Endovascular Repair of the Aortic Arch and Ascending Thoracic Aorta

Background The aortic arch is wide, compliant, and mobile. Its flow rate is high and its branches supply an organ, the brain, with no tolerance for ischemia. In this location, an endovascular stent graft is difficult to deliver, difficult to secure, and prone to fatigue fracture, graft erosion, or migration. The only advantage is the opportunity for downstream access to vital arterial branches, and the presence of extensive collaterals to the subclavian artery. In the absence of a LIMA coronary bypass or a leftdominant vertebral artery, stent graft coverage of the subclavian artery appears to be well tolerated. Collateral flow usually suffices to prevent left hand ischemia at rest. Symptoms, when they occur, can be treated by carotid subclavian bypass. However, if more proximal segments of the aortic arch are to be excluded from the circulation, some provision has to be made for flow to the carotid arteries. The options include surgical bypass through a conventional graft from a remote artery, endovascular bypass through branches of the stent graft, various combinations of bypass and branching. Other options such as fenestration or double-barrel stent-graft insertion may also be used to lengthen the proximal implantation site without lengthening the seal zone.