The invention relates to a percutaneous filter system comprising a guidewire, a support wire having a proximal end, a distal end, a distal region, and an expandable filter mounted on the distal region of the support wire, the support wire adapted to receive a percutaneous medical instrument； and a sheath which removably covers the support wire and filter, the sheath having a proximal end, a distal end, a distal region, the distal region having a lumen which receives the filter and an aperture adapted to pass the guidewire, wherein, during use, the guidewire is positioned in a vessel at a region of interest, the sheath carrying the support wire is advanced along the guidewire until the filter reaches the region of interest, and the sheath is withdrawn to expose the filter. The sheath slides on the guide wire with a rapid exchange mechanism.
