Implantable medical device deployment within a vessel

In one example, this disclosure is directed to a method for intravascular implantation of an implantable medical device comprising positioning a distal end of an elongated outer sheath forming an inner lumen adjacent a target site within a vasculature of a patient, and partially deploying an implantable medical device from the distal opening, wherein the implantable medical device includes an expandable fixation element. A portion of the expandable fixation element assumes an expanded position when the implantable medical device is partially deployed from the distal opening. The method including advancing the distal end of the outer sheath within the vasculature with the implantable medical device partially deployed from the distal opening, and monitoring at least one of the vasculature and the portion of the expandable fixation element for deflection to determine when the size of the portion of the expandable fixation element corresponds to the size of the vasculature.