Inferior Mesenteric Artery Aneurysm: Report of a Case

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• Abstract
• Introduction
• Case Report
• Discussion
• References
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Abstract 

We present a case of a 42-year-old man with severe abdominal pain and a pulsatile mass in the epigastric area. On CT-Scan there was no aortic ectasia, but a large mass in front of the aorta, on his left side. The diagnosis of the CT-scan was a pseudo-aneurysm of the inferior mesenteric artery. Angio-MR and angiography confirmed the presence of a true aneurysm of the inferior mesenteric artery. The patient had a successful operation with lateral clamping of the aorta and ligation of the aneurysm.

Keywords: Inferior mesenteric artery aneurysm, Splanchnic arterial aneurysm, Abdominal

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Introduction 

Aneurysms of the inferior mesenteric artery (IMA) are very rare, representing about 0.5% of all visceral arterial aneurysms.¹ Most of them are asymptomatic, but when they present as a rupture, a high mortality is associated. The most usual location of splanchnic arterial aneurysm is splenic artery (60%), followed by hepatic artery (20%), superior mesenteric artery (5.5%) and celiac trunk (4%).² We report a case of IMA aneurysm in a patient with pancreatic disease.

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Case Report 

We report the case of a 42-year-old man who was sent to the emergency department by his general physician for severe abdominal pain. This pain started two days before and gradually increased. He had no fever on admission, neither the days before. He was a smoker for more than 20 years (more than 20 cigarettes a day), alcohol use with previously pancreatitis but no other medical problem. On the physical examination, a pulsatile mass was find on the epigastric area, he had normal peripheral artery pulses. On the laboratory findings, he had pancreatitis with 340UI/L of amylase and 378UI/L of lipase. On CT-Scan we find an 8cm mass on the left side of the aorta. This was first described as a pseudo-aneurysm of the inferior mesenteric artery. There were signs of chronic pancreatitis in the form of pseudo-cystes in the pancreas. The angio-MR and the aortography confirmed the presence of a true aneurysm of the IMA. The patient underwent midline laparotomy with a transperitoneal approach to the abdominal aorta. The peroperative findings revealed a 8.2cm IMA aneurysm. Ten minutes of lateral aortic clamping were necessary in order to perform the exclusion of the IMA aneurysm. The IMA was ligated. The IMA aneurysm was then completely resected, and no IMA reimplantation was necessary, as there was a good collateralization of the IMA and the splanchnic arteries. Microscopic examination of the resected IMA aneurysm revealed its degenerative origin, with fragmentation of the media. The postoperative period was uneventful (Figure 1, Figure 2).

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• Figure 1 

  (a) Angio-MR confirmed the presence of an aneurysm of the inferior mesenteric artery. (b) Angiography confirmed the presence of an aneurysm of the inferior mesenteric artery.

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• Figure 2 

  Midline laparotomy with lateral clamping of the aorta and exclusion of the aneurysm of the inferior mesenteric artery.

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Discussion 

Aneurysms of the IMA are very rare, but according to Saliou et al., they are probably more common than is reflected in the literature.³ Most of them are asymptomatic until rupture. The incidence of rupture was between 20% and 50%, depending on the location of the aneurysm.⁴ We found 33 cases of IMA aneurysms including our own. There were six women and 27 men. Patient age ranged from 9 to 84 years. The aneurysms were mostly degenerative in origin, including our patient's. The other aetiologies were: mycotic due to endocarditis, Takayasu's disease, a dissecting haematoma, a false iatrogenic postoperative aneurysm and polyarteritis nodosa.⁵ In most of the reported cases as well as in our own, the location of the aneurysm was in the proximal trunk of the artery. The majority of the IMA was asymptomatic, but in this case the aneurysm was symptomatic. The most common circumstances leading to diagnosis in the asymptomatic cases were a pulsatile abdominal mass. In other cases, the aneurysm presented with lower back or abdominal pain . In the most severe cases, the aneurysm presented with haemorrhagic shock due to rupture. Standard abdominal ultrasound, computed tomography and angiography can be helpful in the diagnosis.

Treatment of IMA aneurysm included resection, ligation with exclusion, resection and reimplantation into the aorta, hypogastric artery or prosthesis, and resection with bypass reconstruction. There was also in selected cases an option for endovascular treatment, in this case the endovascular option was consider not feasible because of the emergency of the operation and also the absence of suitable material at this moment. IMA aneurysm is a very rare condition that can be difficult to diagnose. Resection, with or without reconstruction, is the treatment of choice for its treatment.

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References 

1. Stanley JC, Thompson NW, Fry WJ. Splanchnic artery aneurys. Arch Surg. 1970;101:689–697
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2. Tulsyan N, Kashyap VS, Greenberg RK, Sarac TP, Clair DG, Pierce G, et al. The endovascular management of visceral artery aneurysms and pseudoaneurysms. J Vasc Surg. 2007;45(2):276–283
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3. Saliou C, Cron J, Julia P, Fabiani JN. Aneurysm of the inferior mesenteric artery: case report and review of the literature. Eur J Vasc Endovasc Surg. 1997;14:71–74
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4. Ruiz-Tovar J, Martinez-Molina E, Morales V, Sanjuanbenito A, Lobo E. Evolution of the therapeutic approach of visceral artery aneurysms. Scand J Surg. 2007;96:308–313
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