The present invention provides a catheter apparatus, an introducer system, and a methodology for creating a vascular bypass on-demand between an unobstructed blood vessel such as the aorta and an obstructed blood vessel such as an obstructed coronary artery in-vivo using a previously excised vascular segment as a shunt. The invention allows the placement and creation of single or multiple vascular grafts without use of a heart-lung machine and without need for stopping the heart of the patient during the coronary artery bypass surgery.