A prosthetic heart valve (10; 100; 400; 600) comprising: a frame (12; 102) comprising a plurality struts (22; 110) and having an inflow end, an outflow end, and a longitudinal axis extending from the inflow end to the outflow end, wherein the struts (22; 110) are pivotably coupled together such that the frame (12; 102) can pivot between one or more radially compressed states and one or more radially expanded states; a valve structure disposed within the frame (12; 102), wherein the valve structure comprises a plurality of leaflets configured to allow blood flow through the valve structure from the inflow end of the frame (12; 102) to the outflow end of the frame (12; 102) and to restrict blood flow through the valve structure from the outflow end of the frame (12; 102) to the inflow end of the frame (12; 102); and an actuator (16; 104; 404; 604) coupled to the frame (12; 102) and configured to move the frame (12; 102) between the one or more radially compressed states and the one or more radially expanded states, wherein the actuator (16; 104; 404; 604) comprises a first portion (128; 414), a second portion (130; 416), a first lumen (124; 423), a second lumen (126; 421), a locking member (118; 418), and a locking element (120; 420), wherein the first lumen (124; 423) and the second lumen (126; 421) extend axially through the first portion (128; 414) and the second portion (130; 416) in a direction parallel to the longitudinal axis of the frame (12; 102), wherein the first lumen (124; 423) and the second lumen (126; 421) are spaced apart from each other and are parallel to each other, wherein the locking member (118; 418) is disposed in the first lumen (124; 423), is fixedly coupled to the first portion (128; 414), and is axially movable relative to a second portion (130; 416), wherein the second lumen (126; 421) is configured to receive an actuation shaft (222; 810) of a delivery apparatus (200; 800), characterised in that the actuation shaft (222; 810) can be releasably coupled to the first portion (128; 414) and can move axially relative to the second portion (130; 416), and thereby can move the frame (12; 102) between the one or more radially compressed states and the one or more radially expanded states, and in that the locking element (120; 420) is adjustably coupled to the locking member (118; 418) and configured to restrict relative axial movement between the locking member (118; 418) and the second portion (130; 416), and thereby lock the frame (12; 102) in the one or more radially compressed states or the one or more radially expanded states. a frame (12; 102) comprising a plurality struts (22; 110) and having an inflow end, an outflow end, and a longitudinal axis extending from the inflow end to the outflow end, wherein the struts (22; 110) are pivotably coupled together such that the frame (12; 102) can pivot between one or more radially compressed states and one or more radially expanded states; a valve structure disposed within the frame (12; 102), wherein the valve structure comprises a plurality of leaflets configured to allow blood flow through the valve structure from the inflow end of the frame (12; 102) to the outflow end of the frame (12; 102) and to restrict blood flow through the valve structure from the outflow end of the frame (12; 102) to the inflow end of the frame (12; 102); and an actuator (16; 104; 404; 604) coupled to the frame (12; 102) and configured to move the frame (12; 102) between the one or more radially compressed states and the one or more radially expanded states, wherein the actuator (16; 104; 404; 604) comprises a first portion (128; 414), a second portion (130; 416), a first lumen (124; 423), a second lumen (126; 421), a locking member (118; 418), and a locking element (120; 420), wherein the first lumen (124; 423) and the second lumen (126; 421) extend axially through the first portion (128; 414) and the second portion (130; 416) in a direction parallel to the longitudinal axis of the frame (12; 102), wherein the first lumen (124; 423) and the second lumen (126; 421) are spaced apart from each other and are parallel to each other, wherein the locking member (118; 418) is disposed in the first lumen (124; 423), is fixedly coupled to the first portion (128; 414), and is axially movable relative to a second portion (130; 416), wherein the second lumen (126; 421) is configured to receive an actuation shaft (222; 810) of a delivery apparatus (200; 800), characterised in that the actuation shaft (222; 810) can be releasably coupled to the first portion (128; 414) and can move axially relative to the second portion (130; 416), and thereby can move the frame (12; 102) between the one or more radially compressed states and the one or more radially expanded states, and in that the locking element (120; 420) is adjustably coupled to the locking member (118; 418) and configured to restrict relative axial movement between the locking member (118; 418) and the second portion (130; 416), and thereby lock the frame (12; 102) in the one or more radially compressed states or the one or more radially expanded states.