the left atrium 32 in the right superior pulmonary vein 34 a the right inferior pulmonary vein 34 b the left superior pulmonary vein 34 c the left inferior pulmonary vein 34 d and or in the wall of the left atrium 32 preferably the valve 30 described above is located to affect the flow and pressure of blood between the pulmonary veins 34 a d and the left atrium 32 or a portion of the left atrium 32 and to lessen the symptoms of mitral regurgitation from a dysfunctional mitral valve 36 including elevations and fluctuations in the pulmonary circulation the device 30 may be viewed as a one way valve limiting or restricting retrograde flow into the pulmonary circulation having a substantial fatigue life to withstand cyclical operation for a given period of implantation duration will be a factor in selection of both materials and construction this may include heat treatments to certain portions or all components of the device 30 and analysis of construction and manufacturing techniques to optimize device 30 life additionally a coating may be required to maintain patency of the device 30 during normal operation this may be a surface modification or treatment a coating added to the device 30 such as heparin or and albumin layer the valve could be a valve of any design including bioprosthetic mechanical or tissue valves examples of commonly used prosthetic valves include a ball valve 40 illustrated in fig9 a such as a starr edwards a single leaflet valve 50 illustrated in fig9 b such as a bjork shiley valve a bileaflet or bi disk valve 60 illustrated in fig9 c or an artificial tricuspid valve such.