Malignant Hyperthermia (MH) is a life-threatening biochemical process of hypermetabolism brought about in susceptible individuals by a triggering drug or event. Type A aortic dissections are surgical emergencies requiring cardiopulmonary bypass and frequently deep hypothermic circulatory arrest. We present a case of suspected MH in a patient undergoing emergent repair of a type A aortic dissection. Upon arrival at our institution, the patient had multiple signs of MH. However, no known triggering agent had been administered. Eventually, the unique physiologic changes of cardiopulmonary bypass provided strong support for the diagnosis of MH and dantrolene was administered, effectively treating the episode.