A pre-tied knot is used in conjunction with a vascular closure device to approximate tissue surrounding an opening in a corporeal vessel. The pre-tied knot is positioned on a proximal end of the suture such that a distal end of the suture can be inserted through the pre-tied knot to complete the knot. A typical medical procedure as contemplated by the present invention is performed through a sheath inserted through an opening in the vessel wall to access the inside of the vessel. The device used to perform the medical procedure is then removed from the sheath and a vascular closure device is inserted through the sheath to position a suture across the vessel opening. The pre-tied knot assists in approximating tissue surrounding the vessel opening.