A prosthetic valve, comprising: a frame having an inflow end and an outflow end, wherein the frame is movable between a radially compressed and a radially expanded state; at least one expansion and locking mechanism, comprising: a guide member, coupled to the frame at a first location, and comprising: a guide member first surface, a guide member second surface, and two guide member through-holes (130a, 130b) extending between the guide member first surface and the guide member second surface; a base member, coupled to the frame at a second location spaced apart from the first location, and comprising: a base member first surface, a base member second surface, and two base member through-holes (140a, 140b) extending between the base member first surface and the base member second surface; and a wire comprising: a wire base end portion looped over the base member second surface, and two wire axial portions extending from the base member second surface, through the base member through-holes, toward and through the guide member through-holes; wherein movement of the base member in a first direction, relative to the guide member, causes the frame to foreshorten axially and expand radially; wherein each wire axial portion defines an axial lock portion at the region that extends beyond the guide member first surface; and wherein the axial lock portions are configured to form together a twist disposed over the guide member first surface when they are intertwined together, such that when the twist is formed, it is configured to prevent, along with the wire base end portion, recompression of the frame. a frame having an inflow end and an outflow end, wherein the frame is movable between a radially compressed and a radially expanded state; at least one expansion and locking mechanism, comprising: a guide member, coupled to the frame at a first location, and comprising: a guide member first surface, a guide member second surface, and two guide member through-holes (130a, 130b) extending between the guide member first surface and the guide member second surface; a base member, coupled to the frame at a second location spaced apart from the first location, and comprising: a base member first surface, a base member second surface, and two base member through-holes (140a, 140b) extending between the base member first surface and the base member second surface; and a wire comprising: a wire base end portion looped over the base member second surface, and two wire axial portions extending from the base member second surface, through the base member through-holes, toward and through the guide member through-holes; a guide member, coupled to the frame at a first location, and comprising: a guide member first surface, a guide member second surface, and two guide member through-holes (130a, 130b) extending between the guide member first surface and the guide member second surface; a base member, coupled to the frame at a second location spaced apart from the first location, and comprising: a base member first surface, a base member second surface, and two base member through-holes (140a, 140b) extending between the base member first surface and the base member second surface; and a wire comprising: a wire base end portion looped over the base member second surface, and two wire axial portions extending from the base member second surface, through the base member through-holes, toward and through the guide member through-holes; wherein movement of the base member in a first direction, relative to the guide member, causes the frame to foreshorten axially and expand radially; wherein each wire axial portion defines an axial lock portion at the region that extends beyond the guide member first surface; and wherein the axial lock portions are configured to form together a twist disposed over the guide member first surface when they are intertwined together, such that when the twist is formed, it is configured to prevent, along with the wire base end portion, recompression of the frame.