Cognitive Effects of Body Temperature During Hypothermic Circulatory Arrest

Inclusion Criteria: * Patients who are scheduled for elective proximal aortic reconstructive surgery (ascending aorta + aortic valve or root) with concomitant proximal hemi- or total arch replacement via median sternotomy Exclusion Criteria: * \< 18 years of age * History of symptomatic cerebrovascular disease, eg, prior stroke with residual deficit * Alcoholism (\> 2 drinks/day) * Psychiatric illness (any clinical diagnoses requiring therapy) * Drug abuse (any illicit drug use in the past 3 months) * Hepatic insufficiency (liver function tests \> 1.5 times the upper limit of normal) * Severe pulmonary insufficiency (requiring home oxygen therapy) * Renal failure (serum creatinine \> 2.0 mg/dL) * Claustrophobic fear * Unable to read and thus unable to complete the cognitive testing * Pregnant women * Patients who score \< 24 on a baseline Mini Mental State Examination (MMSE) or ≥ 27 on the baseline Center for Epidemiological Studies Depression (CES-D) scale * Patients who have pre-existing unsafe implants for 3 Tesla magnetic resonance imaging (MRI). * Patients who have received chemotherapy in the last 12 months. * Patients with COVID-19 diagnosis within the past 12 months