A percutaneous stent deployment assembly used in the treatment of stenosed blood vessels is provided, including a filter (30) for capturing loose embolic material the assembly being used to deliver a stent (20) preferably within the ascending aorta, the aortic arch, or the carotid arteries. The assembly comprises an expansion frame (52) having filter mesh (60) attached to it disposed on a guidewire (40) inserted through a catheter (10), or sheath (32), or alternatively attached directly on a distal region of the catheter (10). The expansion frame (52) comprises a structure which is activated from a contracted condition into an enlarged condition in a blood vessel, thereby traversing the vessel with the filter mesh (60). The expansion frame (52) includes biased struts, a mechanically operated frame, and/or a fluid operated frame. A catheter (10) is percutaneously introduced into a blood vessel and directed to a target region. The stent (20) is localised across the region. The filter assembly (30) is opened, and the stent (20) is deployed substantially permanently engaging the walls of the blood vessel, thereby opening the stenosed region and/or containing aortic plaque. <;IMAGE>;