An apparatus and method for treating stenosed blood vessels is provided, more particularly a percutaneous catheter, including a filter for capturing loose embolic material, used to deliver a stent, preferably within the ascending aorta, the aortic arch, or the carotid arteries. The catheter includes an expandable stent deployed on an inflatable balloon, or alternatively a self-expanding stent. A filter assembly is provided either directly on the catheter, or in a separate sheath or on a guidewire. The filter assembly comprises an expansion frame, having filter mesh attached to it, disposed on a guidewire inserted through the catheter or sheath, or alternatively attached directly on a distal region of the catheter. The expansion frame 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. The expansion frame includes biased struts, a mechanically operated frame, and/or a fluid-operated frame. The catheter is percutaneously introduced into a blood vessel and directed to a target region. The stent is localized across the region, the filter assembly is opened, and the stent is deployed, substantially permanently engaging the walls of the blood vessel, thereby opening the stenosed region and/or containing aortic plaque.