An implantable medical support frame (104) having a central longitudinally extending axis is expandable from a collapsed configuration having a first diameter to an expanded configuration having a second diameter. The frame also includes an anchoring mechanism with an elongate member (110). At least a portion of the elongate member is slidably disposed within a retaining structure when the frame is in the collapsed configuration. When the frame expands from the collapsed configuration to the expanded configuration, a portion of the elongate member is advanced out of the retaining structure such that the portion of the elongate member protrudes radially outward of the frame at an angle to the axis, thereby forming an anchor. A length of the protruding portion of the anchor increases as the frame expands from the collapsed configuration to the expanded configuration.