Intravascular electrodes and anchoring devices for transvascular stimulation

1. A method of positioning an electrode array at an optimal stimulation site within a blood vessel, comprising: providing an expandable anchor having a first portion, a second portion, and a plurality of electrodes on the first portion, each of the first and second portions having a compressed position and an expanded position; with the first and second portions in the compressed position, positioning the anchor within a blood vessel; at a first location within the blood vessel, maintaining the second portion of the anchor in the compressed position while expanding the first portion to the expanded position, wherein expanding the first portion biases the electrodes in contact with walls of the blood vessel; performing a mapping procedure using the electrodes at the first location; after performing the mapping procedure, repositioning the anchor to place the electrodes at a second location different from the first location, wherein repositioning the anchor includes placing the electrodes into contact with the walls of the blood vessel at the second location while maintaining the second portion in the compressed position; performing a mapping procedure using the electrodes at the second location; and after performing a mapping procedure at the second location, expanding the second portion into contact with the walls of the blood vessel to chronically retain the electrodes at the second location.

2. The method of claim 1 , wherein repositioning the anchor includes moving the first portion of the anchor to the compressed position, moving the anchor to the second location, and then moving the first portion of the anchor to the expanded position.

3. The method of claim 1 , wherein the first portion of the anchor in the expanded position imparts first radial expansion forces against the blood vessel wall, wherein the second portion of the anchor in the expanded position imparts second radial expansion forces against the blood vessel wall, and wherein the second radial expansion forces are greater than the first radial expansion forces.

4. The method of claim 3 , wherein moving the second portion of the anchor to the expanded position distends the blood vessel walls in a radially outward direction, and wherein moving the first portion of the anchor to the expanded position does not distend the blood vessel walls in a radially outward direction.

5. The method of claim 1 , wherein expanding the first portion of the anchor while maintaining the second portion in the compressed position comprises releasing the first portion of the anchor from a sheath while maintaining the second portion of the anchor in a compressed position within the sheath, and wherein expanding the second portion of the anchor comprises releasing the second portion of the anchor from the sheath.

6. The method of claim 1 wherein expanding the second portion of the anchor comprises expanding the second portion without displacing the electrodes from their electrode locations.

7. The method of claim 2 , wherein expanding the first portion of the anchor while maintaining the second portion in the compressed position comprises releasing the first portion of the anchor from a sheath while maintaining the second portion of the anchor in a compressed position within the sheath, wherein repositioning the anchor includes positioning the first portion in a compressed position within the sheath, and wherein expanding the second portion of the anchor comprises releasing the second portion of the anchor from the sheath.

8. A method of anchoring an electrode array within a blood vessel, comprising the steps of:

providing an implant comprising an anchor, a lead extending from the anchor and having at least one conductor extending therethrough, and a flex circuit coupled to the anchor, the flex circuit comprising a flexible insulative substrate, a plurality of electrodes carried by the substrate, and a plurality of conductive traces carried by the substrate, each trace electrically coupled to an electrode and a conductor; with the anchor in a radially compressed position, percutaneously introducing the implant into a patient's vasculature; positioning the implant at a target site in a blood vessel; causing the anchor to expand at the target site to a radially expanded position, thereby placing the electrodes into contact with a wall of the blood vessel; after causing the anchor to expand: performing a mapping procedure at the target site; and positioning a second anchor in a radially compressed position within a lumen of the anchor; and expanding the second anchor to a radially expanded position to chronically retain the electrodes in contact with the wall of the blood vessel.

9. The method of claim 8 , wherein performing a mapping procedure at the target site includes performing mapping procedures with the electrodes at one or more sites within the blood vessel, and selecting one of said sites as the target site.

10. The method of claim 8 , wherein expanding the second anchor to the radially expanded position chronically retains the first anchor against the blood vessel wall.

11. The method of claim 8 , further including:

prior to positioning the implant at the target site, using a member detachably coupled to the anchor to position the implant at a first site in the blood vessel;

performing a mapping procedure at the first site;

manipulating the member to move the implant from the first site to a second site;

wherein performing the mapping procedure at the target site comprises performing mapping at the second site and determining the second site to be the target site; and

wherein the method further includes, with the anchor at the target site, detaching the member from the anchor.