Class Codes: A61N 1/37223 Circuits for electromagnetic coupling
• CPC Class Codes: A61N 1/37229 Shape or location of the implanted or external antenna
• CPC Class Codes: A61N 1/37241 providing test stimulations
• CPC Class Codes: A61N 1/37288 Communication to several implantable medical devices within one patient
• CPC Class Codes: A61N 1/37512 Pacemakers
• CPC Class Codes: A61N 1/3756 Casings with electrodes thereon, e.g. leadless stimulators
• CPC Class Codes: A61N 1/3787 from an external energy source

Abstract

Various configurations of systems that employ leadless electrodes to provide pacing therapy are provided. In one example, a system that provides multiple sites for pacing of myocardium of a heart includes wireless pacing electrodes that are implantable at sites proximate the myocardium using a percutaneous, transluminal, catheter delivery system. Each of the electrodes contains a source of electrical energy for pacing the myocardium and is adapted to receive electromagnetic energy from a source outside the myocardium. The system also includes a source adapted for placement outside the myocardium and that uses locally measured electrocardiograms to synchronize pacing of the heart by sending electromagnetic commands to the electrodes to pace the myocardium surrounding the electrodes. Also disclosed is various configurations of such systems, wireless electrode assemblies, and delivery catheters for delivering and implanting the electrode assemblies.

Claims

1. A system for providing multiple sites for pacing of myocardium of a heart, the system comprising:

wireless pacing electrodes that are implantable at sites proximate the myocardium using a percutaneous, transluminal, catheter delivery system, each of the electrodes containing a source of electrical energy for pacing the myocardium and further being adapted to receive electromagnetic energy from a source outside the myocardium;

a source adapted for placement outside the myocardium and that uses locally measured electrocardiograms to synchronize pacing of the heart by sending electromagnetic commands to the electrodes to pace the myocardium surrounding the electrodes.

2. The system of claim 1 wherein each of the electrodes contains a coil that is adapted to be inductively coupled to the source of electromagnetic energy.

3. The system of claim 2 wherein the source is further adapted to charge, by inductive coupling electromagnetic energy at a first frequency common to all wireless electrodes, capacitors within the electrodes to provide the source of electrical energy for use in pacing the myocardium.

4. The system of claim 2 wherein a source of local energy proximate the electrodes is used for pacing the myocardium and wherein the inductively coupled electromagnetic energy comprises a command to release the local energy to pace the surrounding myocardium.

5. The system of claim 4 in which the source of electrical energy for use in pacing the myocardium is a battery contained within the wireless electrode.

6. The system of claim 4 wherein the command to pace the myocardium is an electromagnetic signal inductively coupled to each coil in each wireless electrode from the source of electromagnetic energy at a frequency that is unique for each implanted wireless electrode.

7. The system of claim 1 wherein the source of electromagnetic energy comprises:

an electronic control circuit;

a transmit circuit;

a battery; and

an antenna.

8. The system of claim 7 wherein the source of electromagnetic is implantable subcutaneously within the patient being paced.

9. The system of claim 7 wherein the source is implantable within a chamber of the heart.

10. The system of claim 7 in which the antenna is implantable within a chamber of the heart and the electronic control circuit, the transmit circuit and the battery are implantable outside of the heart.

11. The system of claim 8 wherein the locally measured electrocardiogram is a voltage sensed by the electrodes proximate the source.

12. The system of claim 7 in which the battery is rechargeable.

13. The system of claim 8 in which energy to recharge the battery is electromagnetic energy inductively coupled to the antenna from a source outside the body.

14. The system of claim 7 in which the source is wearable outside of the body of the patient being paced.

15. The system of claim 14 in which the source is one of wearable in the patient'"'"'s clothing and contained in a disposable patch attached to the patient'"'"'s torso.

16. The system of claim 1 in which the local electrocardiogram is a voltage measured by one or more wireless electrodes and inductively communicated to the source.

17. The system of claim 1 in which the electrocardiogram is measured at the electrodes of a conventional pacemaker and communicated to the source outside the myocardium through an inductive link.

18. The system of claim 1 in which the electromagnetic energy commanding the electrodes to pace is received by one wireless electrode, and all other wireless electrodes pace local myocardium in response to changes in the electrocardiogram measured by each electrode at the site of each electrode.

19. The system of claim 1 in which neighboring wireless electrodes are inductively coupled to each other, and in which inductively received signals from neighboring wireless electrodes determine in part the time that said electrode paces local myocardium.

20. A catheter delivery system for implantation of wireless electrodes into the myocardium consisting of:

an elongate tube having a proximal end and a distal end and having a lumen passing therethrough;

an elongate rod having a proximal end and a distal end with a wireless electrode attached to its distal end, wherein the rod comprises a detachment mechanism to detach the wireless electrode from the rod following delivery of the wireless electrode to the myocardium, and wherein the rod with an attached wireless electrode is passable through the tube for delivery to the myocardium.

21. The catheter delivery system of claim 20 in which said elongate tube contains a steering mechanism to aid in placement of the distal end of the tube against a selected site on the wall of the heart.

22. The catheter delivery system of claim 20 in which the elongate tube contains an electrode at its distal end for sensing the local electrocardiogram at the selected site on the wall of the heart.

23. An implantable wireless electrode for pacing a site proximate the myocardium, the electrode comprising:

a source of electrical energy for use in pacing the myocardium;

receiver to receive electromagnetic energy from a source external of the myocardium; and

an attachment mechanism to attach the electrode to the myocardium to prevent migration.

24. The wireless electrode of claim 23 in which the source of electrical energy is derived from a physiological source of energy proximate the wireless electrode when implanted and that is transduced to electrical energy within the wireless electrode.

25. The wireless electrode of claim 23 in which the source of electrical energy is external to the myocardium and is inductively coupled to a coil that is proximate to and connected to the wireless electrode.

26. The wireless electrode of claim 25 in which the coil resides within the wireless electrode.

27. The wireless electrode of claim 25 in which the coil resides proximate the myocardium but outside of the wireless electrode.

28. The wireless electrode of claim 23 in which the receiver is a coil that is proximate to and connected to the wireless electrode.

29. The wireless electrode of claim 28 in which the received electromagnetic energy is a signal commanding the wireless electrode to deliver the source of electrical energy to pace the surrounding myocardium.

30. The wireless electrode of claim 29 in which the signal comprises electromagnetic energy having a frequency that is unique for each wireless electrode.

31. The wireless electrode of claim 29 in which the source of electrical energy is inductively coupled from a source external to the myocardium and stored on a capacitor contained within the wireless electrode.

32. The wireless electrode of claim 31 in which the capacitor is isolated from said coil when the capacitor voltage reaches a predetermined reference value.

33. The wireless electrode of claim 32 in which the predetermined voltage is less than 5 volts.

34. The wireless electrode of claim 33 for which a received signal can reset the predetermined voltage.

35. The wireless electrode of claim 31 in which a received signal commands the capacitor to discharge through surrounding myocardium.

36. The wireless electrode of claim 23 for which the attachment mechanism consists of one or more of tines, screws, barbs, hooks, and other fasteners that secure the body of the wireless electrode to the myocardium.

37. A method of delivering a wireless electrode to a location proximate the myocardium, the method comprising:

delivering an elongate member having a proximal end and a distal end and a lumen therethrough to a site proximate the myocardium;

delivering a wireless electrode attached to a rod through the lumen of the elongate member and into the myocardium proximate the distal end of the elongate member;

enabling a detachment mechanism to detach the rod from the wireless electrode; and

removing the rod and the catheter from the body of the patient.

38. The method of claim 37 in which a local electrocardiogram is measured at the distal end of the elongate member to determine the suitability of the site proximate the myocardium for pacing.

39. The method of claim 37 in which a tube is threaded over the rod but inside the lumen of the elongate member, and wherein the tube abuts the proximal end of the wireless electrode to push the electrode through the lumen.

40. The method of claim 37 in which a short burst of current is applied to the rod to heat and detach the rod at a spot on the rod having relatively high electrical resistance.

41. A method for synchronizing the contraction of a beating heart within a patient, the method comprising:

delivering a plurality of wireless electrodes to locations proximate the myocardium through a catheter delivery system;

monitoring a physiologic measure of heart function and selecting the timing and sequence of pacing of the plurality of wireless electrodes to optimize the measure of heart function; and

programming a pacing sequence into a controller.

42. The method of claim 41 in which the measure of heart function is cardiac output.

43. The method of claim 41 in which the measure of heart function is ejection fraction.

44. The method of claim 41 in which the measure of heart function is rate of pressure of diastole.

45. The method of claim 41 in which the controller is implanted subcutaneously into the patient.

46. The method of claim 41 in which the controller is worn in clothing or within a patch on the outside of the patient'"'"'s body.

47. The method of claim 41 for which the controller is implanted within a chamber of said heart.

48. A system for use with multiple body implanted wireless electrode assemblies that each have a pair of electrodes that are in contact with tissue of a body vessel, wherein each of the electrode assemblies may be charged by inductive coupling and subsequently discharged to deliver electrical energy across the pair of electrodes and thus across the contacted body tissue, the system comprising:

an implantable controller that senses electrical activity occurring within the body vessel and that determines from such sensing a timing of when electrical energy is to be delivered by each of the wireless electrode assemblies; and

a wireless transmitter and associated power source and antenna, wherein the transmitter is controllable by the implantable controller to charge, by inductive coupling, the storage capacitors of the implanted wireless electrode assemblies, and to provide wireless control signals that trigger the discharge of the storage capacitor in a specified one of the wireless electrode assemblies.

49. The system of claim 48 wherein the wireless transmitter and associated antenna are adapted to be implanted within a body.

50. The system of claim 49 wherein the wireless transmitter and the controller are provided within a single housing.

51. The system of claim 50 wherein the single housing is shaped for implantation between ribs.

52. The system of claim 51 wherein a battery provided within the single housing for providing power for the wireless transmitter and the controller is rechargeable.

53. The system of claim 50 wherein the single housing in shaped for placement on a ventricular septum.

54. The system of claim 53 wherein a battery provided within the single housing for providing power for the wireless transmitter and the controller is rechargeable.

55. The system of claim 48 wherein the wireless transmitter and associated antenna are adapted to be worn external of a body.

56. The system of claim 55 wherein the controller is adapted to be implanted within a body.

57. The system of claim 56 wherein the implantable controller communicates wirelessly with the external wireless transmitter and associated antenna.

58. The system of claim 57 wherein the implantable controller is programmable by external programmer.

59. The system of claim 48 wherein the wireless control signals provided by the wireless transmitter have multiple frequencies, wherein each of the multiple frequencies specifies one of the multiple wireless electrode assemblies.

60. The system of claim 48 wherein the body vessel is a heart.

61. The system of claim 48 wherein the controller has electrodes to sense electrical activity occurring within the body vessel.

62. A body implantable electrode assembly comprising:

a charge storage device operatively coupled to deliver stored charge discharged from the charge storage device across a pair of electrodes that are positionable to be in contact with body tissue;

a receiver coil that inductively couples an externally provided charging signal to charge the charge storage device and that receives externally provided wireless control signals; and

control circuitry that triggers the discharge of stored charge from the charge storage device upon receipt of a wireless control signal that indicates that the storage capacitor is to be discharged and that includes information that identifies the body implantable electrode assembly from among other such body implantable electrode assemblies.

63. The electrode assembly of claim 62 wherein the wireless control signal identifies the electrode assembly.

64. The electrode assembly of claim 62 wherein the electrode assembly is tuned to respond to a particular frequency of wireless control signal.

65. The electrode assembly of claim 64 wherein the electrode assembly has a filter that filters all but a selected frequency.

66. The electrode assembly of claim 62 further comprising a mechanism that secures the assembly to body tissue.

67. The electrode assembly of claim 62 wherein the electrode assembly does not include an internally generated power source.

68. A method of controlling the delivery of electrical signals from a plurality of wireless electrode assemblies that each have a pair of electrodes that are in contact with tissue of a body vessel, wherein each of electrode assemblies may be charged by inductive coupling and subsequently discharged to deliver electrical energy across the pair of electrodes and contacting body tissue, the method comprising:

wirelessly transmitting a charging signal that is received by each of the plurality of the wireless electrode assemblies to charge each of the storage capacitors of the plurality of wireless electrode assemblies at the same time; and

wirelessly transmitting control signals that are received by the wireless electrode assemblies to trigger the discharge of the storage capacitor in a selected one of the wireless electrode assemblies.

69. The method of claim 68 wherein the wirelessly transmitted control signals are transmitted at different frequencies, wherein one of the different frequencies identifies the selected one of the wireless electrode assemblies.

70. A catheter for manipulating a body implantable wireless electrode assembly, the catheter comprising:

an elongate tube with a lumen extending longitudinally therethrough to an opening at a distal end of the tube, wherein the lumen is sized so that a wireless electrode assembly may be moved through the tube lumen and out the distal opening of the tube;

an elongate member that slidably fits within the tube lumen and that is controllable to move a seed electrode distally within the tube lumen and out the distal opening of the tube lumen for positioning within the lumen body, the elongate member having a lumen extending longitudinally therethrough and constructed so that a lead that is detachably connected to the seed-type electrode of the seed-type electrode assembly extends proximally through the elongate member lumen and out a proximal port of the catheter so that electrical signals sensed by the electrode are provided external of the body.

71. A body implantable wireless electrode assembly comprising:

a pair of electrodes that contact tissue of a vessel;

securing mechanism that secures the assembly to body tissue in a selected position of the vessel;

a lead that is detachably connected to one of the pair of electrodes such that during an implantation procedure, the lead extends outside the body and allows electrical activity sensed by the connected electrode to be externally monitored; and

a detachment mechanism that when actuated detaches the lead from the wireless electrode assembly.

72. The wireless electrode assembly of claim 71 further comprising a lead connected to one of the pair of electrodes that first contacts tissue during an implantation procedure.

73. The wireless electrode assembly of claim 71 wherein:

one of the pair of electrodes is provided on one end of the electrode assembly; and

the electrode assembly has an electrical conductor extending within the assembly to an opposite end of the assembly.

74. The wireless electrode assembly of claim 71 wherein the lead is physically connected to the conductor.