An artificial valve for implantation in a mammal body, in or adjacent to a mammal blood vessel, the artificial valve comprising a casing and a closing mechanism, with at least part of said closing mechanism being a first moving part adapted to make movements relative to said casing . The movements are movements to assume a fully open and a fully closed position for opening and closing, respectively, the blood flow through said blood vessel, as well as at least one position in between said fully open and fully closed positions. The first moving part is adapted to receive energy for at least one of its movements at least in part from an energy device which is also comprised in the artificial valve and arranged to be placed external to said blood vessel.
