Abstract: The invention discloses an artificial valve (10, 20) for implantation in a mammal aorta or heart as an auxiliary aortic valve in addition to an aortic valve. The artificial valve (10, 20) comprises at least a first (12,17) moving part adapted to be able to move to assume an open and a closed position for opening and closing, respectively, of the blood flow through a blood vessel. The artificial valve (10, 20) also comprises a casing (14, 24), and said at least one first (12,17) moving part is movably attached to said casing (14, 24). The artificial valve (10, 20) is adapted to let the at least one moving part initiate its movement to the open position at a level of blood pressure on a blood supplying side of the valve which is at least 5 mm Hg higher than the mammal's diastolic aortic blood pressure on the other side of the valve.