Wireless ECG in implantable devices

• US 20050197674A1
• Filed: 03/05/2004
• Published: 09/08/2005
• Est. Priority Date: 03/05/2004
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Zhang, Geng, McCabe, Aaron, Scheiner, Avram, Ni, Quan, Daum, Douglas R.
• Granted Patent: US 7,299,086 B2
• Time in Patent Office: Days
• US Class Current: 607/9
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/329 Load diagnosis, e.g. cardiac stress tests
• CPC Class Codes: A61N 1/365 controlled by a physiological parameter, e.g. heart potential evoked response A61N1/371
• CPC Class Codes: A61N 1/3756 Casings with electrodes thereon, e.g. leadless stimulators

Abstract

An implantable medical device such as an implantable pacemaker or implantable cardioverter/defibrillator includes a programmable sensing circuit providing for sensing of a signal approximating a surface electrocardiogram (ECG) through implanted electrodes. With various electrode configurations, signals approximating various standard surface ECG signals are acquired without the need for attaching electrodes with cables onto the skin. The various electrode configurations include, but are not limited to, various combinations of intracardiac pacing electrodes, portions of the implantable medical device contacting tissue, and electrodes incorporated onto the surface of the implantable medical device.

Claims

1. A cardiac rhythm management system comprising:

a plurality of implantable electrodes including at least a first electrode and a second electrode selectable for sensing a cardiac signal approximating a surface electrocardiogram (ECG); and

an implantable medical device including;

a sensing circuit including;

a first sense input and a second sense input being a pair of differential inputs for sensing the cardiac signal approximating the surface ECG;

a gain programmable for at least a surface ECG gain selectable for sensing the cardiac signal approximating the surface ECG and an electrogram gain selectable for sensing an intracardiac electrogram; and

a frequency response programmable for at least a surface ECG pass band selectable for sensing the cardiac signal approximating the surface ECG and an intracardiac electrogram pass band selectable for sensing an intracardiac electrogram;

a processor to control the operation of the sensing circuit, the processor including a command receiver to receive an ECG acquisition command; and

a programmable sense interface providing at least a first electrical connection and a second electrical connection in response to the ECG acquisition command, the first electrical connection connecting the first electrode to the first sense input, the second electrical connection connecting the second electrode to the second sense input.

2. The system of claim 1, wherein the surface ECG pass band comprises a low cutoff frequency programmable for 4 Hz or less.

3. The system of claim 2, wherein the low cutoff frequency of the surface ECG pass band is programmable for a value between about 0.1 Hz to 0.5 Hz.

4. The system of claim 2, wherein the surface ECG pass band comprises a high cutoff frequency programmable for 50 Hz or less.

5. The system of claim 1, wherein the frequency response comprises a low cutoff frequency and a high cutoff frequency, wherein at least one of the low cutoff frequency and the high cutoff frequency is programmable.

6. The system of claim 5, wherein the low cutoff frequency is programmable in a range of about 0.1 Hz to 30 Hz.

7. The system of claim 5, wherein the high cutoff frequency is programmable in a range of 30 Hz to 150 Hz.

8. The system of claim 1, further comprising:

a first pacing lead including a first proximal end and a first distal end; and

a second pacing lead having a second proximal end and a second distal end,

wherein the first electrode is at or near the first distal end and the second electrode is at or near the second distal end.

9. The system of claim 8, wherein:

the first pacing lead is an atrial pacing lead; and

the second pacing lead is a ventricular pacing lead.

10. The system of claim 9, wherein the ventricular pacing lead comprises a right ventricular lead.

11. The system of claim 9, wherein the ventricular pacing lead comprises a left ventricular lead.

12. The system of claim 9, wherein:

the first pacing lead includes at least a first tip electrode and a first ring electrode, the first tip electrode located at the first distal end, the first ring electrode located near the first distal end at a predetermined distance from the first tip electrode; and

the second pacing lead includes at least a second tip electrode and a second ring electrode, the second tip electrode located at the second distal end, the second ring electrode located near the second distal end at a predetermined distance from the second tip electrode,

wherein the first electrode is the first ring electrode and the second electrode is the second ring electrode.

13. The system of claim 1, further comprising:

a pacing lead including a proximal end and a distal end;

a hermetically sealed can to house a circuit including at least portions of the sensing circuit; and

a can electrode including one of at least a portion of the can and an electrode incorporated onto, and electrically insulated from, the can,

wherein the first electrode is at or near the distal end of the pacing lead and the second electrode is the can electrode.

14. The system of claim 13, wherein the pacing lead is a ventricular pacing lead.

15. The system of claim 14, wherein the pacing lead includes at least one tip electrode and one ring electrode, the tip electrode located at the distal end, the ring electrode located near the distal end at a predetermined distance from the tip electrode, wherein the first electrode is the ring electrode.

16. The system of claim 1, wherein the implantable medical device comprises a hermetically sealed can to house an implant circuit including at least portions of the sensing circuit.

17. The system of claim 16, wherein the implantable medical device comprises a header attached to the can, the header including connectors providing for electrical access to the implant circuit.

18. The system of claim 17, wherein the implantable medical device comprises:

at least one header electrode being an electrode incorporated onto the header; and

a can electrode including one of at least a portion of the can and an electrode incorporated onto, and electrically insulated from, the can,

wherein the first electrode is the at least one header electrode and the second electrode is the can electrode.

19. The system of claim 18, wherein the implantable medical device comprises an impedance sensor, and wherein the at least one header electrode comprises an indifferent electrode of the impedance sensor.

20. The system of claim 19, wherein the impedance sensor is a respiratory sensor sensing a minute ventilation.

21. The system of claim 17, wherein the implantable medical device comprises:

a telemetry antenna; and

a can electrode including one of at least a portion of the can and an electrode incorporated onto, and electrically insulated from, the can,

wherein the first electrode includes at least a portion of the telemetry antenna functions and the second electrode is the can electrode.

22. The system of claim 21, wherein the telemetry antenna projects from the header and extends along a portion of the can.

23. The system of claim 17, wherein the can comprises an outer surface, and wherein the first electrode and the second electrode comprise two concentric electrodes incorporated onto the outer surface of the can.

24. The system of claim 23, wherein the at least two concentric electrodes comprise an inner electrode and an outer electrode, wherein the first electrode is the inner electrode and the second electrode is the outer electrode.

25. The system of claim 23, wherein the inner electrode includes a circular shaped electrode, and outer electrode includes a ring shaped electrode.

26. The system of claim 23, wherein the inner electrode includes a circular shaped electrode, and outer electrode includes an electrode approximating a contour of the can.

27. The system of claim 1, wherein the processor comprises a detector to detect a predetermined condition and produces the ECG acquisition command when the predetermined condition is detected.

28. The system of claim 27, wherein the processor further comprises a detection timer coupled to the detector, the detection timer activating and timing the detection of the predetermined condition based on a built-in or programmable schedule.

29. The system of claim 1, further comprising an external system communicatively coupled to the implantable medical device via telemetry, the external system including a user input device to receive the ECG acquisition command.

30. The system of claim 29, wherein the implantable medical device comprises an implant telemetry module to transmit the sensed cardiac signal out of the implantable medical device and a memory circuit including an ECG storage to store the sensed cardiac signal, and wherein the external system comprises an external telemetry module to receive the sensed cardiac signal and a display to visually present the sensed cardiac signal.

31. The system of claim 30, wherein the external system comprises a programmer.

32. The system of claim 30, wherein the external system comprises a patient management system including:

an external device communicatively coupled to the implantable medical device via telemetry;

a network coupled to the external device; and

a remote device coupled to the network.

33. The system of claim 32, wherein the remote device comprises the user input device and the display.

34. An implantable medical device comprising:

a sensing circuit programmable for a frequency response suitable for sensing a surface electrocardiogram (ECG), the sensing circuit including a first sense input and a second sense input being a pair of differential inputs for sensing a cardiac signal;

a hermetically sealed can to house an implant circuit including at least portions of the sensing circuit, the can having an outer surface subject to contact with body tissue; and

at least two concentric electrodes incorporated onto the outer surface of the can, the at least two concentric electrodes including an inner electrode and an outer electrode,

wherein the inner electrode is coupled to the first sense input, and the outer electrode is coupled to the second sense input.

35. The implantable medical device of claim 34, further comprising a processor to control the operation of the sensing circuit, the processor including a command receiver to receiver an ECG acquisition command and produces an ECG acquisition signal to start sensing the cardiac signal.

36. The implantable medical device of claim 35, further comprising a programmable sense interface providing electrical connections between the inner electrode and the first sense input and between the outer electrode and the second sense input when the ECG acquisition signal is present.

37. The implantable medical device of claim 34, wherein the inner electrode includes a circular shaped electrode, and outer electrode includes a ring shaped electrode.

38. The implantable medical device of claim 37, wherein the inner electrode has a surface area of about 15 to 50 squared millimeters, and the outer electrode has a surface area of about 50 to 150 squared millimeters.

39. The implantable medical device of claim 34, wherein the inner electrode includes a circular shaped electrode, and outer electrode includes an electrode approximating a contour of the can.

40. The implantable medical device of claim 39, wherein the inner electrode has a surface area of about 3 to 12 squared millimeters, and the outer electrode has a surface area of about 100 to 250 squared millimeters.

41. The implantable medical device of claim 34, wherein the sensing circuit comprises a band-pass filter having a surface ECG pass band having a programmable low cutoff frequency and a programmable high cutoff frequency.

42. The implantable medical device of claim 41, wherein the low cutoff frequency of the surface ECG pass band is programmable to a value between about 0.1 Hz to 0.5 Hz.

43. The implantable medical device of claim 41, wherein the high cutoff frequency of the surface ECG pass band is programmable to 50 Hz or less.

44. A cardiac rhythm management system comprising:

a plurality of implantable electrodes configured for sensing cardiac signals each approximating a surface electrocardiogram (ECG) vector; and

an implantable medical device including;

a sensing circuit including a plurality of sensing channels providing for simultaneous sensing of the cardiac signals;

a processor to control the operation of the sensing circuit, the processor including a command receiver to receive an ECG acquisition command; and

a programmable sense interface providing a plurality of pairs of electrical connections, each pair between one of the plurality of sensing channels and two electrodes selected from the plurality of implantable electrodes,

wherein the plurality of implantable electrodes are incorporated onto the implantable medical device.

45. The system of claim 44, wherein the implantable medical device comprises:

a hermetically sealed can to house an implant circuit including at least portions of the sensing circuit; and

a can electrode including one of at least a portion of the can and an electrode incorporated onto, and electrically insulated from, the can.

46. The system of claim 45, wherein the implantable medical device comprises a header attached to the can, the header including connectors providing for electrical access to the circuit.

47. The system of claim 46, wherein the implantable medical device further comprises at least a first header electrode being a first electrode incorporated onto the header.

48. The system of claim 47, wherein the implantable medical device further comprises a second header electrode being a second electrode incorporated onto the header.

49. The system of claim 48, wherein the programmable sensing circuit includes two or more of first, second, and third sensing channels, and wherein the programmable sense interface is adapted to provide for two or more of a first pair of electrical connections connecting the first and second header electrodes to the first sensing channel, a second pair of electrical connections connecting the first header electrode and the can electrode to the second sensing channel, and a third pair of electrical connections connecting the second header electrode and the can electrode to the third sensing channel.

50. The system of claim 47, wherein the implantable medical device further comprises a telemetry antenna, and wherein at least a portion of the telemetry antenna functions as an antenna electrode.

51. The system of claim 50, wherein the telemetry antenna projects from the header and extends along a portion of the can.

52. The system of claim 50, wherein the programmable sensing circuit includes two or more of first, second, and third sensing channels, and wherein the programmable sense interface is adapted to provide for two or more of a first pair of electrical connections connecting the first header electrode and the antenna electrode to the first sensing channel, a second pair of electrical connections connecting the first header electrode and the can electrode to the second sensing channel, and a third pair of electrical connections connecting the antenna electrode and the can electrode to the third sensing channel.

53. The system of claim 50, wherein the implantable medical device further comprises a second header electrode being a second electrode incorporated onto the header, and wherein the programmable sensing circuit includes two of more of first, second, third, fourth, fifth, and sixth sensing channels, and wherein the programmable sense interface is adapted to provide for two or more pairs of a first pair of electrical connections connecting the first header electrode and the second header electrode to the first sensing channel, a second pair of electrical connections connecting the first header electrode and the antenna electrode to the second sensing channel, a third pair of electrical connections connecting the first header electrode and the can electrode to the third sensing channel, a fourth pair of electrical connections connecting the second header electrode and the antenna electrode to the fourth sensing channel, a fifth pair of electrical connections connecting the second header electrode and the can electrode to the fifth sensing channel, and a sixth pair of electrical connections connecting the antenna electrode and the can electrode to the sixth sensing channel.

54. The system of claim 44, wherein the sensing channels each comprises a band-pass filter having a surface ECG pass band having a low cutoff frequency and a high cutoff frequency.

55. The system of claim 54, wherein the low cutoff frequency of the surface ECG pass band is programmable to a value between about 0.1 Hz to 0.5 Hz.

56. The system of claim 54, wherein the high cutoff frequency of the surface ECG pass band is programmable to 50 Hz or less.

57. A method for acquiring a signal approximating a surface electrocardiogram (ECG) using an implantable medical device, the method comprising:

receiving an ECG acquisition command;

programming a pass band of a sensing circuit of the implantable device after receiving the ECG acquisition command, the sensing circuit programmable for at least a surface ECG pass band and an intracardiac electrogram pass band, the programming including programming the pass band to the surface ECG pass band;

programming a sense interface of the implantable device to electrically connect at least two implantable electrodes to the sensing circuit after receiving the ECG acquisition command; and

sensing a cardiac signal after the programming the sensing circuit and the programming the sense interface.

58. The method of claim 57, wherein receiving the ECG acquisition command comprises receiving the ECG acquisition command from an external device via telemetry.

59. The method of claim 57, wherein receiving the ECG acquisition command comprises:

detecting a predetermined condition; and

generating the ECG acquisition command in response to a detection of the predetermined condition.

60. The method of claim 59, wherein detecting the predetermined condition comprises detecting an arrhythmia.

61. The method of claim 59, wherein detecting the predetermined condition comprises sensing an activity level.

62. The method of claim 59, wherein detecting the predetermined condition comprises detecting the predetermined condition according to a predetermined schedule.

63. The method of claim 62, wherein detecting the predetermined condition comprises detecting the predetermined condition on a predetermined periodic basis.

64. The method of claim 57, wherein programming the sensing circuit comprises programming a band-pass filter providing for the pass band.

65. The method of claim 57, wherein programming the pass band comprises programming a low cutoff frequency to about 0.1 Hz.

66. The method of claim 57, wherein programming the pass band comprises programming a low cutoff frequency to about 0.5 Hz.

67. The method of claim 57, wherein programming the pass band comprises programming a high cutoff frequency to about 100 Hz.

68. The method of claim 57, wherein programming the pass band comprises programming a high cutoff frequency to about 50 Hz or less.

69. The method of claim 57, further comprising programming a gain of the sensing circuit after receiving the ECG acquisition command, the sensing circuit programmable for at least a surface ECG gain and an intracardiac electrogram gain, the programming including programming the gain to the surface ECG gain.

70. The method of claim 57, wherein programming the sense interface comprises programming the sense interface to electrically connect at least two electrodes selected from a plurality of implantable electrodes to the sensing circuit, the plurality of electrodes including at least two or more of:

a ring electrode of an atrial pacing lead;

a ring electrode of an ventricular pacing lead;

one or more electrodes incorporated into a header of the implantable medical device;

a can electrode including one of at least a portion of a conductive can housing electronics of the implantable medical device and an electrode incorporated onto, and electrically insulated from, the conductive can;

a portion of an antenna providing for radio-frequency telemetry for the implantable medical device;

an inner electrode of a plurality of concentric electrodes incorporated onto the conductive can; and

one or more outer electrodes of the plurality of concentric electrodes incorporated onto the conductive can.

71. The method of claim 57, wherein:

programming the pass band comprises programming a plurality of sensing channels each programmable for at least the surface ECG pass band and the intracardiac electrogram pass band, the programming including programming the pass band of each of the plurality of sensing channels to the surface ECG pass band; and

programming the sense interface comprises programming the sense interface to electrically connect a plurality of electrode pairs each to one of the plurality of sensing channels after receiving the ECG acquisition command; and

further comprising sensing the cardiac signal and one or more additional cardiac signals each approximating a vector of the surface ECG after the programming the sensing circuit and the programming the sense interface.

72. The method of claim 71, wherein programming the sense interface comprises programming the sense interface to electrically connect the plurality of electrode pairs each to one of the plurality of sensing channels, the plurality of electrode pairs selected from plurality of electrodes including at least three or more of:

one or more electrodes incorporated into a header of the implantable medical device;

a can electrode including one of at least a portion of a conductive can housing electronics of the implantable medical device and an electrode incorporated onto, and electrically insulated from, the conductive can; and

a portion of an antenna providing for radio-frequency telemetry for the implantable medical device.

73. The method of claim 72, wherein programming the sense interface comprises programming the sense interface to electrically connect the plurality of electrode pairs each to one of the plurality of sensing channels, the plurality of electrode pairs selected from plurality of electrodes including at least three or more of:

a ring electrode of an atrial pacing lead;

a ring electrode of an ventricular pacing lead;

one or more electrodes incorporated into a header of the implantable medical device;

a can electrode including one of at least a portion of a conductive can housing electronics of the implantable medical device and an electrode incorporated onto, and electrically insulated from, the conductive can;

a portion of an antenna providing for radio-frequency telemetry for the implantable medical device;

an inner electrode of a plurality of concentric electrodes incorporated onto the conductive can; and

one or more outer electrodes of the plurality of concentric electrodes incorporated onto the conductive can.

74. The method of claim 57, further comprising storing the sensed cardiac signal in the implantable medical device.

75. The method of claim 57, further comprising:

transmitting the sensed cardiac signal to an external system for real time display; and

displaying the sensed cardiac signal in real time.