An apparatus (10 - figure 12) for preventing stroke by occluding blood flow through a right carotid artery and a left carotid artery of a patient, comprising: a first occluding catheter that carries a first occluding balloon that has an inflated configuration that is configured to occlude either the right carotid artery or the left carotid artery; a second occluding catheter that carries a second occluding balloon that has an inflated configuration that is configured to occlude the other one of the right carotid artery or the left carotid artery that is not occluded by the first occluding balloon; and an insertion device that defines a first occluding catheter channel and a second occluding catheter channel; wherein the first occluding catheter is located in the first occluding catheter channel and is movable through the first occluding catheter channel such that the first occluding catheter is movable relative to the insertion device; and wherein the second occluding catheter is located in the second occluding catheter channel and is movable through the second occluding catheter channel such that the second occluding catheter is movable relative to the insertion device and is movable relative to the first occluding catheter; wherein the insertion device has a first proximal opening from which the first occluding catheter channel extends to a first distal opening of the insertion device, wherein the insertion device has a second proximal opening from which the second occluding catheter channel extends to a second distal opening of the insertion device; wherein the orientations and positions of the insertion device first distal opening and the insertion device second distal opening specifically correspond to the locations and orifices of an innominate artery and the left carotid artery and having an average distance between these two orifices ranging from 0.5 centimeters to 5.5 centimeters for direct catheterization and occlusion of the innominate artery and the left carotid artery, wherein the insertion device first distal opening and the insertion device second distal opening are located on the same side of the insertion device and configured to both face the orifices of the innominate artery and the left carotid artery. a first occluding catheter that carries a first occluding balloon that has an inflated configuration that is configured to occlude either the right carotid artery or the left carotid artery; a second occluding catheter that carries a second occluding balloon that has an inflated configuration that is configured to occlude the other one of the right carotid artery or the left carotid artery that is not occluded by the first occluding balloon; and an insertion device that defines a first occluding catheter channel and a second occluding catheter channel; wherein the first occluding catheter is located in the first occluding catheter channel and is movable through the first occluding catheter channel such that the first occluding catheter is movable relative to the insertion device; and wherein the second occluding catheter is located in the second occluding catheter channel and is movable through the second occluding catheter channel such that the second occluding catheter is movable relative to the insertion device and is movable relative to the first occluding catheter; wherein the insertion device has a first proximal opening from which the first occluding catheter channel extends to a first distal opening of the insertion device, wherein the insertion device has a second proximal opening from which the second occluding catheter channel extends to a second distal opening of the insertion device; wherein the orientations and positions of the insertion device first distal opening and the insertion device second distal opening specifically correspond to the locations and orifices of an innominate artery and the left carotid artery and having an average distance between these two orifices ranging from 0.5 centimeters to 5.5 centimeters for direct catheterization and occlusion of the innominate artery and the left carotid artery, wherein the insertion device first distal opening and the insertion device second distal opening are located on the same side of the insertion device and configured to both face the orifices of the innominate artery and the left carotid artery.