Fenestrated endovascular aortic repair of a superior mesenteric artery aneurysm using carbon dioxide angiography and intravascular ultrasound

Superior mesenteric artery aneurysms are rare; however, current guidelines suggest they all require repair due to the high rupture and mortality rates, and endovascular repair is an effective management strategy. Iodinated contrast traditionally used in endovascular repair can cause significant complications, including severe allergic reactions and contrast-induced nephropathy in patients with chronic renal disease. Therefore, other imaging methods should be used during endovascular procedures to reduce these risks. We describe a unique and innovative approach using carbon dioxide angiography and intravascular ultrasound during fenestrated endovascular repair of an uncommon superior mesenteric artery aneurysm in a patient with severe contrast allergies.

][3][4] Current guidelines suggest all SMAAs require repair due to the high rupture and mortality rates.Open and endovascular surgical procedures are available. 3,4However, fluoroscopy with iodinated contrast during endovascular repair can cause complications, including severe allergic reactions and contrast-induced nephropathy in patients with chronic renal disease.7][8][9] However, its use during fenestrated EVAR (FEVAR) remains nearly unexplored. 10][13] We describe an innovative use of CO 2 angiography and IVUS during FEVAR of a complex SMAA.Using this unique approach, we eliminated the use of iodinated contrast in a patient with severe contrast allergies.The patient provided written informed consent for the report of his case details and imaging studies.

CASE REPORT
A 67-year-old man underwent endovascular repair of a SMAA with a custom fenestrated aortic graft.The initial computed tomography angiogram revealed a very large saccular SMAA measuring 8.9 cm anteroposteriorly, 6.3 cm craniocaudally, and 6.4 cm transversely (Fig 1).Although the SMA vessel origin was involved, the aorta itself was not aneurysmal along its course.

Endovascular aortic repair was chosen over an open repair
given the patient's medical comorbidities, including obesity, hepatitis C, Child Pugh A cirrhosis with previous ascites, hypertension, and hypertriglyceridemia.Because the SMA origin offered no proximal landing zone, a fenestrated graft was selected to provide a proximal seal.CO 2 angiography and IVUS were chosen as the imaging techniques because of the patient's previously documented anaphylactic reaction to contrast dye, including a pruritic rash, airway swelling, and nausea, despite appropriate premedication.
An Anaconda custom fenestrated aortic stent graft (Terumo Aortic; not available in the United States) was placed using CO 2 angiography using bilateral percutaneous femoral artery access (Fig 2, A and B).Next, the celiac graft fenestration and artery were cannulated under CO 2 angiography using a C1 catheter

DISCUSSION
SMAAs represent 3.5% to 15% of visceral artery aneurysms.2][3] In the present case, the saccular aneurysm, >6 cm in size, involved the SMA origin (Fig 1).Although older literature suggests most SMAAs were of mycotic etiology, recent evidence suggests most are degenerative. 1,2Other risk factors for SMAA development include aging, atherosclerosis, connective tissue disease, inflammatory conditions, trauma, and fibromuscular dysplasia. 1,2,14,15Our patient had no identified history of pancreatitis and a remote history of sepsis secondary to severe pneumonia.A preoperative white blood cell scan demonstrated no abnormal activity in the aneurysm, making a degenerative etiology more likely than a mycotic etiology.Severe complications of SMAAs include rupture, mortality, thrombosis, and distal embolization causing intestinal ischemia. 1,2,14,15ecent data suggest that splanchnic artery aneurysms #2.0 to 2.5 cm in size are safe to observe 2,14,15 ; however, the current Society for Vascular Surgery guidelines recommend operative repair due to the high rupture rates. 3Although asymptomatic, the large aneurysmal size and saccular features were indications for repair in our case.
The options for open surgical SMAA repair include ligation, aneurysmorrhaphy, interposition bypass, and aorticemesenteric bypass grafting. 2,4Endovascular options include coil embolization and stenting. 2,4,16Despite the benefits of endovascular management, the aneurysm anatomy, pathogenesis, patient comorbidities, and surgical history dictate the management approach. 4,16Our patient's medical comorbidities were a significant factor in choosing an endovascular approach in this case.6][7] Our patient had a prior documentation of an anaphylactic reaction to contrast despite appropriate premedication.
Although infrequent, imaging methods without iodinated contrast, including CO 2 angiography, have been studied during endovascular aortic procedures.Specifically, CO 2 angiography during EVAR was associated with decreased renal toxicity, while maintaining technical success, morbidity, and mortality rates similar to those for procedures performed with iodinated contrast. 8,9,11The use of IVUS during EVAR can also reduce the need for iodinated contrast.2][13] The usage of CO 2 angiography and IVUS during FEVAR, however, remains nearly unexplored.
Our innovative technique demonstrates that CO 2 angiography and IVUS can function as complementary tools during FEVAR.Using these tools, a uniquely large and complex SMAA was successfully repaired with FEVAR without the use of any iodinated contrast medium.Only one recent study has compared the combined use of CO 2 angiography and fluoroscopy vs fluoroscopy alone during FEVAR. 10The addition of CO 2 angiography lowered the rates of postoperative renal insults, with better preserved renal function at 30 days, decreased contrast medium usage, and shortened hospital stays. 10ewer research suggests that the benefits of CO 2 angiography on renal function are not limited to the postoperative period, with a greater degree of preservation of renal function at 1 year after EVAR. 17Another study demonstrated that CO 2 angiography is especially helpful for identifying the patency and position of target vessels when misaligned with stent fenestrations. 18The evidence from these studies, and the success in this innovative technique, demonstrate that performing this procedure without the use of iodinated contrast expands the current treatment options for patients with contraindications to contrast.

CONCLUSIONS
This case demonstrates the successful use of CO 2 angiography and IVUS during FEVAR of a uniquely large and complex SMAA.With this novel approach, we eliminated the need for iodinated contrast in a patient with severe allergies.Our technique not only demonstrates that CO 2 angiography and IVUS are useful options during FEVAR but also expands the options for patients with contraindications to contrast medium.

(
Cook Medical Inc).An 8 Â 38-mm covered balloonexpandable Advanta V12 stent (Atrium Medical, Getinge) was placed and flared proximally into the main body with a 10mm Mustang balloon (Boston Scientific).CO 2 angiography confirmed stent placement and flow.Next, the Volcano IVUS imaging system (Philips Healthcare) was used to visualize the remaining visceral branches.The SMA fenestration and SMAA were crossed with the C1 catheter and 8F Destination sheath (Terumo Interventional Systems; Fig 2, C).IVUS was used to identify the SMA branch vessels and a landing zone in healthy distal SMA, where an 8 Â 79-mm covered balloon expandable VBX stent (Gore Medical) was placed.A second overlapping 8 Â 59mm VBX stent was deployed proximally and flared within the main body (Fig 2, D).CO 2 angiography confirmed stent placement and flow, with sac exclusion (Fig 2, E).The renal arteries

Fig 2 .
Fig 2. Carbon dioxide (CO 2 ) angiography images obtained during fenestrated endovascular repair of the abdominal aorta (FEVAR) for a superior mesenteric artery (SMA) aneurysm (SMAA).(A) Sagittal CO 2 angiography was used to visualize the visceral vessels for main body device placement planning (B).(C) A C1 catheter and 8F Destination sheath were used to cross the SMA fenestration and SMAA for deployment of an 8 Â 79-mm balloon expandable VBX stent (D, E). (F) Completion CO 2 angiogram demonstrating flow into the visceral abdominal vessels with no obvious endoleak.

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Van Essen et al Journal of Vascular Surgery Cases, Innovations and Techniques April 2024 were similarly cannulated using the C1 catheter and an 8F Destination sheath and reconstructed using 6 Â 38-mm Advanta V12 stents bilaterally flared in the fenestrated graft.Completion CO 2 angiography demonstrated good flow into the celiac artery, SMA, and renal arteries with no endoleak (Fig 2, F).Finally, IVUS confirmed appropriate placement and flaring of all the stents (Fig 3).Overall, the fluoroscopic time was 39.5 minutes, and 0 mL of contrast dye was used.Postoperative day 2 magnetic resonance angiography demonstrated celiac artery, SMA, and bilateral renal artery stent graft patency with no significant endoleaks.Contrast-enhanced ultrasound at 6 months postoperatively showed no evidence of an endoleak with effective aneurysm sac exclusion and normal endograft filling.