A method is disclosed for performing a medical procedure on a patient with two blood vessels, including a first lumen and a second lumen. The method involves making an incision in the skin to access the first and second locations of the blood vessels, puncturing the blood vessels at these locations, and inserting stent-grafts into the lumens. The stent-grafts include branching vascular grafts that are expanded to contact the inner surfaces of the lumens. The first and second vascular grafts are then connected to each other, providing fluid communication between the blood vessels. The incision is then closed, leaving the stent-grafts beneath the patient's skin. The method may be used for bypass procedures or arteriovenous grafts, among others.

A method of positioning a main stent at a vessel bifurcation includes positioning a main guidewire in the main vessel; and advancing a stent delivery system to a position proximate the bifurcation. The stent delivery system includes a catheter with a flexible side sheath attached thereto and a main stent positioned over the catheter. The flexible side sheath is positioned to pass through the side opening in the main stent. The method also includes advancing a branch guidewire through the flexible side sheath and into the branch vessel; and subsequently, advancing the catheter over the main guidewire while advancing the flexible side sheath over the branch guidewire while viewing relative movement of a marker positioned on the flexible side sheath with respect to at least one marker positioned on the catheter.