A system for replacing a native heart valve with an invertible device is disclosed. The system comprises a delivery catheter, a pusher catheter slidably disposed within said delivery catheter, and a positioning mechanism comprising at least one tether connected to a middle region of an invertible device and releasably connecting a distal portion of said invertible device to said delivery catheter. During advancement of said invertible device out of said delivery catheter, the positioning mechanism initiates inversion of a proximal portion of said invertible device into an interior lumen of said distal portion of said invertible device by preventing further advancement of a distal portion of said invertible device.
