Patent ID: 8090449

Claim:
An implantable medical device for providing therapy to a body comprising: an elongate central portion; at least one expansion mechanism having a tip, the expansion mechanism depending from the central portion and being adapted to assume a range of positions, including a compact position, in which the tip is disposed in close proximity to the central portion, and an extended position, in which the tip is disposed at a location distal from the central portion; at least one therapy element disposed on the expansion mechanism for delivering therapy to the body; a linkage assembly for position adjustment of the expansion mechanism in situ, the linkage assembly comprising; a first, a second, a third, and a fourth strut each having a first end, a second end, and a center between the respective first and second ends; the first strut and second struts pivotally linked to one another at their respective first ends at a first point; the third strut and the fourth struts pivotally linked to one another at their respective first ends at a second point; wherein the second end of the third strut is pivotally connected to the center of the first strut; and the second end of the fourth strut is pivotally connected to the center of the second strut; wherein the expansion mechanism is adapted to contract when the first point and the second point are moved away from each other, and expand when the first point and the second point are moved towards each other.