A device for percutaneously delivering a stented prosthetic heart valve. The device includes an inner shaft assembly, a delivery sheath assembly, an outer stability tube, and a handle. The sheath assembly is slidably disposed over the inner shaft, and includes a capsule and a shaft. The capsule compressively contains the prosthesis over the inner shaft. The stability tube is slidably disposed over the delivery sheath, and includes a distal region configured to be radially expandable from a first shape having a first diameter to a second shape having a larger, second diameter. In a first delivery state, the distal region assumes the first shape, providing a low profile appropriate for traversing a patient's vasculature. In a second delivery state, the distal region has the expanded diameter second shape, sized to receive the capsule, such as when retracting the capsule to implant the prosthesis.