Retrograde Versus Antegrade Perfusion in Low-Moderate Hypothermia for Aortic Arch Surgery

The purpose of this study is to compare brain function after surgical circulatory arrest (surgeon stops the heart-lung machine to work on the heart) in antegrade perfusion versus retrograde perfusion. There are 2 ways to supply blood to the brain, antegrade and retrograde perfusion. In antegrade perfusion, the surgeon accesses one of two arteries that branch off from the aorta (the artery that delivers blood to the rest of the body) to provide blood to the brain. In retrograde perfusion, the surgeon accesses the superior vena cava (large vein bringing blood back to the heart) to supply blood to the brain. It is standard practice to cool the patient down during this type of surgery to help protect the brain. Despite measures to safeguard brain health, some patients still experience postoperative cognitive decline such as confusion, delirium and agitation. The investigators are conducting this study to see which method of perfusing the brain is superior and decreases the symptoms of confusion, delirium and agitation.