Endovascular Treatment of Aneurysms of the Juxtarenal and Pararenal Aorta

Historical Background

Juxtarenal aneurysms refer to abdominal aortic aneurysms with an infrarenal neck less than or equal to 1 cm in length, and pararenal aneurysms refer to abdominal aortic aneurysms that involve one or both orifices of the renal arteries. Browne and associates first described the design of a fenestrated graft in 1999 in which holes were placed within an endograft for deployment of uncovered balloon-expandable stents from the aortic graft into the renal arteries. The principle of fenestrated technology was extended above the infrarenal segment by Anderson in 2005 to treat aneurysms involving the visceral arteries. The first report of branched endograft used for the treatment of a thoracoabdominal aneurysm was reported in 2001 by Chuter and colleagues. Branched and fenestrated grafts offer a complete endovascular solution. Fenestrated grafts are now commercially available in the United States. As an alternative to fenestrated and branched endografts, Greenberg and associates were the first to describe a “snorkel” or “chimney graft” technique in 2003, with placement of a stent into the renal artery alongside the endograft to treat a juxtarenal aortic aneurysm. Others have extended this technique to treat pararenal aneurysms during endovascular aneurysm repair (EVAR). Hybrid, or combined open and endovascular, approaches are another option for treatment of complex aortic aneurysms involving visceral vessels and were first reported in 1999 by Quinones-Baldrich and co-workers.

Preoperative Preparation

• A detailed analysis is required of axial images and three-dimensional reconstructed images of the aorta using TeraRecon (San Mateo, Calif.) or M2S (West Lebanon, N.H.) devices. The radial orientation of visceral vessels is often related to in terms of the hands of a clock.

• The diameter of each vessel and the distance of each vessel origin from the edge of the graft, as well as from each other, are recorded. The endograft is manufactured accordingly.

• Preoperative hydration should be considered for patients with compromised renal function.

• Spinal catheter drainage is recommended if coverage of a long segment of thoracic aorta is planned in addition to treatment of the visceral segment of the aorta.

• Perioperative antibiotics and subcutaneous heparin for prophylaxis of deep venous thrombosis are routinely administered.

Endovascular Strategy

Endovascular repair of the visceral segment of the aorta uses stent-graft exclusion of the aneurysm with preservation of flow to important branch vessels ( Video 27-1, Video 27-2, Video 27-3, Video 27-4, Video 27-5, Video 27-6, Video 27-7, Video 27-8, Video 27-9, Video 27-10, Video 27-11, Video 27-12 ). Flow to the renal, celiac, and superior mesenteric arteries is preserved with transarterial access. When the branch vessel arises from where the stent graft is attached, a simple hole, or fenestration in the stent graft, is sufficient. When the branch vessel arises from an aneurysmal portion of the aorta, however, flow between the stent-graft component and the branch vessel must be achieved with a branched graft to traverse the distance between the stent and the origin of the vessel.

Fenestrated Grafts

Current fenestrated stent grafts are manufactured by Cook Medical (Bloomington, Ind.). The graft is composed of woven polyester and the stent component is of stainless steel. Radiopaque markers on the front and back of the graft provide reference points for orientation. Fenestrations are categorized into three types: scallops, small fenestrations, and large fenestrations ( Fig. 27-1 ). Scallops are open to the free margin of the graft, small fenestrations occupy the spaces between stent struts, and large fenestrations are crossed by stent struts. The fenestrations are sized and positioned on the stent graft according to the relative positions of the origins of the branch vessels. Because of device constraints, with small fenestrations located between stents, the stent graft cannot be a perfect replica of aortic anatomy. Tortuosity in the path from the femoral artery to the aorta can dramatically shift the geometric relationships between the origins of the branch vessels and their corresponding fenestrations. The more fenestrations in a stent graft, the fewer degrees of freedom allowable with respect to slight adjustments in orientation during deployment. There is some flexibility in the system because of stent-graft oversizing, where the orifice of the fenestration can be forced into the proper position with a guiding catheter. The use of a bridging stent allows patency when this alignment is strained.