Systems and methods for examining the electrical characteristic of cardiac tissue

• US 6,370,435 B2
• Filed: 02/14/2001
• Issued: 04/09/2002
• Est. Priority Date: 01/28/1994
• Status: Expired due to Term

• Current Assignee: EP Technologies Incorporated (Boston Scientific Corporation)
• Original Assignee: EP Technologies Incorporated (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:
  US09/783,778
• Publication Number:
  US 20010018608A1
• Time in Patent Office: 419 Days
• Field of Search: 607/101, 607/116, 607/122, 606/41, 600/372-5, 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:

an invasive device for locating a plurality of electrodes within the heart for contact with heart tissue;

a generator operable in one mode for transmitting eletrical current in a first path through heart tissue in a region located between a first pair of electrodes, at one of which is carried by the invasive device with the heart, the generator being operable in mode for transmitting eletrical current in a second path through heart tissue in a region located between a second pair of eletrodes, at least one of which is carried by the invasive device within the heart; and

a processor configured for deriving eletrical characterics of the heart tissue based, at least in part, upon impedances of the respective heart tissue regions in the first and second paths, and further for deriving iso-characteristic data from the heart tissue impedances.

2. The system of claim 1,

wherein the first and second electrode pairs share an electrode located outside of the heart.

3. The system of claim 1,

wherein the first and second electrode pairs share an-electrode located inside the heart.

4. The system of claim 1,

wherein the first and second electrode pairs do not share an electrode.

5. A system according to claim 1,

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

6. A system according to claim 5,

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

7. A system according to claim 1,

wherein the processor measures voltages in the first and second paths, and divides the measured voltages by currents transmitted through the paths to derive the respective tissue impedances.

8. A system according to claim 7,

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

9. A system according to claim 1,

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

10. A system according to claim 9,

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

11. A system according to claim 1,

wherein the invasive device establishes substantially simultaneous, constant contact between all of the plurality of electrodes and heart tissue.

12. A system according to claim 1, wherein the generator and processor include a multiplexer/demultiplexer element, at least a portion of which is carried by the invasive device.

13. A system according to claim 1,

the generator operable in a further mode for emitting energy through at least one electrode to ablate myocardial tissue within the heart.

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

an invasive device for locating a three dimensional array of spaced apart electrodes for contacting heart 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 the heart tissue based at least, in part, upon impedances of the respective heart tissue regions in the multiple paths, and further for deriving iso-characteristic data from the heart tissue impedances; and

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

15. A system according to claim 14,

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

16. A system according to claim 15,

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

17. A system according to claim 14,

wherein the processor measures the voltages in each of the multiple paths and divides the measured voltages by currents transmitted through the paths to derive respective tissue impedance in the path.

18. A system according to claim 14,

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

19. A system according to claim 14,

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

20. A system according to claim 19,

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

21. A system according to claim 20,

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 invasive device.

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

an invasive device for locating a plurality of electrodes within the heart for contact with heart tissue, a generator operable in one mode for transmitting electrical current in a first path through heart tissue in a region located between a first pair of the electrodes, at least one of which is carried by the invasive device within the heart, the generator being operable in another mode for transmitting electrical current in a second path through heart tissue in a region between a second pair of the electrodes, at least one of which is carried by the invasive device within the heart, without substantially altering the position of the first pair of electrodes, and

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

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

23. A system according to claim 22,

wherein the processor measures voltages in the first and second paths, and divides the measured voltages by currents transmitted through the paths to derive the respective tissue impedances, and

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

24. A system according to claim 22,

wherein the processor derives tissue resistivities of the respective tissue regions 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.