Abstract: Device comprising a helically shaped spiral spring and means for bringing the spring to expand from a first state of a certain diameter to a second state of larger diameter and vice versa, characterized thereby that said means are arranged to rotate the ends of the spring relative to each other with maintained length of the spring so that the transition from said first state to said second state takes place by reducing the number of spring turns within said length and the corresponding increase of the pitch of the spring, or to supply to a given length of the spring further spring material at at least one end of the said length of the spring so that the transition from said first state to said second state takes place independent of pitch and number of spring turns within the said length; and a method for transluminal implantation of an intravascular prosthesis using the said device.