Abrupt 90° and 180° changes in stent geometry (particularly in the side branches) cause a high momentum change and thus increased flow separation and mixing, which has significant implications in blood flow characteristics near the wall. By comparison, longer bridging stents provide more gradual changes in momentum, thus allowing blood flow to develop before reaching the target vessel.
The stent graft configuration with the diaphragm does have particles with shear accumulation >3.5 Pa-s. However, the percentage of particles with shear accumulation above 3.5 Pa-s is less than the two commercially available mechanical aortic valves, and more surprisingly, is smaller than in the healthy aorta.
Patients suffering from aortic arch aneurysms continue to encounter few treatment options. Because of co-morbidities, most are deemed to not be open surgical candidates. The two cases presented here demonstrate a novel endovascular approach in the care of an arch aneurysm complicated by dissection. Even though final graft configurations differed slightly between the two cases, all three great vessels were successfully de-branched through the combination of standard endovascular aneurysm repair techniques and modifications to off-the-shelf devices. Aortic flow was compartmentalized in the ascending aorta at or near the level of the sinotubular junction. This was done with a physician-assembled endografts. One of these lumens was dedicated to the descending aorta, while the other was further divided into three channels used to stent the great vessels. Completion angiography demonstrated patency in the arch, great vessels, and descending aorta. No endoleaks have been reported. Although data is limited, this approach appears promising.
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