Ends of an outer spiral and an inner spiral of similar dimensions but wound in opposite directions are joined to form a double spiral stent which may be covered to make it a stent graft. The dimensions are related by the formula of C=(Lw−Ls)/N where C is circumference of the spiral, Lw the length of the wire, N the number of turns and Ls the length of the spiral. Thus when length of spiral (Ls) is increased and decreased by compression and stretching, circumference (C) inversely varies with Ls, as N and Lw do not change. Ls and thus C are controlled by a control wire in a control tube attached to the ends of the double spiral being changed either by screwing male threads on the control wire into and out of female threads in the control tube.
