The present invention relates to medical devices and in particular to frameless grafting prostheses and methods of making and using such devices. The pumping chamber has a blood inlet and a tangential blood outlet. The vending service unit includes removable concession modules that a vendor can easily and quickly replace andor interchange. The lamp bulbs for the discharge lamps of the invention may include a melted-in molybdenum electrode andor an electrode feed or they may be free of any internal electrodes.