An embolism deflection device and method for preventing embolization during a surgical procedure include a dome-shaped deflector, a catheter coupled to the deflector, and a delivery sheath. The deflector includes a frame and porous cover, the cover permitting blood flow therethrough while blocking emboli. The deflection device is deployable from a branch vessel to cover an ostium of the branch vessel to block emboli from a main vessel from entering the branch vessel.
