EXtensive mulTilayer stEnt treatmeNt in Aortic disSectiOn

This clinical trial is a prospective, multicenter, open label study designed to evaluate the effectiveness and the safety of the Allay® Aortic Stent as adjunctive endovascular treatment of Type B aortic dissection in patients eligible for thoracic endovascular aortic repair with stent grafts.

Inclusion Criteria: * Have a type B aortic dissection extending to the celiac trunk or beyond * Are eligible for thoracic endovascular treatment with stent grafts as per local guidelines, and physician's decision * Have been elected for treatment with commercially available stent graft as per their IFU within 90 days of dissection symptoms onset Exclusion Criteria: * General Exclusion Criteria: * Age \< 18 years * Pregnant, breast-feeding or planning on becoming pregnant during the entire duration of the study * Unable to provide written informed consent * Unable or unwilling to comply with the requirements of the study protocol * Taking part already in an investigational device or drug study that could interfere with the outcomes being studied * Active drug addiction or known history of drug abuse within one year of treatment * Medical Exclusion Criteria: * Aortic rupture (free or contained including haemothorax, increasing periaortic hematoma, or mediastinal hematoma) * Aortic fistula * Suspicion of bowel necrosis or irreversible visceral ischemia * Stage 5 chronic kidney disease * Life expectancy of less than 2 years due to any other medical condition than the dissection to be treated * Active malignancy * Known sensitivities or allergies to the device materials (including cobalt, chromium, nickel) * Known sensitivities or allergies to contrast materials that cannot be pre-medicated * Mycotic aortic aneurysm or active systemic infection that may place the patient at increased risk of endovascular infection * American Society of Anaesthesiologists (ASA) class V (moribund patient not expected to live 24 hours with or without operation) * Diagnosed or suspected congenital degenerative connective tissue disease (e.g., Marfan's, Loeys-Dietz or Ehlers-Danlos syndrome) * Uncorrectable coagulopathy, bleeding diathesis or refusal of blood transfusion * Any major cardiovascular or cerebrovascular ischemic event, including myocardial infarction or stroke, or treatment of such event, within 90 days prior to enrolment * Any aortic-related interventional or surgical procedure within 30 days prior to enrolment * Any planned aortic-related interventional or surgical procedure within 30 days after the study procedure * Anatomical Exclusion Criteria: * Aneurysmal dilatation of the false lumen defined as maximum transaortic diameter \>55 mm in women or \>60 mm in men in the thoraco-abdominal segment or \>50 mm in women or \>55 mm in men in the abdominal segment, measured inner-wall to inner-wall; * Inadequate proximal landing zone for the stent graft, such zone being \38 mm or \