A medical device deployment system includes an inner shaft telescopically received within a retractable sheath and a medical device positioned over the inner shaft. A handle assembly houses a hollow washer and includes a hollow handle body having an open distal end receiving the inner shaft and the retractable sheath. An open proximal end of the retractable sheath is attached to the washer and the inner shaft is received through an opening of the washer. In a pre-deployment configuration, the washer has an initial position within the handle body, an expandable fluid chamber within the handle body has an initial volume, and the retractable sheath restricts radial expansion of the medical device. In a post-deployment configuration, the washer has a retracted position proximally spaced from the initial position, the fluid chamber has an expanded volume, and the retractable sheath is retracted and permits radial expansion of the medical device.
