An endolumenal device (1) for delivering and deploying an endolumenal expandable prosthesis (6) at a bifurcation provided with a main conduit and at least a secondary conduit, comprises an elongated body (2) having a proximal end portion (4) and a distal end portion (3); the distal end portion (3) comprising expansion means (5) having a longitudinally extended active portion removably engageable with the prosthesis (6). Said active portion of the expansion means is longitudinally associated to the body in order to expand said prosthesis eccentrically from one side with respect to the body, in order to leave free from said expanded active portion the other side of the body. The device further is provided with guidewire tracking means (11).