Stents with inwardly-directed protrusions are described. An exemplary stent has a main body having a longitudinal axis, a first end, a second end, an outer surface, and an inner surface. The main body defines a lumen extending from the first end to the second end. A protrusion is disposed on and extends inward from the inner surface of the main body. The protrusion extends along a path on the inner surface and has a pitch and a depth.
