Systems and methods for examining the electrical characteristic of cardiac tissue

• US 6,256,540 B1
• Filed: 07/07/1997
• Issued: 07/03/2001
• Est. Priority Date: 01/28/1994
• Status: Expired due to Term

• Current Assignee: EP Technology (Boston Scientific Corporation)
• Original Assignee: EP Technology (Boston Scientific Corporation)
• Inventors: Panescu, Dorin, Swanson, David K., Schwartzman, David S., Mirotznik, Mark S., Foster, Kenneth R.
• Primary Examiner(s): Nasser, Robert L.
• Application Number:
  US08/888,456
• Time in Patent Office: 1,457 Days
• Field of Search: 607/122, 607/116, 607/101, 606/41, 600/372-375, 600/508, 600/509, 600/512, 600/513, 600/515, 600/518, 600/547
• US Class Current: 607/122
• CPC Class Codes: A61B 18/00 Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body eye surgery A61F9/007; ear surgery A61F11/00
• CPC Class Codes: A61B 2562/043 in a linear array
• CPC Class Codes: A61B 5/05 Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves impedance plethysmography A61B5/0295; measuring movement of the entire body or parts thereof A61B5/11; detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof A61B5/24
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/0538 invasively, e.g. using a catheter
• CPC Class Codes: A61B 5/287 Holders for multiple electrodes, e.g. electrode catheters for electrophysiological study [EPS]
• CPC Class Codes: A61B 5/6855 with a distal curved tip
• CPC Class Codes: A61B 5/6858 with a distal basket, e.g. expandable basket
• CPC Class Codes: A61N 1/056 Transvascular endocardial electrode systems

Abstract

Systems and methods examine heart tissue morphology using three or more spaced apart electrodes, at least two of which are located within the heart in contact with endocardial tissue. The systems and methods transmit electrical current through a region of heart tissue lying between selected pairs of the electrodes, at least one of the electrodes in each pair being located within the heart. The systems and methods derive the electrical characteristic of tissue lying between the electrode pairs based, at least in part, upon sensing tissue impedances. The systems and methods make possible the use of multiple endocardial electrodes for taking multiple measurements of the electrical characteristics of heart tissue. Multiplexing can be used to facilitate data processing. The systems and methods also make possible the identification of regions of low relative electrical characteristics, indicative of infarcted tissue, without invasive surgical techniques.

Claims

1. A system for examining tissue within a heart, comprising:

at least three spaced apart electrodes,

an invasive catheter device for locating at least two of the electrodes within the heart for contact with endocardial tissue,

a generator operable in one mode for transmitting electrical current in a first path through a region of heart tissue between a first pair of the electrodes, at least one of which is within the heart, the generator being operable in another mode for transmitting electrical current in a second path through heart tissue in the region between a second pair of electrodes, at least one of which is within the heart, without substantially altering the position of the first pair of electrodes, and

a processor configured for deriving tissue electrical characteristics based, at least in part, upon sensing impedances of the endocardial tissue lying in the first and second paths, and further for deriving iso-characteristic data from the endocardial tissue electrical characteristics.

2. A system according to claim 1,

wherein the processor compares the derived electrical characteristic of the tissue lying in first path with the derived electrical characteristic of the tissue lying second path.

3. A system according to claim 2,

wherein the processor generates an output based upon the comparison of derived electrical characteristics.

4. A system according to claim 1,

wherein the processor derives the electrical characteristic by measuring voltages in the first and second paths and dividing the measured voltages by currents transmitted through the paths to derive the tissue impedances.

5. A system according to claim 4,

wherein the processor compares the derived impedance of the tissue lying in the first path with the derived impedance of the tissue lying in the second path.

6. A system according to claim 5,

wherein the processor generates an output based upon the comparison of the derived tissue impedances.

7. A system according to claim 1,

wherein the processor derives tissue resistivities of the tissue lying in the first and second paths.

8. A system according to claim 7,

wherein the processor compares the derived resistivity of the tissue lying in the first path with the derived resistivity of the tissue lying in the second path.

9. A system according to claim 8,

wherein the processor generates an output based upon the comparison of the derived tissue resistivities.

10. A system according to claim 1,

wherein the locating means establishes substantially simultaneous, constant contact between at least two of the electrodes and endocardial tissue.

11. A system according to claim 1, wherein the at least three spaced apart electrodes include at least two electrodes adapted to establish substantially simultaneous, constant contact with endocardial tissue, while at the same time at least a further electrode is adapted to lie outside of the heart.

12. A system according to claim 1,

wherein the locating means establishes substantially simultaneous, constant contact between all the electrodes and endocardial tissue.

13. A system according to claim 1,

wherein the locating means includes a catheter tube having a distal end that carries at least two of the electrodes.

14. A system according to claim 13, wherein the generator and processor include a multiplexer/demultiplexer element, at least a portion of which is carried by the catheter tube.

15. A system according to claim 13, wherein the generator and processor include a multiplexer/demultiplexer element, at least a portion of which is carried by the catheter tube.

16. A system according to claim 13, wherein the generator and processor include a multiplexer/demultiplexer element, at least a portion of which is carried by the catheter tube.

17. A system according to claim 1,

and further including means for emitting energy to ablate myocardial tissue within the heart.

18. A system for examining tissue within a heart, comprising:

a three dimensional array of spaced apart electrodes for contacting endocardial tissue in a selected position,

means for transmitting electrical current from the spaced apart electrodes in multiple paths through a region of heart tissue without altering the position of the array,

a processor configured for deriving electrical characteristics of endocardial tissue lying in the multiple paths based, at least in part, upon sensing endocardial tissue impedances in the multiple paths, and further for deriving iso-characteristic data from the endocardial tissue electrical characteristics, and

means for providing a computer output display graphically displaying the derived iso-characteristic data.

19. A system according to claim 18,

wherein the processing means compares the electrical characteristic derived for tissue lying in one of the multiple paths with the electrical characteristic derived for tissue lying in another one of the multiple paths.

20. A system according to claim 19,

wherein the processor generates an output based upon the comparison of the derived electrical characteristics.

21. A system according to claim 18,

wherein the processor derives the electrical characteristic for each of the multiple paths by measuring the voltages in each path and dividing the measured voltage by the measured current transmitted through the path to derive the tissue impedance in the path.

22. A system according to claim 18,

wherein the processor compares the derived tissue impedances of the multiple paths.

23. A system according to claim 22,

wherein the processor generates an output based upon the comparison of the derived tissue impedances.

24. A system according to claim 18,

wherein the processor derives tissue resistivities of the tissue lying in each of the multiple paths.

25. A system according to claim 24,

wherein the processor compares the derived tissue resistivities of the multiple paths.

26. A system according to claim 25,

wherein the processor generates an output based upon the comparison of the derived tissue resistivities.

27. A system according to claim, 18,

and further including a catheter tube having a distal end that carries the three dimensional array.

28. A system according to claim 27,

wherein the means for transmitting electric current and the processor includes a multiplexer/demultiplexer element at least a portion of which is carried by the catheter tube.

35. A system according to claim 27, wherein the at least three spaced apart electrodes include at least two electrodes adapted to establish substantially simultaneous, constant contact with endocardial tissue, while at the same time at least a further electrode is adapted to lie outside of the heart.

40. A system according to claim 27,

and further including means for emitting energy to ablate myocardial tissue within the heart.

29. A system for examining tissue within a heart, comprising:

at least three spaced apart electrodes,

an invasive catheter device for locating at least two of the electrodes within the heart for contact with endocardial tissue,

a generator operable in one mode for transmitting electrical current in a first path through a region of heart tissue between a first pair of the electrodes, at least one of which is within the heart, the generator being operable in another mode for transmitting electrical current in a second path through heart tissue in the region between a second pair of the electrodes, at least one of which is within the heart, without substantially altering the position of the first pair of electrodes,

a processor configured for deriving tissue electrical characteristics based, at least in part, upon sensing impedances of the endocardial tissue lying in the first and second paths, and further for deriving iso-characteristic data from the endocardial tissue electrical characteristics, and

means for generating a graphical output of the derived iso-characteristic data.

30. A system according to claim 29,

wherein the processor derives the electrical characteristic by measuring voltages in the first and second paths and dividing the measured voltages by currents transmitted through the paths to derive tissue impedances, and

wherein the generated output includes the derived tissue impedances in spatial relation to the first and second paths.

31. A system according to claim 29,

wherein the processor derives tissue resistivities of the tissue lying in the first and second paths, and

wherein the generated output includes the derived tissue resistivities in spatial relation to the first and second paths.

32. A system according to claim 29,

wherein the generated output comprises a tabular listing.

33. A system according to claim 29,

wherein the generated output comprises a graphic display.

34. A system according to claim 29,

wherein the locating means establishes substantially simultaneous, constant contact between at least two of the electrodes and endocardial tissue.

36. A system according to claim 29,

wherein the locating means establishes substantially simultaneous, constant contact between all the electrodes and endocardial tissue.

37. A system according to claim 29,

wherein the locating means includes a catheter tube having a distal end that carries at least two of the electrodes.

38. A system according to claim 29,

wherein the locating means includes a three dimensional structure for supporting at least two of the electrodes.

39. A system according to claim 38,

wherein the locating means includes a catheter tube having a distal end that carries the three dimensional structure.

41. A method for detecting an infarcted region within a heart, comprising:

transmitting electrical current in a first path through a region of heart tissue between a first pair of electrodes, at least one of which is located within the heart in contact with endocardial tissue,

transmitting electrical current in a second path through tissue in the region between a second pair of electrodes, at least one of which is located within the heart in contact with endocardial tissue, without substantially altering the location of the first pair of electrodes,

deriving electrical characteristics of endocardial tissue lying in the first and second paths based, at least in part, upon sensing impedances in the first and second paths,

deriving iso-characteristic data from the endocardial tissue electrical characteristics, the iso-characteristic data representative of the infarcted region, and

displaying a graphical representation of the heart with the infarcted region highlighted.

42. A method according to claim 41,

further comprising comparing the derived electrical characteristic of the first path with the derived electrical characteristic of the second path.

43. A method according to claim 42,

further comprising creating an output based upon the comparison of derived electrical characteristics.

44. A method according to claim 41,

further comprising creating an output of the derived electrical characteristics in spatial relation to the location of the first and second paths.

45. A method according to claim 41,

wherein, in the step of deriving the electrical characteristics, voltages are measured in the first and second paths and the voltage measured in each path is divided the measured current transmitted through the associated path to derive tissue impedances for the first and second paths.

46. A method according to claim 45, further comprising comparing the derived tissue impedances.

47. A method according to claim 46, further comprising creating an output based upon the comparison of the derived tissue impedances.

48. A method according to claim 46, further comprising creating an output of the derived tissue characteristics in spatial relation to the first and second paths.

49. A method according to claim 41,

wherein, in the step of deriving electrical characteristics, resistivities of tissue lying in the first and second paths are derived.

50. A method according to claim 49,

further comprising comparing the derived tissue resistivities.

51. A method according to claim 50,

further comprising creating an output based upon the comparison of the derived tissue resistivities.

52. A method according to claim 50,

further comprising creating an output of the derived tissue resistivities in spatial relation to the location of the first and second paths.

53. A method for detecting an infarcted region within a heart, comprising:

positioning an array of spaced apart electrodes in contact with a region of endocardial tissue in a desired position,

transmitting electrical current from the spaced apart electrodes in multiple paths through a region of heart tissue without altering the position of the array,

deriving electrical characteristics of tissue lying in the multiple paths based, at least in part, upon sensing endocardial tissue impedances in the multiple paths, the electrical characteristics representative of the infarcted region, and

displaying a graphical representation of the heart with a highlighted area thereon, the highlighted area indicating the infarcted region.

54. A method according to claim 53,

further comprising comparing the derived electrical characteristics of the multiple paths to each other.

55. A method according to claim 54,

further comprising creating an output based upon the derived electrical characteristics.

56. A method according to claim 54,

further comprising creating an output of the derived electrical characteristics in spatial relation to the multiple paths.

57. A method for examining tissue within the heart, comprising the steps of

positioning an array of electrodes in contact with a region of tissue in the heart, obtaining data from said electrodes relating to electrical characteristics of the region of tissue in the heart, and

providing a graphical representation of the region of tissue having a visually distinctive portion of said graphical representation corresponding to a selected value range of said data.