An apparatus, comprising: a prosthetic heart valve (100, 400) that includes an inner frame (150, 450) and an outer frame (120, 420) coupleable to the inner frame via at least one suture (102, 402), the inner frame (150, 450) and the outer frame (120, 420) can be moved between a first position relative to each other in which the outer frame (120, 420) is disposed substantially axially proximal of the inner frame (150, 450) and a second position relative to each other in which the inner frame (150, 450) is nested substantially within an interior portion of the outer frame (120, 420), the prosthetic valve (100, 400) movable between a first configuration for delivery into a heart of a patient and a second configuration when implanted in the heart, the prosthetic valve (100, 400) being in the first configuration when the inner frame (150, 450) and the outer frame (120, 420) are in the first position relative to each other, the prosthetic valve (100, 400) being in the second configuration when the inner frame (150, 450) and the outer frame (120, 420) are in the second position relative to each other, characterised in that the at least one suture (102, 402) is securely attached to the inner frame (150, 450) and extends through apertures in the outer frame (120, 420) to a location proximal to the outer frame (120, 420), the at least one suture (102, 402) includes a slip knot (104, 404) disposed proximal to the outer frame (120, 420) that can be moved relative to the at least one suture (102, 402) to secure the outer frame (120, 420) to the inner frame (150, 450) when the prosthetic heart valve (100, 400) is in the second configuration. a prosthetic heart valve (100, 400) that includes an inner frame (150, 450) and an outer frame (120, 420) coupleable to the inner frame via at least one suture (102, 402), the inner frame (150, 450) and the outer frame (120, 420) can be moved between a first position relative to each other in which the outer frame (120, 420) is disposed substantially axially proximal of the inner frame (150, 450) and a second position relative to each other in which the inner frame (150, 450) is nested substantially within an interior portion of the outer frame (120, 420), the prosthetic valve (100, 400) movable between a first configuration for delivery into a heart of a patient and a second configuration when implanted in the heart, the prosthetic valve (100, 400) being in the first configuration when the inner frame (150, 450) and the outer frame (120, 420) are in the first position relative to each other, the prosthetic valve (100, 400) being in the second configuration when the inner frame (150, 450) and the outer frame (120, 420) are in the second position relative to each other, characterised in that the at least one suture (102, 402) is securely attached to the inner frame (150, 450) and extends through apertures in the outer frame (120, 420) to a location proximal to the outer frame (120, 420), the at least one suture (102, 402) includes a slip knot (104, 404) disposed proximal to the outer frame (120, 420) that can be moved relative to the at least one suture (102, 402) to secure the outer frame (120, 420) to the inner frame (150, 450) when the prosthetic heart valve (100, 400) is in the second configuration.