Helical arm tie down

A stent graft comprising a tubular body of a biocompatible graft material having a proximal end, a distal end, a side wall and an ostium in the side wall of the tubular body between the proximal end and the distal end,

• the tubular body having a circumference, a tubular body surface, and a side arm extending from the ostium, the side arm comprising a transversely corrugated, unstented tube of graft material extending at least partially helically around and along the tubular body of the stent graft at least one-fourth the circumference of the tubular body to an open end,
• the side arm comprising a resilient reinforcing ring attached about and encircling its open end, where the resilient reinforcing ring is permanently attached to the tubular body with a tie down arrangement that passes through the graft material of the tubular body and through the side arm and engages the resilient reinforcing ring to permanently hold the open end of the side arm against the tubular body surface, wherein the side arm has a length extending from the ostium to its open end and comprises a line of radiopaque markers extending along substantially the length of the side arm from the ostium to the open end, and wherein the line of radiopaque markers comprises a helical line relative to the tubular body of the stent graft, and
• a temporary tie down arrangement for the side arm, separate from the first tie down arrangement, the temporary tie down arrangement comprising at least one elongate longitudinally extending wire extending proximally of the ostium end of the side arm to distally of the ostium of the side arm and holding flat the ostium end of the side arm during loading of the stent graft into a deployment device.