An anchor anchors a therapeutic device having an elongated body within a body lumen. The anchor includes a fixation member carried on the device which is adjustable from a first configuration that permits placement of the device in the body lumen to a second configuration that anchors the device within the body lumen. The anchor further includes a lock that locks the fixation member in the second configuration. The fixation member may be locked in any one of a plurality of intermediate points between the first configuration and a maximum second configuration.