This disclosure describes techniques for securing an elongated member, such as a medical lead, within a tissue of a patient. In particular, suction is applied from a vacuum to a vacuum cavity located proximate to a distal end of the lead to draw in tissue from the target therapy delivery site to the vacuum cavity. A fixation element is coupled to the tissue within the vacuum cavity to fix the lead to the target therapy delivery site. The fixation techniques of this disclosure secure the medical lead to the tissue of the patient to prevent the medical lead from migrating away from the target tissue location.