Abstract: A tubular vascular graft made of synthetic or natural material. In one embodiment of this invention the effective lumen of the vascular graft is controlled by providing a fenestrated diaphragm within the tubular graft, the periphery of which diaphragm is in engagement with the inner wall of the tubular graft. The diaphragm is made weak on at least two radial lines extending from the inside surface of the tubular graft to the edge of the diaphragm's central orifice. The effective orifice of the tubular graft is that of the diaphragm's central orifice when the diaphragm is intact, but is enlarged to be that of the graft's lumen when the diaphragm is ruptured at its weak radial lines, such as by using a balloon dilatation catheter. In a second version the tubular graft has a second wall along a portion of its length. The second inner wall bulges inwardly from the inner surface of the tubular graft with a saline solution filling the space between the wall and forming the bulge.