Duplex ultrasound follow-up after fenestrated and branched endovascular aneurysm repair (FEVAR and BEVAR).

Endovascular aneurysm repair (EVAR) is now the predominant method for treatment of infrarenal abdominal aortic aneurysms. Although EVAR has numerous advantages over standard open surgical repair, it also exposes patients to risks such as aneurysm sac enlargement, endoleaks, and graft migration, which make surveillance or follow-up mandatory. Fenestrated (FEVAR) and branched (BEVAR) endografts have extended the application of EVAR to juxtarenal, pararenal/paravisceral, and thoracoabdominal aneurysms, with some complex aneurysms requiring combined approaches (F-BEVAR). Duplex ultrasound has been recommended as an alternative to frequent computed tomography imaging for EVAR follow-up when it can provide the clinically necessary information. The major components of a post-EVAR duplex examination include measurement of aortic aneurysm sac size, assessment for endoleak, and evaluation of the endograft for patency and integrity. The duplex protocol for EVAR follow-up can be extended for follow-up after FEVAR, BEVAR, and F-BEVAR, with additional attention to the device components associated with fenestrations and branches. At the University of Washington, the physician-modified endovascular graft approach has been used for FEVAR. During these procedures, covered stents are placed in the renal arteries through fenestrations and the superior mesenteric artery is perfused through a fenestration, but typically remains unstented. Duplex scanning of the renal and mesenteric arteries has been performed preoperatively and at 30 days, 6 months, 1 year, and annually. In a review of patients having covered stents placed in non-stenotic renal arteries during FEVAR, both peak systolic velocity and the renal to aortic velocity ratio remained below the standard significant stenosis threshold in most patients. The duplex velocity criteria for stenosis in native renal arteries appeared to overestimate the severity of stenosis in renal artery covered stents. The unstented superior mesenteric artery remained widely patent in the presence of fenestrations or crossing struts and was not associated with endoleaks. Duplex ultrasound protocols for follow-up after FEVAR, BEVAR, and F-BEVAR can be based on those that have been established for standard EVAR, along with assessment of fenestrations and branches, as well as patency of the renal and mesenteric arteries.
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