EXtensive MulTilayer StEnt TreatmeNt in Aortic DisSectiOn

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 localguidelines, and physician's decision

• Have been elected for treatment with commercially available stent graft as per theirIFU 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 entireduration 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 couldinterfere with the outcomes being studied

• Active drug addiction or known history of drug abuse within one year oftreatment

• Medical Exclusion Criteria:

• Aortic rupture, free or contained including haemothorax, increasing periaortichematoma, 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 thanthe 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 bepre-medicated

• Mycotic aortic aneurysm or active systemic infection that may place the patientat increased risk of endovascular infection

• American Society of Anaesthesiologists (ASA) class V (moribund patient notexpected 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, includingmyocardial infarction or stroke, or treatment of such event, within 90 daysprior to enrolment

• Any aortic-related interventional or surgical procedure within 30 days prior toenrolment

• Any planned aortic-related interventional or surgical procedure within 30 daysafter the study procedure

• Anatomical Exclusion Criteria:

• Aneurysmal dilatation of the false lumen defined as maximum transaorticdiameter >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-wallto inner-wall;

• Inadequate proximal landing zone for the stent graft, such zone being <20 mmlong

• Inadequate proximal landing zone geometry for the Allay® Aortic Stent (e.g.aortic kink)

• Planned implantation of a stent graft with a distal diameter >38 mm or <20 mm

• Aorta or iliac anatomy not allowing the advancement of the delivery system

• Subject in whom the thoracic stent graft is either 1) not implanted in itsintended position and/or 2) leads to any serious device complication, and/orwho has 3) persistent static obstruction of the visceral or both renalarteries, prior to Allay® Aortic Stent implantation, will not be implanted withthe Allay® Aortic Stent and will be withdrawn from the study