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Thursday, September 15, 2016

From the SIR Residents and Fellows Section (RFS)

Teaching Topic: Endovascular Repair of Celiac Artery Aneurysm with the use of Stent Grafts

Zhang W, Fu YF, Wei PL, E B, Li DC, Xu J. Endovascular repair of celiac artery aneurysm with the use of stent grafts. J Vasc Interv Radiol. 2016. 27 (4): 514-8.

A recent article in JVIR evaluated the feasibility, safety, and long-term outcome of stent-graft insertion for endovascular repair of celiac artery aneurysms (CAAs). 10 patients with CAAs underwent endovascular repair via stent-graft insertion in a single center. Follow-up CTAs were performed at 1, 3, 6, and 12 months. There was no evidence of endoleak, stent obstruction, or splenic infarction during the follow-up period and all 10 patients had CAA sac shrinkage or increased CAA sac thrombus on follow-up imaging.

Clinical Pearls

What do we know about aneurysms involving visceral arteries?

Visceral arterial aneurysm (VAA) are rare, with an incidence of 0.1%–2%. Celiac artery aneurysms (CAA) constitute 4.8%–6.3% of all VAA cases. In this study, the treated aneurysms varied from 2.1 x 1.6 cm to 8.8 x 7.1 cm. They frequently present as a life-threatening emergency and are often fatal if associated with rupture. An aneurysm ≥ 20 mm in size is considered sufficient to warrant treatment if the patient’s overall condition permits it. Recent studies have reported treatment options for CAAs consisting of open surgery or embolization. Few publications have reported stent-graft insertion for endovascular repair in patients with CAAs.

What does the data show on endovascular treatment vs. open surgery?

In a recent article by Shukla et al. comparing outcomes between endovascular treatment (n = 122) and open surgery (n = 59) for VAAs, results show that endovascular treatment and open surgery are equally durable for patients with intact VAA, but endovascular treatment for ruptured VAAs was associated with a lower 30- day mortality rate (7.4% vs 28.6%; p<0.05) and better 2-year overall survival (69.4% vs 46.4%; p<0.05).

Questions to Consider

What are possible complications of CAA aneurysms and Stent Grafts for the CAA?

As mentioned above, the most dangerous complication of untreated CAAs is life-threatening hemorrhage. However, endovascular treatment of CAAs with stent grafts carries its own set of risks including dissection, stent thrombosis with end-organ ischemia, splenic infarction, and endoleaks.

While performing an endovascular Stent Grafting of a CAA, what do you have to watch for?

The anatomy of celiac artery aneurysms is complex, given that multiple branches can exit the aneuryms. Without identifying and potentially embolizing relevant branches, endoleaks may develop after stent graft placement. Equally, the interventionalist must define the distal landing zone for the endograft to assure a good seal and likelihood of long term patency. Pre-procedure planning with CTA and detailed catheter angiography are of utmost importance. As mentioned previously, endoleaks are of a concern as well, however, none resulted in the cases presented in the manuscript above. Many CAAs are associated with median arcuate ligament compression and post-stenotic dilation. Ligamentous compression may permanently deform balloon expandable stent grafts,

What are the limitations of the above study and why?

While the study sample was small (n=10), given low prevalence of the disease, this is nevertheless a meaningful number to show safety and efficacy. In addition, the retrospective nature introduces the possibility of selection bias. Can all CAAs be treated with stent graft? What can preclude a CAA from stent graft repair? If a CAA may be treated by embolization or stent graft, how should we decide the optimal treatment approach? 

What are the different types of Endoleaks?

While the classification system for endoleaks was originally intended for and applied to abdominal aortic aneurysms (AAAs), it can be used for discussion regarding stent graft treatment for aneurysm exclusion in other vascular territories.

Type I: Persistent filling of the aneurysm sac due to incomplete seal at the proximal or distal end of the stent graft.
Type II: Persistent filling of the aneurysm sack due to retrograde branch flow from collateral vessels.
Type III: Blood flow into the aneurysm sac due to ineffective sealing of overlapping graft joints.
Type IV: Blood flow into the aneurysm sac due to the porosity of the graft fabric, causing blood to pass through the graft joints or rupture of graft fabric.
Type V: Aneurysm sac expansion without clear evidence of endoleak origin.

Additional citations:
Shukla AJ, Eid R, Fish L, et al. Contemporary outcomes of intact and ruptured visceral artery aneurysms. J Vasc Surg 2015; 61:1442–1448.

Post author:
Ali Alikhani, MD
Diagnostic Radiology Resident, PGY-4
University of Tennessee Methodist Healthcare

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