Intravascular Ultrasound for the Evaluation of Malperfusion Syndrome in the Setting of Acute Aortic Dissection

Inclusion Criteria: * Patients diagnosed with an AAD or acute on chronic aortic dissection, with a new diagnosis of malperfusion syndrome (Malperfusion Primary Cohort), by meeting both of the following criteria: * Imaging findings indicating reduced flow to the Celiac Trunk, Superior mesenteric artery, either renal artery or either iliac artery * Clinical stigmata of end organ ischemia (abdominal pain, distended abdomen, oliguria/anuria, reduced pulses, signs of limb ischemia) correlating with imaging findings * OR o Laboratory findings suggestive of end organ ischemia (lactic acidosis, elevated LFTs, Elevated Creatinine, Rhabdomyolysis, Electrolyte abnormalities) correlating with imaging findings * Patients diagnosed with an AAD undergoing surgical repair without evidence of malperfusion syndrome preoperatively, but who develop malperfusion syndrome due to dynamic flow changes after true lumen flow is reinstituted intraoperatively as indicated by new clinical signs or new laboratory results meeting the following criteria (Malperfusion Secondary Cohort): * New Clinical signs include: Loss of femoral pulses, distended abdomen, reduced urine output, dusky/cold extremities * New Laboratory results include: Rising lactate (\>50% above baseline), Rising Creatinine, Metabolic Acidosis, Rising LFTs * Patients diagnosed with an AAD undergoing surgical repair without evidence of malperfusion syndrome preoperatively and postoperatively (No Malperfusion Cohort). Exclusion…