Abstract: A stent assembly comprises a stent whose configuration can change between a transversely compressed state for delivery into a lumen in a human or animal body, and a relaxed state in which in use the stent contacts the lumen to support it. The stent is positioned in a delivery device and constrained by it in its transversely compressed state. The delivery device comprises a tubular member formed from a shape memory alloy and can be fitted to or within a catheter for delivery of the stent through a lumen.

Abstract: A stent for use in a lumen in a human or animal body, has a generally tubular body formed from a shape memory alloy which has been treated so that it exhibits enhanced elastic properties with a point of inflection in the stress-strain curve on loading, enabling the body to be deformed inwardly to a transversely compressed configuration for insertion into the lumen and then revert towards its initial configuration, into contact with and to support the lumen. The shape memory alloy comprises nickel, titanium and from about 3 at. % to about 20 at. %, based on the weight of the total weight of the alloy composition, of a ternary element selected from the group consisting of niobium, hafnium, tantalum, tungsten and gold. The ratio of the stress on loading to the stress on unloading at the respective inflection points on the loading and unloading curves is at least about 2.5:1, and the difference between the stresses on loading and unloading at the inflection points at least about 250 MPa.

Abstract: A composite stent device comprises a shape memory alloy stent sleeve which is treated so that it can exert an outward force on a lumen in which the stent device is to be deployed, and a restraint element which restricts the maximum transverse dimension to which the stent sleeve can expand outwardly. The restraint sleeve can minimize damage to a lumen by a stent located within it. It can be arranged to allow the stent device to be deformed in a bending mode, for example when the lumen in which the device is located is subjected to a transverse flattening deformation, relying on the enhanced elastic properties of the shape memory alloy stent sleeve to recover to the open, generally rounded configuration.