A tubular graft/stent comprises a tubular sheath having at intervals along
its length a plurality of ring-like rigid members, which are attached to
the sheath around their respective circumferences and are made of a shape
memory material, so that when the members change shape the sheath adopts a
new cross section in conformity with the members along the sheath's whole
length. The members may be discontinuous to allow the adoption of a
contracted shape in the martensitic phase and an expanded shape in the
austenitic phase. A graft may also have a branched side tube which can be
inverted so as to be housed within the sheath.
