Techniques are described for treating an occlusion in a patient. In one example, a system includes an atherectomy device configured to remove an occlusion from a body lumen and a positioning device that positions the atherectomy device adjacent to the occlusion. The positioning device includes a tubular body having first and second ends and defining a lumen therebetween, at least two fins engaged to the tubular body, wherein in a deployed state, the fins extend radially outward from the tubular body, and wherein in an undeployed state, the at least two fins wrap about one another and about the tubular body, a guide wire extending through the lumen, and first and second stopper members, each of the first and second stopper members engaged to the guide wire, wherein the first stopper member and the second stopper member substantially prevent movement of the tubular body along the guide wire.