A device and method for protecting a blood vessel, and hence bodily tissues, against damage caused by particulate such as an embolus. The device may be a stent, for insertion in a large artery such as the ascending aorta, and may be combined with a filter. In one embodiment, the device includes an outer wire frame rather than a stent. The stent may be made of at least one layer of mesh, which is typically attached or mounted to the arterial wall. Typically only part of the stent is attached (for example at a reinforcing ring structure). Typically the size of the apertures of the mesh at the top portion of the stent is smaller than the bottom portion of the stent. The device and method are particularly useful in preventing blockages of flow to the brain, but have other uses as well. An electric charge may be placed on the device, for example, to prevent blood components from collecting.