A bifurcated endovascular prosthesis that includes a tubular main body having a diameter, a proximal end, a distal end, an internal lumen extending from the proximal end to the distal end, an anterior side, and a posterior side. The anterior and posterior sides are opposite each other circumferentially around the internal lumen. The prosthesis also includes a first limb that extends from the distal end of the tubular main body along the anterior side of the main body. The first limb has a diameter less than the diameter of the tubular main body and having a proximal end and a distal end. The prosthesis also includes a fenestration adjacent to the proximal end of the first limb. The fenestration extends from the proximal end of the first limb to the posterior side of the tubular main body. The prosthesis also includes a second limb that extends within the internal lumen from the fenestration toward the proximal end of the tubular main body. The fenestration has a substantially diamond shape and a nonlinear profile, and the second limb extends into the lumen along the posterior side of the tubular main body.
