A catheter can include a shaft; an inflatable balloon having a proximal end that is anchored to an end of the shaft; an elongate member that is separate from and disposed inside the shaft, extends into an interior chamber of the balloon, and is anchored to a distal end of the balloon; and a spring member that exerts a distally-oriented longitudinal force on the elongate member, relative to the shaft, where the distally-oriented longitudinal force causes the balloon to be biased in an extended position, away from the end of the shaft. The catheter can further include a sheath that surrounds the shaft and balloon before a treatment procedure. The balloon can be configured to be advanced outside the sheath during a treatment procedure and inflated, and the spring member can be configured to facilitate deflation and withdrawal of the balloon into the sheath following the procedure.