An endovascular stent-graft is provided that includes a generally tubular body, which (a) is configured to assume a radially-compressed delivery state and at least first and second radially-expanded deployment states, (b) is shaped so as to define a stepwise expanding portion, and (c) comprises a stent member. The stent member includes a plurality of self-expandable flexible structural stent elements, and at least one circumferential expansion element. The stent member is configured such that application of a force thereto, which is insufficient to cause plastic deformation of the self-expandable flexible structural stent elements and is sufficient to cause plastic deformation of the circumferential expansion element, causes an increase in a circumferential length of the circumferential expansion element, thereby transitioning the tubular body from the first radially-expanded deployment state to the second radially-expanded deployment state, thereby increasing a greatest internal perimeter of the expanding portion.
