Cerebral Autoregulation Monitoring During Cardiac Surgery

Neurological complications from cardiac surgery are an important source of operative mortality, prolonged hospitalization, health care expenditure, and impaired quality of life. New strategies of care are needed to avoid rising complications for the growing number of aged patients undergoing cardiac surgery. This study will evaluate novel methods for reducing brain injury during surgery from inadequate brain blood flow using techniques that could be widely employed.

Inclusion Criteria: * Male or female patients undergoing primary or re-operative Coronary Artery Bypass Graft (CABG) and/or valvular surgery or ascending aorta surgery that requires Cardio-pulmonary bypass (CPB) who are at high risk for neurologic complications (stroke or encephalopathy) as determined by a Johns Hopkins risk score of \>0.02 Exclusion Criteria: * Contraindication to MRI imaging (e.g., permanent pacemaker, cerebral arterial vascular clips) * Liver function test before surgery more than twice the upper limit of institutional normal * Pre-existing renal dysfunction defined as an estimated glomerular filtration rate of ≤60 mL/min, or current renal dialysis * Emergency surgery * Inability to attend outpatient visits * Visual impairment or inability to speak and read English. The patient will be excluded from further study if an adequate temporal window for Transcranial Doppler (TCD) monitoring can not be identified before surgery.