When treating certain medical conditions, it is sometimes desirable to expand a frame or other radially expandable member in an orifice or conduit of a patient's body. For example, expandable tubes called stents are commonly inserted into a natural conduit of a patient's body and expanded inside the conduit to hold the conduit in an open position. Such expandable stents can be used to expand, widen, or otherwise provide structural support to various conduits of the human body, including, for example, arteries, veins, bile ducts, the esophagus, and the colon. In other treatment procedures, prosthetic heart valves that include a frame member are implanted into the body at a treatment site (e.g., a heart valve annulus). These prosthetic heart valves can be positioned in the heart valve annulus by expanding the frame member to roughly the size of the valve annulus.
Such frames or stents can be self-expanding or expanded using an expansion balloon. One conventional method involves positioning a frame on a balloon of a balloon catheter, maneuvering the balloon and frame to the treatment site, and inflating the balloon with a fluid to expand the frame or stent to the desired size. Such an approach, however, can have drawbacks. For example, during the expansion of the balloon the orifice or conduit is usually at least partially, if not completely, occluded, which can cause certain undesirable effects. Accordingly, it is desirable to provide methods and delivery systems that eliminate or reduce these and other potential drawbacks.