Branched Aortic Arch Study

An aneurysm is a localized bulge in the wall of an artery. Aneurysms of the aorta are prone to progressive dilatation, which if left untreated ultimately results in rupture, internal bleeding and death. Traditional open surgery involves aortic exposure through a long incision, aortic clamping to interrupt blood flow, and replacement or repair of the dilated aortic segment using a fabric conduit (graft), which is sutured (anastomosis) to the nondilated arteries above and below the aneurysm. Some subjects are able to withstand such a large operation better than others, but many suffer complications, and all suffer pain, debility, and a lengthy stay in hospital. Endovascular aneurysm repair is a less invasive alternative that substitutes a trans-arterial route to the aneurysm for direct exposure, and stent-mediated attachment for sutured anastomosis. Compared to open surgical repair, endovascular repair is associated with less physiological derangement, less pain, less blood loss, lower complication rates and shorter hospital stay. Consequently, endovascular repair has become standard therapy for aneurysms of the abdominal aorta and descending thoracic aorta, where there are no vital branches and endovascular exclusion rarely causes ischemic complications. Open surgical repair of the proximal aortic arch requires hypothermic circulatory arrest, because it deprives the heart of its outflow and the brain of its inflow. Endovascular repair also obstructs outflow from the heart, but only for a few seconds, while the graft is released from its delivery sheath. The greater problem is inflow to the brain. In anticipation of aortic arch exclusion, the brachiocephalic circulation requires an alternative source of blood. One alternative is bypass from the ascending aorta. However, this requires median sternotomy and partial aortic clamping, both of with are potential sources of morbidity.