Side branch stent graft

A side arm stent graft comprising a main tube of a biocompatible material and a side arm tube comprising a of biocompatible material extending from the main tube at an angle thereto and attached thereto at a joined region by stitching, the joined region having a first end and a second end, and being in fluid communication therewith, wherein the side arm stent graft further comprises a triangular aperture in the main tube around the periphery of which the side arm tube is attached, the triangular aperture having a base at a proximal end and a pair of sides distal to the base, and an end of the side arm tube having a bevel to leave an end portion having a circumferential length equal to the length of the base of the triangular aperture and a length of the bevel equal to the length of the sides of the triangular aperture, whereby the side arm tube is stitched to the main tube around the periphery of the triangular aperture with the end portion abutting the base of the triangular aperture and the bevel abutting the sides of the triangular aperture, further comprising a plurality of self-expanding stents along the main tube, wherein a self-expanding stent of the plurality of self-expanding stents extends around both the main tube and the side arm tube at the joined region, wherein a circumference of the joined region of the main tube and side arm tube increases along the length of the stitches at the first end of the joined region from a circumference of the main tube to the sum of the circumferences of the main tube and the side arm tube at the second end of the joined region.