Expandable-collapsible electrode structures made of electrically conductive material

• US 20030093069A1
• Filed: 06/11/2002
• Published: 05/15/2003
• Est. Priority Date: 01/19/1996
• Status: Active Grant

• Current Assignee: EP Technology (Boston Scientific Corporation)
• Original Assignee: EP Technology (Boston Scientific Corporation)
• Inventors: Kordis, Thomas F., Panescu, Dorin, Swanson, David K., Whayne, James G.
• Granted Patent: US 6,736,811 B2
• Time in Patent Office: Days
• US Class Current: 606/34
• CPC Class Codes: A61B 18/1492 having a flexible, catheter-like structure, e.g. for heart ablation A61B18/1477 takes precedence
• CPC Class Codes: A61B 2017/00053 Mapping
• CPC Class Codes: A61B 2017/00243 cardiac
• CPC Class Codes: A61B 2017/22051 with an inflatable part, e.g. balloon, for positioning, blocking, or immobilisation A61B2017/22048, A61B2017/3486 take precedence
• CPC Class Codes: A61B 2017/22061 for spreading elements apart
• CPC Class Codes: A61B 2018/00065 porous
• CPC Class Codes: A61B 2018/00083 low, i.e. electrically insulating
• CPC Class Codes: A61B 2018/00095 high, i.e. heat conducting
• CPC Class Codes: A61B 2018/00107 Coatings on the energy applicator
• CPC Class Codes: A61B 2018/00113 with foam
• CPC Class Codes: A61B 2018/00148 with metal
• CPC Class Codes: A61B 2018/00214 Expandable means emitting energy, e.g. by elements carried thereon
• CPC Class Codes: A61B 2018/0022 Balloons
• CPC Class Codes: A61B 2018/00267 having a basket shaped structure
• CPC Class Codes: A61B 2018/00839 Bioelectrical parameters, e.g. ECG, EEG
• CPC Class Codes: A61B 2018/1253 monopolar
• CPC Class Codes: A61B 2018/1472 for use with liquid electrolyte, e.g. virtual electrodes
• CPC Class Codes: A61B 2218/002 Irrigation
• CPC Class Codes: A61L 29/085 Macromolecular materials
• CPC Class Codes: A61L 29/145 Hydrogels or hydrocolloids
• CPC Class Codes: A61L 31/10 : Macromolecular materials
• CPC Class Codes: A61L 31/145 : Hydrogels or hydrocolloids
• CPC Class Codes: A61N 1/056 : Transvascular endocardial electrode systems
• CPC Class Codes: A61N 1/06 : for high-frequency therapy
• CPC Class Codes: C08L 1/02 : Cellulose; Modified cellulose

Abstract

Electrode assemblies and associated systems employ a nonporous wall having an exterior for contacting tissue. The exterior peripherally surrounds an interior area. The wall is essentially free of electrically conductive material. The wall is adapted to assume an expanded geometry having a first maximum diameter and a collapsed geometry having a second maximum diameter less than the first maximum diameter. The assemblies and systems include a lumen that conveys a medium containing ions into the interior area. An element free of physical contact with the wall couples the medium within the interior area to a source of electrical energy to enable ionic transport of electrical energy from the source through the medium to the wall for capacitive coupling to tissue contacting the exterior of the wall.

Claims

1. An electrode assembly comprising

a nonporous wall having an exterior for contacting tissue and an interior peripherally surrounding an interior area, the exterior of the wall being essentially free of electrically conductive material, a first electrically conductive element disposed within the interior of the wall, the wall being adapted to assume an expanded geometry having a first maximum diameter and a collapsed geometry having a second maximum diameter less than the first maximum diameter,

a lumen to convey a medium containing ions into the interior area, and

a second electrically conductive element free of physical contact with the first electrically conductive element that couples the medium within the interior area to a source of electrical energy to enable ionic transport of electrical energy from the source through the medium to the first electrically conductive element for capacitive coupling to tissue contacting the exterior of the wall.

4. An assembly according to claim 1 or 2 or 3

wherein the first electrically conductive element comprises an electrically conductive material deposited on at least a portion of the interior of the wall.

5. An assembly according to claim 4

wherein the electrically conductive material comprises a noble metal.

6. An assembly according to claim 4

wherein the electrically conductive material includes a material selected from the group consisting essentially of gold, platinum, platinum/iridium, and combinations thereof.

7. An assembly according to claim 1 or 2 or 3

wherein the medium comprises a hypertonic solution.

8. An assembly according to claim 7

wherein the hypertonic solution includes sodium chloride.

9. An assembly according to claim 8

wherein the sodium chloride is present in a concentration at or near saturation.

10. An assembly according to claim 8

wherein the sodium chloride is present in a concentration of up to about 9% weight by volume.

11. An assembly according to claim 1 or 2 or 3

wherein the capacitive coupling of the wall is expressed in the following relationship:

$\sqrt{R_{\mathrm{PATH}}^2+X_c^2}<<br><br>R_{\mathrm{TISSUE}}$$\text{where;<br><br>}$$R_{\mathrm{PATH}}=\frac{K}{S_E}<br><br>{\mathrm{\rho <br><br>}}_S$

 

and

K is a constant that depends upon geometry of the wall,

S_E is surface area of the first electrically conductive element, and

ρ

_S is resistivity of the medium containing ions, and where;

$X_C=\frac{1}{2<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{\pi <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{fC}}$

 

and

f is frequency of the electrical energy, and

$C=\mathrm{\varepsilon <br><br>}<br><br>\frac{S_B}{t}$

 

where;

ε

is the dielectric constant of wall,

S_B is the area of the interior area, and

t is thickness of the wall located between the medium containing ions and tissue, and

where R_TISSUE is resistivity of tissue contacting the wall.

12. An assembly according to claim 11 wherein R_TISSUE is about 100 ohms.

13. An assembly according to claim 1 or 2 or 3

wherein the first electrically conductive element comprises members assembled within the interior area to form a support structure underlying the wall.

14. An assembly according to claim 13

wherein the support structure comprises an electrically conductive, resilient mesh structure.

15. An assembly according to claim 13

wherein the support structure comprises a skeleton of flexible, electrically conductive spline elements.

16. An assembly according to claim 13

wherein the support structure comprises an open cell foam structure coated with electrically conductive material.

17. An assembly according to claim 13

wherein the support structure comprises a plastic material.

18. An assembly according to claim 13

wherein the support structure comprises elongated spline elements assembled in a circumferentially spaced relationship.

19. An assembly according to claim 1 or 2 or 3

and further including at least one temperature sensing element disposed on the wall.

2. An electrode assembly comprising

a nonporous wall having an exterior for contacting tissue and an interior peripherally surrounding an interior area, the exterior of the wall being essentially free of electrically conductive material, a first electrically conductive element disposed within the interior of the wall, the wall being adapted to assume an expanded geometry having a first maximum diameter and a collapsed geometry having a second maximum diameter less than the first maximum diameter,

a medium containing ions filling the interior area, and

a second electrically conductive element free of physical contact with the first electrically conducting element coupling the medium to a source of electrical energy to enable ionic transport of electrical energy from the source through the medium to the first electrically conductive element for capacitive coupling to tissue contacting the exterior of the wall.

3. An electrode assembly comprising

a nonporous wall having an exterior for contacting tissue and an interior peripherally surrounding an interior area, the exterior of the wall being essentially free of electrically conductive material, a first electrically conductive element disposed within the interior of the wall, the wall being adapted to assume an expanded geometry having a first maximum diameter and a collapsed geometry having a second maximum diameter less than the first maximum diameter,

a generator of radio frequency energy,

a fluid source holding a medium containing ions,

a lumen communicating with the interior area and the fluid source to convey the medium containing ions into the interior area,

a second electrically conductive element free of physical contact with the first electrically conductive element coupled to the generator to establish electrical contact between the medium within the interior area and the generator to enable ionic transport of radio frequency energy from the generator through the medium to the first electrically conductive element for capacitive coupling to tissue contacting the exterior of the wall.

20. A system for heating body tissue comprising

a catheter tube having a distal end,

a return electrode,

a fluid source of a medium containing ions,

a source of electrical energy,

an electrode on the distal end of the catheter tube comprising a nonporous wall having an exterior for contacting tissue and an interior peripherally surrounding an interior area, the exterior being essentially free of electrically conductive material, a first electrically conductive element disposed within the interior of the wall, the wall being adapted to assume an expanded geometry having a first maximum diameter and a collapsed geometry having a second maximum diameter less than the first maximum diameter, a lumen to convey the medium containing ions into the interior area, and a second electrically conductive element within the interior area free of physical contact with the first electrically conductive element, and

means for coupling the return electrode and the second electrically conductive element to the source of energy to enable ionic transport of electrical energy from the source through the medium to the first electrically conductive element for capacitive coupling to tissue to heat tissue located between the return electrode and the electrode.

23. A system according to claim 20 or 21 or 22

wherein the first electrically conductive element comprises an electrically conductive material deposited on at least a portion of the interior of the wall.

24. A system according to claim 23

wherein the electrically conductive material comprises a noble metal.

25. A system according to claim 23

wherein the electrically conductive material includes a material selected from the group consisting essentially of gold, platinum, platinum/iridium, and combinations thereof.

26. A system according to claim 20 or 21 or 22

wherein the medium comprises a hypertonic solution.

27. A system according to claim 26

wherein the hypertonic solution includes sodium chloride.

28. A system according to claim 27

wherein the sodium chloride is present in a concentration at or near saturation.

29. A system according to claim 27

wherein the sodium chloride is present in a concentration of up to about 9% weight by volume.

30. A system according to claim 20 or 21 or 22

wherein the capacitive coupling of the wall is expressed in the following relationship:

$\sqrt{R_{\mathrm{PATH}}^2+X_c^2}<<br><br>R_{\mathrm{TISSUE}}$$\text{where;<br><br>}$$R_{\mathrm{PATH}}=\frac{K}{S_E}<br><br>{\mathrm{\rho <br><br>}}_S$

 

and

K is a constant that depends upon geometry of the wall,

S_E is a surface area of the first electrically conductive element, and

ρ

_S is resistivity of the medium containing ions, and where;

$X_C=\frac{1}{2<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{\pi <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{fC}}$

 

and

f is frequency of the electrical energy, and

$C=\mathrm{\varepsilon <br><br>}<br><br>\frac{S_B}{t}$

 

where;

ε

is the dielectric constant of wall,

S_B is the area of the interior area, and

t is thickness of the wall located between the medium containing ions and tissue, and

where R_TISSUE is resistivity of tissue contacting the wall.

31. A system according to claim 30

wherein R_TISSUE is about 100 ohms.

32. A system according to claim 20 or 21 or 22

wherein the first electrically conductive element comprises members assembled within the interior area to form a support structure underlying the wall.

33. A system according to claim 32

wherein the support structure comprises an electrically conductive, resilient mesh structure.

34. A system according to claim 32

wherein the support structure comprises a skeleton of flexible, electrically conductive spline elements.

35. A system according to claim 32

wherein the support structure comprises an open cell foam structure coated with an electrically conductive material.

36. A system according to claim 32

wherein the support structure comprises a plastic material.

37. A system according to claim 32

wherein the support structure comprises elongated spline elements assembled in a circumferentially spaced relationship.

38. A system according to claim 20 or 21 or 22

and further including at least one temperature sensing element carried by the wall.

21. A system for ablating body tissue comprising

a catheter tube having a distal end,

a return electrode,

a fluid source of a medium containing ions,

a source of electrical energy,

an electrode on the distal end of the catheter tube comprising a nonporous wall having an exterior for contacting tissue and an interior peripherally surrounding an interior area, the exterior being essentially free of electrically conductive material, a first electrically conductive element disposed within the interior of the wall, the wall being adapted to assume an expanded geometry having a first maximum diameter and a collapsed geometry having a second maximum diameter less than the first maximum diameter, a lumen to convey the medium containing ions into the interior area, and a second electrically conductive element within the interior area free of physical contact with the first electrically conductive element, and

means for coupling the return electrode and the second electrically conductive element to the source of energy to enable ionic transport of electrical energy from the source through the medium to the first electrically conductive element for capacitive coupling to tissue to ablate tissue located between the return electrode and the electrode.

22. A system for ablating heart tissue comprising

a catheter tube having a distal end for deployment in a heart chamber,

a return electrode,

a fluid source of a medium containing ions,

a source of electrical energy,

an electrode on the distal end of the catheter tube comprising a nonporous wall having an exterior for contacting tissue and an interior peripherally surrounding an interior area, the exterior being essentially free of electrically conductive material, a first electrically conductive element disposed within the interior of the wall, the wall being adapted to assume an expanded geometry having a first maximum diameter and a collapsed geometry having a second maximum diameter less than the first maximum diameter, a lumen to convey the medium containing ions into the interior area, and a second electrically conductive element within the interior area free of physical contact with the first electrically conductive element, and

means for coupling the return electrode and the second electrically conductive element to the source of energy to enable ionic transport of electrical energy from the source through the medium to the first electrically conductive element for capacitive coupling to tissue to ablate heart tissue located between the return electrode and the electrode.

39. A method for heating body tissue comprising the steps of

providing a catheter tube having a distal end that carries an electrode comprising a nonporous wall having an exterior for contacting body tissue and an interior peripherally surrounding an interior area, the exterior being essentially free of electrically conductive material, a first electrically conductive element disposed within the interior of the wall, the wall being adapted to assume an expanded geometry having a first maximum diameter and a collapsed geometry having a second maximum diameter less than the first maximum diameter, a fluid source of a medium containing ions a lumen to convey the medium containing ions into the interior area, and a second electrically conductive element within the interior area free of physical contact with the first electrically conductive element,

electrically coupling a source of radio frequency energy to the second electrically conductive element and to a return electrode in contact with body tissue,

guiding the catheter tube into a body with the wall in the collapsed geometry,

causing the wall to assume the expanded geometry at least in part by conveying a medium containing ions into the interior area, and

ohmically heating body tissue by transmitting radio frequency energy to the second electrically conductive element for ionic transport through the medium to the wall for capacitive coupling to tissue located between the return electrode and the electrode.

42. A method according to claim 39 or 40 or 41

and further including the step of controlling the transmission of radio frequency energy, at least in part, by sensing temperature proximate to the wall.

40. A method for ablating body tissue comprising the steps of

providing a catheter tube having a distal end that carries an electrode comprising a nonporous wall having an exterior for contacting body tissue and an interior peripherally surrounding an interior area, the exterior being essentially free of electrically conductive material, a first electrically conductive element disposed within the interior of the wall, the wall being adapted to assume an expanded geometry having a first maximum diameter and a collapsed geometry having a second maximum diameter less than the first maximum diameter, a fluid source of a medium containing ions, a lumen to convey the medium containing ions into the interior area, and a second electrically conductive element within the interior area free of physical contact with the first electrically conductive element,

electrically coupling a source of radio frequency energy to the second electrically conductive element and to a return electrode in contact with body tissue,

guiding the catheter tube into a body with the wall in the collapsed geometry,

causing the wall to assume the expanded geometry at least in part by conveying a medium containing ions into the interior area, and

ohmically ablating body tissue by transmitting radio frequency energy to the second electrically conductive element for ionic transport through the medium to the wall for capacitive coupling to tissue located between the return electrode and the electrode.

41. A method for ablating heart tissue comprising the steps of

providing a catheter tube having a distal end that carries an electrode comprising a nonporous wall having an exterior for contacting heart tissue and an interior peripherally surrounding an interior area, the exterior being essentially free of electrically conductive material, a first electrically conductive element disposed within the interior of the wall, the wall being adapted to assume an expanded geometry having a first maximum diameter and a collapsed geometry having a second maximum diameter less than the first maximum diameter, a fluid source of a medium containing ions, a lumen to convey the medium containing ions into the interior area, and a second electrically conductive element within the interior area free of physical contact with the first electrically conductive element,

electrically coupling a source of radio frequency energy to the second electrically conductive element and to a return electrode in contact with body tissue,

guiding the catheter tube into a heart chamber with the wall in the collapsed geometry,

causing the wall to assume the expanded geometry at least in part by conveying a medium containing ions into the interior area, and

ohmically ablating heart tissue by transmitting radio frequency energy to the second electrically conductive element for ionic transport through the medium to the wall for capacitive coupling to tissue located between the return electrode and the electrode.