Asian Cardiovasc Thorac Ann 2002;10:61-63
© 2002 Asia Publishing EXchange Pte Ltd
Superior Mesenteric Artery Aneurysm
Münevver Yüksel, MD,
Fatih Islamo
lu, MD,
Ünal Egeli, MD1,
Hakan Posaciolu, MD,
Rasih Yilmaz, MD2,
Suat Büket, MD
Department of Cardiovascular Surgery
2 Department of General Surgery Ege University Medical Faculty Izmir, Turkey
1 Department of Radiology Letoon Hospital Mula, Turkey
|
|
|
Fatih Islamolu, MD Tel: 90 232 388 2866 Fax: 90 232 339 0002 email: fislamoglu{at}hotmail.com Department of Cardiovascular Surgery, Ege University Medical Faculty, Bornova, Izmir 35100, Turkey.
|
 |
ABSTRACT
|
|---|
A 38-year old woman with mid-epigastric pain, diarrhea, and weight loss, underwent resection of a superior mesenteric artery aneurysm and primary repair of the artery. Pathological examination showed degenerative atherosclerotic changes, marked medial and intimal thickening, and vegetations. Microbiological studies demon-strated Streptococcus viridans as the infecting organism of this mycotic aneurysm. The patient made a good recovery and remained well after 3 years.
|
INTRODUCTION
|
|---|
Superior mesenteric artery (SMA) aneurysm is the 3rd most common splanchnic aneurysm, accounting for 5.5% of splanchnic aneurysms and < 0.5% of all intraabdominal aneurysms.1,2 Although female patients predominated in earlier series, a sex predilection has not yet been confirmed. Mycotic etiology accounts for more than half of these aneurysms, mainly in patients younger than 50 years, as a consequence of subacute bacterial endocarditis. Non-mycotic aneurysms more often affect patients over 60 years old who frequently present with intestinal angina prior to aneurysm rupture.1 There have been few reports of mycotic SMA aneurysms in the last 10 years because of widespread antibiotic usage.3
|
CASE REPORT
|
|---|
A 38-year old woman was admitted to a regional hospital with intermittent mid-epigastric pain that had started 3 months earlier and progressed over the previous month, episodes of diarrhea, and weight loss of over 5 kg in one month. Physical and radiological evaluations were normal but abdominal ultrasonography revealed an aneurysmal mass, 2.5 cm in diameter, originating from the SMA and located posterior to the splenic vein (Figure 1
). This was confirmed by a mesenteric duplex scan, and the patient was referred to our clinic. On examination, she had no epigastric tenderness, abdominal mass, bruit, or organo-megaly, and her peripheral pulses were palpable. Routine laboratory tests were normal. A mesenteric color duplex scan revealed a saccular 28 x 24-mm aneurysm located 2 cm from the origin of the SMA and connected to it via a 6-mm long neck. Aortography and selective mesenteric angiography confirmed a 1.5 x 3 x 4-cm aneurysm of the SMA (Figure 2). There was no other visceral or renal artery abnormality.
View larger version (131K):
[in this window]
[in a new window]
|
Figure 1. Abdominal ultrasonography demonstrating an aneurysmal mass (arrowed), 2.5 cm in diameter, originating from the superior mesenteric artery and located posterior to the splenic vein.
|
|
View larger version (163K):
[in this window]
[in a new window]
|
Figure 2. Aortography showing an aneurysm of the superior mesenteric artery located close to the origin of the artery.
|
|
Surgical repair was performed through a midline trans-peritoneal approach under general anesthesia. The small bowel was placed in an intestinal bag and displaced to the right. The sigmoid and descending colon was mobilized by incising the lateral peritoneal reflection. A plane was developed between the pancreas and Gerota's fascia. The pancreas, spleen, stomach, and descending colon were rotated anteriorly and medially. The spleen and pancreas were protected with moistened pads. A retractor was positioned to hold the mobilized viscera to the right. The peritoneum was reflected from the left crus of the diaphragm, and the left lobe of the liver was freed. The left renal vein crossing the aorta was also mobilized to facilitate exposure of the SMA. There was a firm pulsatile saccular aneurysm of the SMA, which was 4 to 5 cm in diameter and within 1 cm of the SMA origin. There was no hemorrhage. Following circumferential control proximal and distal to the aneurysm, a partially occluding vascular clamp was applied to isolate the aneurysm. On opening the aneurysm, some degenerative changes and small vegetations on the inner wall were observed. The aneurysmal arterial wall was resected completely and the SMA was repaired with a continuous 5/0 polypropylene suture. Samples of the aneurysmal wall and contents were obtained for pathological examination. All specimens were Gram stained and showed degenerative athero-sclerotic changes, marked medial and intimal thickening, and vegetations. Microbiological studies revealed Strepto-coccus viridans as the infecting organism of this mycotic aneurysm. The primary focus could not be detected. Pathological and microbiological evaluation of vascular specimens from the surgical closure site revealed a healthy, normal arterial structure.
The patient's postoperative course was excellent. Gastro-intestinal activity resumed on the 2nd day, and normal oral nutrition began on the 3rd postoperative day. Her epigastric pain and other complaints were relieved completely. She was discharged from the hospital on the 4th postoperative day with 6 weeks of antibiotic (cefazolin) therapy. One month later, she had gained 6 kg in weight. She remained well during 3 years of follow-up. Computed tomographic angiography 3 years after the repair revealed completely normal aortic and mesenteric vasculature.
|
DISCUSSION
|
|---|
Aneurysms affecting the proximal 5 cm of the SMA are usually mycotic and account for 58% to 63% of cases.4 The infection is most commonly caused by nonhemolytic streptococcus, secondary to leftsided endocarditis. Staphylococcal organisms secondary to noncardiac septicemia have been reported.1 Syphilitic aneurysms have not been noted in recent reports. Dissecting aneurysms with medial defects are rare (5%).1,4 Atherosclerosis accounts for 20% of SMA aneurysms. Trauma is a rare cause (1% to 2%). The identification of Streptococcus viridans in this case concurs with recent literature.
The most common symptom is intermittent abdominal discomfort that progresses to persistent severe epigastric pain.1 The mechanism of epigastric pain is interesting. Expansion of the aneurysm with dissection or propagation of an intraluminal thrombus beyond the pancreati-coduodenal and middle colic branches of the SMA leads to occlusion of collateral flow from the celiac and inferior mesenteric arteries. Mobilization of the thrombus and further intermittent thrombus formation due to flow stasis beyond the main thrombus, occludes the collateral circulation and causes intestinal angina.1,2 Thrombotic occlusion of collateral flow was considered the possible mechanism of intestinal angina in our patient. Antemortem diagnosis of an uncomplicated case is unlikely, and most have been diagnosed by radiography for unrelated diseases. Angiography is the preferred mode of diagnosis because it allows assessment of the extent of the aneurysm and aids planning of the operation.1
Because of the high risk of rupture or thrombosis (50%), surgical treatment is reasonable in the absence of complicating factors.1,2,5,6 A third of the reported SMA aneurysms (fewer than 20) have been successfully operated on.7 Surgery may be performed via a transmesenteric technique, but proximal aneurysms require either a left retroperitoneal approach with medial reflection of the colon, pancreas, and spleen, or a transscleral approach.1,2 The usual treatment methods are aneurysmography and ligation. Collateral flow from the inferior pancreati-coduodenal and middle colic arteries improves the outcome, thus temporary SMA occlusion and observation of the small bowel viability is recommended.1 Aneurys-mectomy may be hazardous because of the close proximity of the superior mesenteric vein and pancreas, and serious risk of bleeding from such a high-flow system with good collaterals.1,2 Transcatheter occlusion has proven useful in patients with medial degenerative disease who have substantially higher risks of bleeding and death, and in some saccular aneurysms or pseudoaneurysms with a discrete neck connected to the SMA.2,8
Since the SMA remains critical in chronic mesenteric ischemia, and subsequent procedures may threaten collateral circulation, arterial reconstruction with an interposition graft or aorto-mesenteric bypass has been preferred.2,6 After the operation, if a mycotic aneurysm is suspected, long-term antibiotic therapy must also be added.1 Although prosthetic grafts used to be re-commended to avoid potential kinking of saphenous vein grafts, the high incidence of mycotic etiology increases the risk of graft infection. Therefore, saphenous vein bypass with preservation of graft configuration is favored.1,2 Zimmerman-Klima and colleagues2 showed that passing the saphenous graft superiorly behind the left renal vein before angling anteriorly to anastomose with the SMA was a satisfactory way of avoiding kinking. Aneurysm resection and reconstruction of the SMA by direct anastomosis to the aorta may also be performed.6 In this patient, primary closure of the arterial wall was adequate. When the healthy arterial segments are of adequate size, this technique may be performed safely.
|
REFERENCES
|
|---|
-
Zelenock GB, Stanley JC. Splanchnic artery aneurysms. In: Rutherford RB, Cronenwett JL, Gloviczki P, Johnston KW, Kempczinski RE, Krupski WC, editors. Vascular surgery. Philadelphia: Saunders, 2000:1369–82.
-
Zimmerman-Klima PM, Wixon CL, Bogey WM, Lalikos JF, Powell CS. Considerations in the management of aneurysms of the superior mesenteric artery. Ann Vasc Surg
2000;14:410–4.[Medline]
-
Miani S, Arpesani A, Giorgetti PL, Rampoldi V, Giordanengo F, Ruberti U. Splanchnic artery aneurysms. J Cardiovasc Surg
1993;34:221–8.[Medline]
-
Stanley JC, Messina LM, Zelenock GB. Splanchnic and renal artery aneurysms. In: Moore W, editor. Vascular surgery. Philadelphia: Saunders, 1998:473.
-
Dogan R, Demircin M, Pasaoglu I, Onat DA, Hamaloglu E, Kutluay L. Surgical treatment of splanchnic artery aneurysms secondary to medial degeneration: report of two cases. Thorac Cardiovasc Surg
1995;43:230–3.[Medline]
-
Komori K, Mori E, Yamaoka T, Ohta S, Takeuchi K, Matsumoto T, et al. Successful resection of superior mesenteric artery aneurysm. A case report and review of the literature. J Cardiovasc Surg
2000;41:475–8.[Medline]
-
Friedman SG, Pogo GJ, Moccio CG. Mycotic aneurysm of the superior mesenteric artery. J Vasc Surg
1987;6: 87–90.[Medline]
-
Baker KS, Tisnado J, Cho SR, Beachley MC. Splanchnic artery aneurysms and pseudoaneurysms: transcatheter embolization. Radiology
1987;163:135–9.[Abstract/Free Full Text]
TOP
ABSTRACT
INTRODUCTION
