A medical device having enhanced steerability for navigation through a patient's vasculature and for positioning the device for performing a medical procedure, such as pulmonary vein isolation. The device generally includes an elongate body, a balloon defining a proximal neck that is affixed to the distal end of the elongate body such that the neck and elongate body are coterminous, a shaft disposed at least partially within the elongate body and at least partially within the balloon, and a pull wire affixed to a distal portion of the shaft, such that pulling the pull wire will cause deflection of the balloon at a point that is immediately distal of the proximal neck of the balloon. Further, the shape of the balloon when deflected and when in a neutral configuration may be substantially the same.