Ablation cap

1. An ablation cap comprising:

a tubular body having a proximal portion, a distal portion, a lumen extending therethrough;

a cover portion covering a portion of the tubular body, the portion having a region at least partially spaced apart from the tubular body;

an electrode portion movably positionable relative to the cover portion, the electrode portion having a covered position wherein the electrode portion is positioned within the cover portion; and an exposed position wherein the electrode portion is distally movable relative to the cover portion and is exposed relative to the cover portion, the electrode portion comprising a plurality of electrodes; and

a stop to stop the electrode portion at a maximum extension in the exposed position;

wherein the proximal portion of the body is sized and shaped to fit on a distal end of an endoscope and the distal portion of the body extends distal to the distal end of the endoscope.

2. The ablation cap of claim 1 , wherein the cover portion is fixed in position on the proximal portion of the tubular body and includes a recess formed between the cover portion and the tubular body.

3. The ablation cap of claim 2 , further comprising a drive catheter operably connected to the electrode portion for moving the electrode portion to the covered and exposed positions.

4. The ablation cap of claim 1 , wherein the cover portion is movable relative to the tubular body.

5. The ablation cap of claim 1 , wherein the electrode portion is distally extendable so that a distal end of the electrode portion does not extend beyond a distal end of the distal portion of the body.

6. The ablation cap of claim 1 , wherein the plurality of electrodes are bipolar electrodes.

7. The ablation cap of claim 1 , wherein the tubular body comprises a transparent material, a translucent material or a magnifying material.

8. The ablation cap of claim 1 , wherein the electrode portion comprises a beveled edge extending axially away from the cap to scrape tissue.

9. The ablation cap of claim 1 , wherein the cap comprises a plurality of demarcations to indicate the position of the electrode portion relative to the cover.

10. The ablation cap of claim 1 , wherein the electrode portion further comprises separate areas, each separate area comprising an electrode, each electrode being separately energizable.

11. The ablation cap of claim 1 , wherein the electrode portion, in the covered position, is positioned entirely within the cover portion.

12. The ablation cap of claim 1 , wherein the distal portion of the tubular body is cylindrical so that the electrode portion is at least partially supported by the tubular body in the exposed position.

13. An ablation cap comprising:

a tubular body having a proximal portion, a distal portion, a lumen extending therethrough;

a cover portion covering a portion of the tubular body, the covering portion having a region at least partially spaced apart from the tubular body;

an electrode portion movably positionable relative to the cover portion, the electrode portion having a covered position wherein the electrode portion is positioned within the cover portion; and an exposed position wherein the electrode portion is distally movable relative to the cover portion and is exposed relative to the cover portion; and

a stop to stop the electrode portion at a maximum extension in the exposed position;

wherein the proximal portion of the body is sized and shaped to fit on a distal end of an endoscope and the distal portion of the body extends distal to the distal end of the endoscope; and

wherein the electrode portion is movably positionable into and out of view through the endoscope.

14. The ablation cap of claim 13 , wherein the cap further comprises a plurality of demarcations to indicate the position of the electrode portion relative to the cover.

15. The ablation cap of claim 13 , wherein the electrode portion is distally extendable and energizable when the electrode portion is extended less than 100%.

16. The ablation cap of claim 13 , wherein a wire connects the electrode portion to an energy source and the wire extends external to the endoscope.

17. A method of delivering energy to a tissue site within a patient's lumen, the method comprising:

positioning an ablation cap within a patient's lumen, the ablation cap positioned on a distal end of an endoscope, the ablation cap comprising:

a tubular body having a proximal portion, a distal portion, a lumen extending therethrough;

a cover portion covering a portion of the tubular body, the covering portion having a region at least partially spaced apart from the tubular body; and

an electrode portion movably positionable relative to the cover portion, the electrode portion comprising a plurality of electrodes;

moving the electrode portion relative to the cover portion to an exposed position to expose the electrode portion, controlling the amount of extension and providing a stop to stop the electrode portion at a maximum extension;

contacting the tissue with the electrode portion;

supplying energy to the plurality of electrodes from an energy source; and

ablating the tissue.

18. The method of claim 17 , further comprising moving the electrode portion relative to the cover portion to return the electrode portion to a covered position and repositioning the ablation cap at a second tissue site to be treated.

19. The method of claim 17 , further comprising scraping the tissue to remove a coagulum.

20. The method of claim 17 , comprising viewing the tissue through a magnifying portion of the tubular body.