The active introducer sheath systems disclosed herein are expanded by activating a translation mechanism at the handle. The sheath has an inner cylindrical structure of comingled fixed and mobile elongate rods bound together by an attachment line. Activating the translation mechanism causes the mobile rods to move axially with respect to the fixed rods, changing the internal tension in the attachment line. Increased tension draws the fixed and mobile rods closer together, decreasing the diameter of the cylindrical structure. Decreased tension in the attachment line enables the fixed and mobile rods to move apart, increasing the diameter of the cylindrical structure. A prosthetic device, such as a prosthetic heart valve, can be routed through the expanded sheath and to the implantation site. During implantation, the sheath can be contracted back to its original outer diameter, and expanded again for retrieval of the delivery apparatus.