A self-expanding filtration element is fitted to the distal end of a catheter while a sheath for constraining such element to a reduced diameter is mechanically manipulatable from the proximal end of the device. The entire device is maneuvered into position over a guide wire and deployed prior to treatment of the body lumen at an upstream location. After completion of the treatment procedure, the filtration element is collapsed and constrained within the sheath to retain any embolic material that has been captured and allow it to be safely removed from the vasculature. The device may be combined with a primary treatment modality and its low profile allows the constrained filtration element to be removed through a deployed stent.