A leaflet support device, comprising: a frame comprising a first frame and a second frame, the frame defining a shape defined by a tubular member bisected by a flat ring at a base of the tubular member, wherein the first frame defines the tubular member, the base and a first frame central axis and the second frame defines the flat ring, and wherein the second frame is coupled to the first frame at the base and substantially perpendicular to and coaxial with the first frame central axis, the tubular member defining a tubular member central axis and having a decreasing taper from a first end to the base and defining a tubular member central opening at the base through which blood flows during use, wherein the tubular member is configured to conform to and be coupled with an atrial side of a heart adjacent to an atrioventricular valve, the flat ring defining a ring central axis having a second frame central opening through which blood flows during use, the flat ring being substantially perpendicular to and coaxial with the tubular member central axis, wherein the flat ring defines an inner portion that extends into the tubular member central opening and an outer portion that extends away from the tubular member central opening, the outer portion being configured to rest against a ventricular side of an annulus of the atrioventricular valve; and one or more support leaflets (200; 200a; 200b), each support leaflet (200; 200a; 200b) comprising a leaflet attachment region either coupled to the flat ring or coupled to the base adjacent the flat ring and a free edge (210; 210a; 210b) opposite the leaflet attachment region each support leaflet (200; 200a; 200b) being configured to pivot about a respective leaflet attachment region to move between an open and a closed position, wherein in the closed position the support leaflet (200; 200a; 200b) lies adjacent a ventricular side of the second frame, wherein each support leaflet (200; 200a; 200b) is configured to support at least a portion of an atrial-facing surface of an atrioventricular valve leaflet when in the closed position, wherein the inner portion of the second frame is configured to limit a degree of movement of at least one of the one or more support leaflets (200; 200a; 200b) when the one or more support leaflets (200; 200a; 200b) are moving from the open to the closed position, wherein each support leaflet (200; 200a; 200b) coapts against the ventricular side of the inner portion of the second frame, wherein each support leaflet (200; 200a; 200b) is configured such that the support leaflet free edge (210; 210a; 210b) moves correspondingly with an atrioventricular valve leaflet to the open position and moves correspondingly with the atrioventricular valve leaflet to the closed position during use. a frame comprising a first frame and a second frame, the frame defining a shape defined by a tubular member bisected by a flat ring at a base of the tubular member, wherein the first frame defines the tubular member, the base and a first frame central axis and the second frame defines the flat ring, and wherein the second frame is coupled to the first frame at the base and substantially perpendicular to and coaxial with the first frame central axis, the tubular member defining a tubular member central axis and having a decreasing taper from a first end to the base and defining a tubular member central opening at the base through which blood flows during use, wherein the tubular member is configured to conform to and be coupled with an atrial side of a heart adjacent to an atrioventricular valve, the flat ring defining a ring central axis having a second frame central opening through which blood flows during use, the flat ring being substantially perpendicular to and coaxial with the tubular member central axis, wherein the flat ring defines an inner portion that extends into the tubular member central opening and an outer portion that extends away from the tubular member central opening, the outer portion being configured to rest against a ventricular side of an annulus of the atrioventricular valve; and one or more support leaflets (200; 200a; 200b), each support leaflet (200; 200a; 200b) comprising a leaflet attachment region either coupled to the flat ring or coupled to the base adjacent the flat ring and a free edge (210; 210a; 210b) opposite the leaflet attachment region each support leaflet (200; 200a; 200b) being configured to pivot about a respective leaflet attachment region to move between an open and a closed position, wherein in the closed position the support leaflet (200; 200a; 200b) lies adjacent a ventricular side of the second frame, wherein each support leaflet (200; 200a; 200b) is configured to support at least a portion of an atrial-facing surface of an atrioventricular valve leaflet when in the closed position, wherein the inner portion of the second frame is configured to limit a degree of movement of at least one of the one or more support leaflets (200; 200a; 200b) when the one or more support leaflets (200; 200a; 200b) are moving from the open to the closed position, wherein each support leaflet (200; 200a; 200b) coapts against the ventricular side of the inner portion of the second frame, wherein each support leaflet (200; 200a; 200b) is configured such that the support leaflet free edge (210; 210a; 210b) moves correspondingly with an atrioventricular valve leaflet to the open position and moves correspondingly with the atrioventricular valve leaflet to the closed position during use.