A method is disclosed for using tubular material to replace a semilunar heart valve (i.e., an aortic or pulmonary valve). To create such a replacement valve, the native valve cusps are removed from inside an aorta or pulmonary artery, and the inlet end of a tubular segment is sutured to the valve annulus. The outlet (distal) end of the tube is either “tacked” at three points distally, or sutured longitudinally along three lines; either method will allow the flaps of tissue between the suture lines to function as movable cusps. This approach generates flow patterns that reduce turbulence and closely duplicate the flow patterns of native semilunar valves. An article of manufacture is also disclosed, comprising a sterile biocompatible synthetic material which has been manufactured in tubular form, by methods such as extrusion or coating a cylindrical molding device, to avoid a need for a suture line or other seam to convert a flat sheet of material into a tubular shape. The synthetic tube is packaged within a sealed watertight enclosure that maintains sterility of the tube.