A 49-year-old man with drowsy mentality was diagnosed with acute type A aortic dissection; he underwent an emergency operation. When selective antegrade cerebral perfusion was initiated, the right regional cerebral oxygen saturation ($rSO_2$) decreased as compared to the left one. Adequate blood flow was perfused through the branch of the artificial graft, after distal anastomosis, but the right $rSO_2$ did not recover. Angiography revealed another intimal tear on the right common carotid artery. A stent was then inserted. The right $rSO_2$ promptly increased to the same level as that of the left one. The patient was discharged without any neurologic complications.