Circumferential ablation device assembly

• US 6,024,740 A
• Filed: 07/08/1997
• Issued: 02/15/2000
• Est. Priority Date: 07/08/1997
• Status: Expired due to Term

• Current Assignee: Emory University, Atrionix, Inc. (Johnson & Johnson), Regents of the University of California (University of California)
• Original Assignee: Emory University, Atrionix, Inc. (Johnson & Johnson), Regents of the University of California (University of California)
• Inventors: Lesh, Michael D., Langberg, Jonathan J., Peacock, James C. III, Ross, Michael Ronald
• Primary Examiner(s): MANUEL, GEORGE C
• Application Number:
  US08/889,798
• Time in Patent Office: 952 Days
• Field of Search: 600/373, 600/374, 600/375, 600/381, 606/32, 606/40, 606/41, 606/46, 606/47, 606/48, 606/34, 607/122, 601/2
• US Class Current: 606/34
• 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 18/1492 having a flexible, catheter-like structure, e.g. for heart ablation A61B18/1477 takes precedence
• CPC Class Codes: A61B 18/1815 using microwaves
• CPC Class Codes: A61B 2017/00243 cardiac
• CPC Class Codes: A61B 2017/22038 with a guide wire
• CPC Class Codes: A61B 2017/22054 with two balloons
• CPC Class Codes: A61B 2017/22067 Blocking; Occlusion A61B2017/22054 takes precedence
• CPC Class Codes: A61B 2018/00011 with fluids
• CPC Class Codes: A61B 2018/0016 Energy applicators arranged in a two- or three dimensional array
• CPC Class Codes: A61B 2018/00214 Expandable means emitting energy, e.g. by elements carried thereon
• CPC Class Codes: A61B 2018/00273 Anchoring means for temporary attachment of a device to tissue
• CPC Class Codes: A61B 2018/00285 Balloons
• CPC Class Codes: A61B 2018/00291 using suction
• CPC Class Codes: A61B 2018/00369 Heart valves
• CPC Class Codes: A61B 2018/00375 Ostium, e.g. ostium of pulmonary vein or artery
• CPC Class Codes: A61B 2018/00797 measured by multiple temperature sensors
• CPC Class Codes: A61B 2018/00815 measured by a thermistor
• CPC Class Codes: A61B 2018/00821 measured by a thermocouple
• CPC Class Codes: A61B 2018/00839 Bioelectrical parameters, e.g. ECG, EEG
• CPC Class Codes: A61B 2018/00898 Alarms or notifications created in response to an abnormal condition
• CPC Class Codes: A61B 2018/00994 : combining two or more different kinds of non-mechanical energy or combining one or more non-mechanical energies with ultrasound
• CPC Class Codes: A61B 2218/002 : Irrigation
• CPC Class Codes: A61N 7/02 : Localised ultrasound hyperthermia hyperthermia in general A61F7/00

Abstract

This invention is a circumferential ablation device assembly which is adapted to forming a circumferential conduction block in a pulmonary vein. The assembly includes a circumferential ablation element which is adapted to ablate a circumferential region of tissue along a pulmonary vein wall which circumscribes the pulmonary vein lumen, thereby transecting the electrical conductivity of the pulmonary vein against conduction along its longitudinal axis and into the left atrium. The circumferential ablation element includes an expandable member with a working length that is adjustable from a radially collapsed position to a radially expanded position. An equatorial band circumscribes the outer surface of the working length and is adapted to ablate tissue adjacent thereto when actuated by an ablation actuator. The equatorial band has a length relative to the longitudinal axis of the expandable member that is narrow relative to the working length, and is also substantially shorter than its circumference when the working length is in the radially expanded position. A pattern of insulators may be included over an ablation element which otherwise spans the working length in order to form the equatorial band described. The expandable member is also adapted to conform to the pulmonary vein in the region of its ostium, such as by providing a great deal of radial compliance or by providing a taper along the working length which has a distally reducing outer diameter. A linear ablation element is provided adjacent to the circumferential ablation element in a combination assembly which is adapted for use in a less-invasive "maze"-type procedure in the region of the pulmonary vein ostia in the left ventricle.

Claims

1. A tissue ablation device system that ablates a circumferential region of tissue at a location where a pulmonary vein extends from a posterior left atrial wall of a left atrium in a patient, comprising:

an elongate body with a proximal end portion, a distal end portion and a longitudinal axis;

an inflatable balloon located along the distal end portion and having a working length along the longitudinal axis which is adjustable between a radially collapsed position and a radially expanded position, the working length further being defined between first and second ends and having a first end portion, a second end portion, an intermediate portion positioned between the first and second end portions, and an expanded outer diameter when in the radially expanded position which is sufficient along the intermediate portion to engage the circumferential region of tissue, and

a circumferential ablation element having a circumferential band that is located along the distal end portion at a position relative to the longitudinal axis that generally coincides with the intermediate portion and that is substantially spaced from the first and second ends such that movement of the elongated body moves the inflatable balloon and the circumferential band together, the circumferential band also having a band width along the longitudinal axis which is shorter than the working length and being adapted to ablatively couple to a circumferential area surrounding only the intermediate portion such that tissue ablation principally occurs along the circumferential region of tissue when engaged by the intermediate portion and spaced from the first and second ends of the working length in the radially expanded position.

2. The system of claim 1, wherein the circumferential band further comprises an ablation electrode which is electrically coupled to a conductive lead and which is adapted to emit current into the circumferential region of tissue engaged by the intermediate portion in the radially expanded position when the conductive lead is also coupled to an ablation actuator which includes an electrical current source.

3. The system of claim 2, further comprising:

a return electrode adapted to be secured to and in electrical contact with the patient'"'"'s body and which is coupled to a ground lead;

an ablation actuator which includes a radio-frequency current source which is adapted to couple to both the ground lead and also to a conductive lead connected to the ablation electrode; and

wherein a radio-frequency ablation circuit is formed upon actuation and includes the ablation actuator, the conductive lead, the ablation electrode, the patient'"'"'s body, the return electrode, and the ground lead.

4. The system of claim 1, wherein the working length of the inflatable balloon when adjusted to the radially expanded position is adapted to engage a pulmonary vein ostium of the pulmonary vein.

5. The system of claim 4, wherein the working length of the inflatable balloon further comprises a proximal region and a distal region and has a shape when in the radially expanded position that includes a taper with a distally reducing outer diameter from the proximal region to the distal region.

6. The system of claim 5, wherein the intermediate portion overlaps at least in part with the proximal region and the circumferential band is located along the taper in the proximal region.

7. The system of claim 1, wherein the working length of the inflatable balloon is adjustable between a plurality of radially expanded positions having a range of expanded outer diameters at least along the intermediate portion;

and

the circumferential band is adapted to ablatively couple to the circumferential area and to ablate a continuous circumferential lesion pattern in tissue engaged by the intermediate region over the range of expanded outer diameters.

8. The system of claim 7, wherein the circumferential band further comprises a circumference and a secondary shape which defines an overall band length relative to the longitudinal axis such that the overall band length shortens as the circumference of the circumferential band increases when the working length is expanded between two of the plurality of radially expanded positions.

9. The system of claim 8, wherein the secondary shape is selected from the group of shapes consisting of a serpentine shape and a sawtooth shape.

10. The system of claim 7, wherein the circumferential band comprises a plurality of individual ablation element portions positioned in a circumferentially spaced arrangement about the longitudinal axis, each of said individual ablation element portions comprising a long axis and a short axis, the long axis having two opposite end portions, each of said individual ablation element portions also being positioned with its long axis skewed at an angle relative to the longitudinal axis, and each end portion of each of said individual ablation element portions being positioned to form a circumferential overlap region with another end portion of another adjacent individual ablation element portion;

and

whereby adjusting the working length between two radially expanded positions, the position of each individual ablation element portion is adjusted relative to each adjacent individual ablation element portion such that the circumferential overlap regions between adjacent individual ablation element portions are reduced although maintained.

11. The system of claim 7, wherein the inflatable balloon when adjusted to each of the radially expanded positions is adapted to engage each of a plurality of pulmonary vein ostia having different inner diameters.

12. The system of claim 11, wherein the inflatable balloon comprises a substantially compliant balloon material which is adapted to engage each of the plurality of pulmonary vein ostia when the inflatable balloon is expanded to a corresponding radially expanded position in a left atrium and advanced retrogradedly from the left atrium against the respective ostium.

13. The system of claim 12, wherein the substantially compliant balloon material is selected from the group of materials consisting of silicone, latex rubber, and polyvinyl chloride.

14. The system of claim 1, wherein the band width is less than two-thirds of the working length.

15. The system of claim 1, wherein the radially expanded position of the intermediate portion has a circumference, and the band width is less than two-thirds of the circumference.

16. The system of claim 1, further comprising:

a linear ablation member located at least in part along the distal end portion and which has an elongate ablation element length and a linear ablation element, said linear ablation member being adapted to form a continuous linear lesion in tissue adjacent to the linear ablation element when the linear ablation element is coupled to an ablation actuator.

17. The system of claim 16, wherein the linear ablation element further comprises an electrode which is coupled to an electrical conductor which has a proximal conductor end in the region of the proximal end portion that is adapted to couple to an electrical current source.

18. The system of claim 16, wherein the linear ablation element further comprises a plurality of spaced electrodes, each electrode being coupled to an electrical conductor which has a proximal conductor end in the region of the proximal end portion that is adapted to couple to an electrical current source.

19. The system of claim 16, wherein the linear ablation member further comprises first and second linear ablation member ends, the first linear ablation member end being located adjacent to the expandable member which forms at least in part a first anchor adapted to secure the first linear ablation member end near a pulmonary vein ostium of the pulmonary vein along the posterior left atrial wall;

and

a second anchor is coupled to the second linear ablation member end and is adapted to secure the second linear ablation member end to a second location along the posterior left atrial wall.

20. The system of claim 19, wherein each of the first and second anchors further comprises a guidewire tracking member which forms a bore having first and second guidewire ports and which is adapted to track over a guidewire which is slideably received into the bore through the first and second guidewire ports.

21. The system of claim 1, wherein a circumferential portion of the working length that is located along the intermediate portion is adapted to be energized by an energy source and thereby forms at least in part the circumferential band.

22. The system of claim 21, wherein the working length in the radially expanded position defines at least in part an interior chamber;

and

the circumferential ablation element further comprises an interior energy source located within the interior chamber, said interior energy source being adapted to couple energy to and thereby energize the circumferential portion.

23. The system of claim 1, wherein the working length further comprises an outer surface along the intermediate region;

and

the circumferential band further comprises at least a portion of an exterior energy source that circumscribes the outer surface of the working length.

24. The system of claim 23, wherein the exterior energy source comprises at least a portion of an ablation electrode assembly which is adapted to couple to an electrical current source.

25. The system of claim 24, wherein the ablation electrode assembly includes first and second electrode end portions with an intermediate electrode portion extending therebetween along the longitudinal axis;

and

an electrical insulator is disposed on an outer surface of each of the first and second electrode end portions, such that only the intermediate electrode portion is substantially uninsulated and electrically exposed to thereby form the circumferential band.

26. The system of claim 24, wherein the circumferential band has a shape with an overall length that extends along the intermediate portion and between the first and second end portions.

27. The system of claim 1, wherein the circumferential band is adapted to emit a circumferential pattern of energy that ablatively couples to the circumferential area surrounding the intermediate portion.

75. The system of claim 1, 28, 45, 56, 64, 51, or 70, wherein the ablation element further comprises an electrode ablation element.

76. The system of claim 1, 28, 45, 56, 64, 51, or 70, wherein the ablation element further comprises a microwave ablation element.

77. The system of claim 1, 28, 45, 56, 64, 51, or 70, wherein the ablation element further comprises a cryogenic ablation element.

78. The system of claim 1, 28, 45, 56, 64, 51, or 70, wherein the ablation element further comprises an ultrasonic ablation element.

79. The system of claim 1, 28, 45, 56, 64, 51, or 70, wherein the ablation element further comprises a light emitting element ablation element.

80. The system of claim 1, 28, 45, 56, 64, 51, or 70, wherein the ablation element further comprises a thermal conduction ablation ablation element.

81. The system of claim 1, 28, 45, 56, 64, 51, or 70, wherein the ablation element further comprises a porous membrane.

28. A tissue ablation device system for ablating multiple circumferential regions of tissue with different inner diameters and which are each located where a pulmonary vein extends from a posterior left atrial wall of a left atrium in a patient, comprising:

an elongate body with a proximal end portion and a distal end portion and a longitudinal axis;

an expandable member located along the distal end portion and having a working length along the longitudinal axis which is adjustable between a radially collapsed position and a plurality of radially expanded positions which correspond to a range of outer diameters wherein the working length is adapted to engage each of the multiple circumferential regions of tissue; and

a circumferential ablation element which is coupled to the distal end portion in a fixed position relative to the working length and is adapted in each of the radially expanded positions to ablatively couple to a circumferential area surrounding the working length and to ablate a substantially continuous, transmural circumferential pattern in each of the multiple circumferential regions of tissue, respectively, when engaged by the working length.

29. The system of claim 28, wherein the circumferential ablation element further comprises a circumferential band which circumscribes the working length with a circumference, a band width relative to the longitudinal axis, and a secondary shape relative to the longitudinal axis that defines an overall band length relative to the longitudinal axis, and the secondary shape is adapted such that the overall band length shortens as the circumference increases when the working length is expanded to between multiple ones of the plurality of radially expanded positions.

30. The system of claim 29, wherein the secondary shape is selected from the group of shapes consisting of a serpentine shape and a sawtooth shape.

31. The system of claim 28, wherein the circumferential ablation element further comprises a circumferential band having a plurality of individual ablation elements positioned along the working length in a circumferentially spaced pattern about the longitudinal axis, each said individual ablation element comprising a long axis and a short axis, the long axis having two opposite end portions, each said individual ablation element also being positioned with its long axis skewed at an angle relative to the longitudinal axis, and each end portion of each said individual ablation element being positioned to form a circumferential overlap region with another end portion of another adjacent individual ablation element;

and

whereby adjusting the working length between two of the radially expanded positions, the position of each individual ablation element is adjusted relative to each adjacent individual ablation element such that the circumferential overlap regions between adjacent individual ablation elements are reduced although maintained.

32. The system of claim 28, wherein the expandable member when adjusted to each of the radially expanded positions is adapted to engage each of a variety of pulmonary vein ostia having different inner diameters.

33. The system of claim 32, wherein the working length has a proximal region, a distal region, and a shape in at least one of the radially expanded positions which comprises a taper with a distally reducing outer diameter from the proximal region to the distal region.

34. The system of claim 33, wherein the circumferential area surrounds the taper along the proximal region.

35. The system of claim 32, further comprising:

a linear ablation member which is located at least in part along the distal end portion and which has an elongate ablation element length and a linear ablation element, and which is adapted to form a continuous linear lesion in tissue adjacent to the linear ablation element when the linear ablation element is coupled to and actuated by an ablation actuator.

36. The system of claim 35, wherein the linear ablation element further comprises an electrode which is coupled to an electrical conductor which has a proximal conductor end in the region of the proximal end portion that is adapted to couple to an electrical current source.

37. The system of claim 35, wherein the linear ablation element further comprises a plurality of spaced electrodes, each electrode being coupled to an electrical conductor which has a proximal conductor end in the region of the proximal end portion that is adapted to couple to an ablation actuator which is an electrical current source.

38. The system of claim 28, further comprising:

a linear ablation member which is located at least in part along the distal end portion and which has an elongate ablation element length and a linear ablation element, and which is adapted to form a continuous linear lesion in tissue adjacent to the linear ablation element when the linear ablation element is coupled to and actuated by an ablation actuator.

39. The system of claim 38, wherein the linear ablation element further comprises an electrode which is coupled to an electrical conductor which has a proximal conductor end in the region of the proximal end portion that is adapted to couple to an electrical current source.

40. The system of claim 38, wherein the linear ablation element further comprises a plurality of spaced electrodes, each electrode being coupled to an electrical conductor which has a proximal conductor end in the region of the proximal end portion that is adapted to couple to an ablation actuator which is an electrical current source.

41. The system of claim 38, wherein the linear ablation member further comprises first and second linear ablation member ends, the first linear ablation member end being located adjacent to the expandable member which forms at least in part a first anchor adapted to secure the first linear ablation member end near a pulmonary vein ostium of the pulmonary vein along the posterior left atrial wall;

and

a second anchor is coupled to the second linear ablation member end and is adapted to secure the second linear ablation member end to a second location along the posterior left atrial wall.

42. The system of claim 41, wherein each of the first and second anchors further comprises a guidewire tracking member which forms a bore having first and second guidewire ports and which is adapted track over a guidewire which is slideably received into the bore through the first and second guidewire ports.

43. The system of claim 28, wherein the expandable member comprises an inflatable balloon which is constructed of a substantially compliant material.

44. The system of claim 43, wherein the substantially compliant material is selected from the group of materials consisting of silicone, latex rubber, and polyvinyl chloride.

45. A tissue ablation device system that ablates a circumferential region of tissue at a location where a pulmonary vein extends from a posterior left atrial wall of a left atrium in a patient, comprising:

an elongate body with a proximal end portion and a distal end portion and a longitudinal axis;

an expandable member located along the distal end portion and having a working length with a longitudinal dimension defined between ends of the working length along the longitudinal axis and which is adjustable between a radially collapsed position and a radially expanded position with an expanded outer diameter that is larger than a radially collapsed diameter, the working length also being positionable within the pulmonary vein and being adapted to engage the circumferential region of tissue when in the radially expanded position; and

a circumferential ablation element which is coupled to the working length of the expandable member such that movement of the elongated body moves the expandable member and the circumferential ablation element together, the circumferential ablation element being substantially spaced from the ends of the working length and being adapted to ablate the circumferential region of tissue when the working length is engaged to the circumferential region of tissue in the radially expanded position and also when the ablation element is actuated.

46. The system of claim 45, wherein the working length of the expandable member has a shape when in the radially expanded position that includes a taper with a distally reducing outer diameter from a proximal region to a distal region.

47. The system of claim 45, further comprising:

a linear ablation member that is located at least in part along the distal end portion and which has an elongate ablation element length and a linear ablation element which is adapted to form a continuous linear lesion in tissue adjacent to the linear ablation element when the linear ablation element is coupled to and actuated by an ablation actuator.

48. The system of claim 47, wherein the linear ablation element further comprises an electrode which is coupled to an electrical conductor which has a proximal conductor end in the region of the proximal end portion that is adapted to couple to an electrical current source.

49. The system of claim 47, wherein the linear ablation element further comprises a plurality of spaced electrodes, each electrode being coupled to an electrical conductor which has a proximal conductor end in the region of the proximal end portion that is adapted to couple to an electrical current source.

50. The system of claim 45, wherein the diameter of the working length in the radially expanded position is larger than the longitudinal dimension of the working length.

51. A tissue ablation device system that ablates a circumferential region of tissue at a location where a pulmonary vein extends from a posterior left atrial wall of a left atrium in a patient, comprising:

an elongated body with a proximal end portion and a distal end portion and a longitudinal axis;

an expandable member located along the distal end portion and having a working length along the longitudinal axis which is adjustable between a radially collapsed position and a radially expanded position which has an outer diameter which is larger when in the radially expanded position than when in the radially collapsed position, the working length also being adapted to engage the pulmonary vein ostium when in the radially expanded position;

a circumferential ablation element which is coupled to the working length of the expandable member, which is adapted to couple to and ablate the circumferential region of tissue when the expandable member is engaged to the circumferential region of tissue in the radially expanded position;

a linear ablation member coupled to the distal end portion of the elongate member with first and second linear ablation element ends and a linear ablation element therebetween which is adapted to ablate a continuous linear lesion in tissue adjacent thereto when the linear ablation element is coupled to and actuated by an ablation actuator, the first linear ablation member end being coupled to the expandable member which forms at least in part a first anchor adapted to secure the first linear ablation member end within the pulmonary vein ostium; and

a second anchor coupled to the second linear ablation member end which is adapted to secure the second linear ablation member end to a second location along the left atrium wall.

68. The system of claim 51, wherein each of the first and second anchors further comprises a guidewire tracking member which forms a bore having first and second guidewire ports and which is adapted track over a guidewire which is slideably received into the bore through the first and second guidewire ports.

69. The system of claim 51, wherein the expandable member is adjustable to a plurality of radially expanded positions which correspond to a range of expanded outer diameters along the working length, wherein each radially expanded position the expandable member is adapted to engage a different circumferential region of tissue having a different inner diameter.

52. A tissue ablation device system for ablating a circumferential region of tissue at a location where a pulmonary vein extends from a posterior left atrial wall of a left atrium in a patient, comprising:

an elongated body with a proximal end portion, a distal end portion and a longitudinal axis;

an expandable member located along the distal end portion with a working length along the longitudinal axis which is adjustable between a radially collapsed position and a radially expanded position, the working length having a first portion, a second portion, and an intermediate portion between the first and second portions along the longitudinal axis, and the working length at least along the intermediate portion being further constructed to define an interior space when in the radially expanded position; and

a circumferential ablation element having a circumferential band which is comprised of a porous membrane and which circumscribes the interior space at a location along the intermediate portion of the working length of the expandable member, the circumferential band in the radially expanded position having a band width along the longitudinal axis which is shorter than the working length and also having an expanded outer diameter which is adapted to engage the circumferential region of tissue, the porous membrane having an inner surface which is adapted to fluidly couple to a pressurizeable source of electrically conductive fluid, and the porous membrane further being adapted to pass a volume of electrically conductive fluid from the inner surface, externally through the porous membrane, and into the circumferential region of tissue when engaged by the circumferential band in the radially expanded position, the circumferential ablation element further including an ablation electrode which is adapted to electrically couple to an electrical current source and also to the volume of electrically conductive fluid which passes through the porous membrane.

53. The system of claim 52, wherein the porous membrane is disposed substantially along the working length and includes first and second membrane end portions with a middle membrane portion extending therebetween along the longitudinal axis;

and

an insulator is located along each of the first and second membrane end portions and is adapted to block the passage of conductive fluid from the inner surface and through the porous membrane into surrounding tissue, such that only the middle membrane portion is uninsulated and is adapted to pass electrically conductive fluids from the inner surface and into tissue adjacent to the middle membrane portion, the middle membrane portion thereby forming at least in part the circumferential band.

54. The system of claim 52, further comprising:

a pressurizeable conductive fluid source which includes a fluid reservoir that contains an electrically conductive fluid, the pressurizeable conductive fluid source being adapted to fluidly couple to the inner surface and thereby force the electrically conductive fluid through the porous membrane and into the circumferential region of tissue;

a return electrode adapted to be secured to and in electrical contact with the patient'"'"'s body and which is coupled to a ground lead; and

an ablation actuator which is a radio-frequency current source and which is adapted to electrically couple to both the conductive fluid passing through the porous membrane and also to the ground lead;

wherein a radio-frequency ablation circuit is formed upon actuation of the ablation actuator, the radio-frequency ablation circuit including the radiofrequency current source, a volume of electrically conductive fluid flowing through the porous membrane into the circumferential region of tissue, the patient'"'"'s body, the return electrode, and the ground lead.

55. The system of claim 52, wherein the expandable member further comprises an outer surface along the working length;

and

the porous membrane is disposed around and circumscribes the working length such that a pressurizeable electrolyte fluid chamber is formed at least in part between the inner surface of the porous membrane and the outer surface of the expandable member, wherein the pressurizeable electrolytic fluid chamber is adapted to couple to a pressurizeable source of electrically conductive fluid.

56. A tissue ablation device system that ablates a circumferential region of tissue at a location where a pulmonary vein extends from a posterior left atrial wall of a left atrium in a patient, comprising:

an elongated body with a proximal end portion, a distal end portion and a longitudinal axis;

an expandable member located along the distal end portion with a working length along the longitudinal axis which is adjustable between a radially collapsed position and a radially expanded position; and

a circumferential ablation element having a circumferential band that is comprised of a thermal conductor and that is located along the distal end portion at a position relative to the longitudinal axis that generally coincides with the working length of the expandable member, the circumferential band further having a band width along the longitudinal axis which is shorter than the working length,

wherein the radially expanded position the working length at least at the location coinciding with the circumferential band has an outer diameter that is sufficient to engage the circumferential region of tissue, and wherein the circumferential band is adapted to emit a circumferential pattern of thermal energy into the circumferential region of tissue when the circumferential region of tissue is engaged by the working length in the radially expanded position and when the thermal conductor is coupled to and actuated by a thermal ablation actuator.

57. The system of claim 56, wherein the thermal conductor is positioned substantially along the working length of the expandable member and includes first and second conductor end portions with an intermediate conductor portion extending therebetween along the longitudinal axis;

and

a thermal insulator is disposed on each of the first and second conductor end portions, such that the intermediate conductor portion is substantially uninsulated and thermally exposed to thereby form the circumferential band.

58. The system of claim 56, wherein the thermal conductor further comprises an electrical conductor which is adapted to resistively heat and emit thermal energy when coupled to and actuated by an electrical current source.

59. The system of claim 56, wherein the thermal conductor is adapted to be conductively heated and thereby emit thermal energy when coupled to and actuated by a thermal energy source.

60. The system of claim 59, wherein the expandable member further comprises an inflatable balloon which forms a balloon chamber that is coupled to a fluid passageway which extends along the longitudinal axis of the elongate body and terminates in a proximal inflation port in the region of the proximal end portion of the elongate body, the proximal inflation port being adapted to couple to a pressurizeable fluid source;

and

the circumferential ablation element further comprises a heater element adapted to heat fluid within the balloon chamber, wherein the heated fluid in the balloon chamber heats the thermal conductor which in turn emits heat into the circumferential region of tissue engaged by the working length in the radially expanded position.

61. The system of claim 56, wherein a circumferential portion of the working length is thermally conductive and forms at least in part the circumferential band.

62. The system of claim 61, wherein the working length in the radially expanded position defines at least in part an interior space;

and

the circumferential ablation element further comprises an interior thermal energy source located within the interior space and which is adapted to couple thermal energy to and thereby heat the circumferential portion.

63. The system of claim 56, wherein the working length of the expandable member further comprises an outer surface;

and

the circumferential band comprises an exterior thermal conductor that circumscribes the outer surface of the working length.

64. A tissue ablation device system that ablates a circumferential region of tissue at a location where a pulmonary vein extends from a posterior left atrial wall of a left atrium in a patient, comprising:

an elongated body with a proximal end portion and a distal end portion and a longitudinal axis;

an inflatable balloon located along the distal end portion which is coupled to a fluid passageway that extends between the inflatable balloon and a proximal inflation port that is adapted to couple to a pressurizeable fluid source, the inflatable balloon also being comprised of a substantially compliant balloon material and having a working length along the longitudinal axis which is adjustable between a radially collapsed position and a radially expanded position which has an expanded outer diameter that is sufficient to engage the circumferential region of tissue; and

an ablation element coupled to the elongate body and adapted to couple to an ablation actuator, and also when actuated, to ablatively couple to a circumferential area surrounding the working length,

whereby adjusting the inflatable balloon to the radially expanded position in the left atrium and thereafter forcing the inflatable balloon retrogradedly against the pulmonary vein ostium, the working length is adapted to engage a pulmonary vein ostium of the pulmonary vein along the posterior left atrial wall such that the circumferential area is positioned along the circumferential region of tissue and wherein the ablation element is adapted to couple to and ablate the circumferential region of tissue.

65. The system of claim 64, wherein the substantially compliant balloon material is selected from the group of materials consisting of silicone, latex rubber, and polyvinyl chloride.

66. The system of claim 64, wherein:

the circumferential ablation element is coupled to a circumferential band that circumscribes the working length of the inflatable balloon in the radially expanded position, the circumferential band having a band width along the longitudinal axis which is shorter than the working length, and the circumferential ablation element being adapted to ablate the circumferential region of tissue when the circumferential band is engaged to the circumferential region of tissue and the circumferential ablation element is coupled to and actuated by an ablation actuator.

67. The system of claim 64, wherein:

the working length is adjustable to a plurality of radially expanded positions which correspond to a range of expanded outer diameters along the working length, the range of expanded outer diameters being larger than a collapsed outer diameter of the inflatable balloon when in the radially collapsed position; and

whereby adjusting the inflatable balloon to multiple ones of the plurality of radially expanded positions within the left atrium and thereafter advancing the inflatable balloon retrogradedly against the pulmonary vein ostium, the inflatable balloon is adapted to engage each of a plurality of such circumferential regions of tissue having different inner diameters.

70. A tissue ablation device assembly that ablates a circumferential region of tissue at a location where a pulmonary vein extends from a posterior left atrial wall of a left atrium in a patient, comprising:

an elongate body with a proximal end portion, a distal end portion and a longitudinal axis; and

a circumferential ablation member with an inflatable balloon located along the distal end portion and having a working length along the longitudinal axis which is adjustable between a radially collapsed position and a radially expanded position, the working length having an expanded outer diameter in the radially expanded position that is larger than when in the radially collapsed position and that is sufficient to engage the circumferential region of tissue, and

a circumferential ablation element having a single circumferential band also located along the distal end portion at a position relative to the longitudinal axis generally coinciding with the working length of the inflatable balloon such that movement of the elongate body moves the inflatable balloon and the circumferential ablation element together, the circumferential band being adapted to couple to and be actuated by an ablation actuator such that the circumferential ablation element ablatively couples to only a circumferential area that surrounds the circumferential bond wherein the circumferential ablation element is adapted to ablate only the circumferential region of tissue in a circumferential pattern when the working length is engaged to the circumferential region of tissue in the radially expanded position.

71. The system of claim 70, wherein a circumferential portion of the working length is adapted to be energized by an energy source to thereby form at least in part the circumferential band.

72. The system of claim 71, wherein the circumferential portion comprises a porous membrane.

73. The system of claim 71, wherein the working length in the radially expanded position defines at least in part an interior chamber;

and

the circumferential ablation element further comprises an interior energy source located within the interior chamber and which is adapted to couple energy to and thereby energize the circumferential portion.

74. The system of claim 70, wherein the working length further comprises an outer surface;

and

the circumferential band further comprises an exterior energy source that circumscribes the outer surface of the working length.