Devices, systems, and methods of the present disclosure can overcome physical constraints associated with catheter introduction to facilitate the use of a catheter with a large distal portion as part of a medical procedure benefiting from such a large distal portion, such as, for example, cardiac ablation. More specifically, devices, systems, and methods of the present disclosure can compress an expandable tip of a catheter from an expanded state to a compressed state along a tapered surface of an insertion sleeve for advancement of the expandable tip into vasculature of a patient. The tapered surface of the insertion sleeve can, for example, apply compressive forces at an angle against the advancing expandable tip. As compared to other approaches to the application of compressive force to an expandable tip, compressing the expandable tip using an angled force can reduce the likelihood of unintended deformation of the expandable tip.