Splanchnic Collateral Arterial Aneurysms Associated with Celiac Artery Compression by Median Arcuate Ligament

Abstract

An aneurysm developing in hypertrophied pancreaticoduodenal artery associated with a median arcuate ligament compressing the celiac trunk is a relatively rare entity. We present 2 such cases that we managed recently. One presented with retroperitoneal hemorrhage and the other with signs of intra-abdominal mass effect. In both cases the diagnosis was made on computed tomographic scans and confirmed by diagnostic arteriography. Both cases were successfully treated by embolization of the aneurysms.

VASCULAR DISEASE MANAGEMENT 2012:9(8):E135-E138

Key words: median arcuate ligament, collateral aneurysm, embolization

____________________________________________________

Median arcuate ligament syndrome is a clinical syndrome associated with a median arcuate ligament (MAL) compressing the celiac trunk and resulting in a spectrum of features including mesenteric angina and weight loss. MAL compression alone is a relatively common and under-diagnosed phenomenon, which is usually asymptomatic. With the advent of advanced multidetector CT scanning, it is often detected as an incidental finding.¹ The compression may lead to increased follow through the collateral circulation and rarely this may lead to problems. We present two such cases that we managed by endovascular technique.

Case Report 1. A 56-year-old male patient on irregular treatment for diabetes presented with right lower quadrant abdominal pain, vomiting, and fever of 5 days duration. There was no history of melena. The hematocrit before the procedure was normal and the patient was hemodynamically stable. His general examination was normal. Abdomen examination revealed rebound tenderness in right iliac fossa suggestive of acute appendicitis. The patient was taken for emergency surgery. During surgery, the appendix was found to be normal and there was a large retroperitoneal hematoma extending from the retro-pancreatic area to the pelvis and into small bowel mesentery. CT angiogram done subsequently revealed celiac artery ostial narrowing due to compression by MAL with multiple dilated peripancreatic collaterals along the pancreaticoduodenal arcade. One of the collateral arterial channels showed an irregular fusiform dilatation measuring approximately 9 mm x 7 mm with a surrounding hypodense area consistent with a hematoma.

A digital subtraction angiography was performed by cannulating the superior mesenteric artery (SMA) with a 5 Fr cobra glide catheter and showed the celiac trunk retrogradely filling from the inferior pancreaticoduodenal arcade. The inferior pancreaticoduodenal branch of the SMA was super-selectively cannulated with coaxial placement of a microcatheter (2.7 Fr Progreat, Terumo) through the 5 Fr Cobra glide catheter. The tip of the microcatheter was positioned 2 cm proximal to the aneurysmal site to avoid vasospasm and the aneurysm subsequently embolized with coils (4 mm x 30 mm MWCE 18S 3.0-4-Hilal [Cook] – 2 numbers; 4 mm x 30 mm 0.018” complex helical fibered platinum coil [Boston Scientific] – one number). The gastroduodenal artery was also embolized with Gelfoam slurry and 250 micron PVA particles.

In the post-procedural period he remained hemodynamically stable. However he developed respiratory infection and respiratory failure requiring prolonged ventilation. He continued to be in sepsis and succumbed to a cardiac arrest on the 30th post-procedural day.

Case Report 2. A 54-year-old male patient presented with a history of gradually progressing abdominal pain, vomiting, and distension over a period of 2 months. CT angiogram showed a large bilobed aneurysm measuring approximately 140 mm x 75 mm with a partially thrombosed lumen (Figure 3). The origin of celiac artery was narrowed due to an extrinsic impression by MAL. Selective superior mesenteric angiogram showed hypertrophied pancreaticoduodenal branches, one of them leading to a large pool of contrast, diagnostic of an aneurysm. The inferior pancreaticoduodenal branch was super-selectively cannulated with a coaxial technique using a 5 Fr Simmons 1 reverse curve and a 2.7 Fr microcatheter (Progreat, Terumo), which was advanced to a point 2 cm proximal to the aneurysm. The following coils were delivered in the feeding artery till relative stasis of the contrast column: 0.018-inch coils (6 mm x 60 mm 0.018-inch Complex helical fibered platinum coil [Boston Scientific] – 2 numbers; 5 mm x 50 mm 0.018-inch Complex helical fibered platinum coil [Boston Scientific] – 1 number; 7 mm x 40 mm MWCE 18S 3.0-4-Hilal [Cook] – 1 number; 5 mm x 60 mm MWCE 18S 3.0-4-Hilal [Cook] – 1 number). No particulate embolization was used in this case.

The patient was discharged on the 5th postoperative day following reduction of the clinical symptoms at the time of presentation. The patient also underwent laparotomy and median arcuate ligament division under general anesthesia 3 weeks later. The postoperative recovery was uneventful.

Discussion

The MAL is a fibrous band that connects the left and right diaphragmatic crura across the aortic hiatus (anterior to the aorta), often at the level of the T12/L1 vertebral bodies, although the normal anatomical position is variable. It is often superior to the celiac axis. However, in 5%-24% of individuals, the MAL lies anterior to the celiac axis, causing downward angulation and indentation. This represents an anatomical variant which is non-obstructive by itself.^1,2 It may give a characteristic hook-like configuration with kinking of the proximal artery. However, the condition may progress to MALS. Compression of celiac artery may lead to increased blood flow in the peripancreatic arterial network providing collateral supply for revascularization of the celiac trunk, thus dilating the vascular walls until an aneurysm develops. Similar flow related aneurysms are also described in other parts of the body.

Despite this evidence, the significance of MAL-associated celiac axis compression is a source of some controversy in the literature, particularly given the relatively high incidence of this finding in otherwise asymptomatic individuals4 and also because the success of surgical MAL division has been varied. Collaterals in turn develop from the adjacent arteries like in these 2 cases from the SMA along the pancreaticoduodenal arcade. However, flow related aneurysms secondary to MALS are uncommonly reported in literature. Moreover, rupture of the collateral is a rare event, the incidence of which is not available in the literature.

CT angiogram is a non-invasive procedure and plays an important role in detecting the celiac artery compression at its origin by the MAL as well as identifying the dilated vessels of the pancreaticoduodenal arcade. The source of bleed may also be identified on the CT angiography itself, which helps in planning the embolization. The other causes of visceral aneurysms include atherosclerotic disease, fibromuscular dysplasia, polyarteritis nodosa, mycotic aneurysms, etc. Pseudoaneurysms due to pancreatitis are also common in this area. We presume that in our cases, the aneurysms have developed in the collateral arteries secondary to hemodynamic nature based on the findings on CT, although we do not have pathologic proof for the same.

Surgical division of the median arcuate ligament re-establishes forward unobstructed flow in the celiac trunk, thus reducing the flow pressures in the pancreaticoduodenal arcade.⁷ Reduction in the collateral flow results in significant reduction in the caliber of the collateral arteries. If the collateral arterial aneurysms have grown to a size, which are causing mass effect, the feeding artery ligation or endovascular embolization may be attempted to cause shrinkage of the aneurysm. It is evident that unruptured aneurysms of the pancreaticoduodenal artery need to be treated. However, no studies are available to show whether unruptured aneurysms of the pancreaticoduodenal artery should be treated or left alone.⁷ In the acute setting of aneurysmal rupture, the control of intra-abdominal hemorrhage may be achieved by embolization of the feeding arteries.

Subsequent surgical division of the median arcuate ligament may be required to prevent recurrence of this condition.⁷ We believe that in a patient with asymptomatic collateral aneurysm, it is preferable to treat the underlying cause first, which may result in regression of the aneurysm.

Conclusion

The patients with median arcuate ligament compressing the celiac trunk may rarely present with acute clinical features due to a ruptured aneurysm from a collateral artery. CTA plays an important role in the diagnosis. In cases of ruptured bleeding aneurysms from a collateral artery, transarterial embolization is a vital adjunctive option followed by surgical division of the MAL to prevent recurrence.

References

1. Manghat NE, Mitchell G, Hay CS, Wells IP. The median arcuate ligament syndrome revisited by CT angiography and the use of ECG gating--a single centre case series and literature review. Br J Radiol. 2008;81(969):735-742.
2. Somen S, Sudhakar S, Keshava SN. Celiac axis compression by median arcuate ligament on computed tomography among asymptomatic persons. Indian J Gastroenterol. 2010;29(3):121-123. 
3. Lee AD, Shyamkumar NK, Nayak S, Agarwal S, Perakath B. Collateral artery aneurysm: a unique presentation of thoracic outlet syndrome. Eur J Vasc Endovasc Surg. 2005;29(6):611-612.
4. Levin DC, Baltaxe HA. High incidence of celiac axis narrowing in asymptomatic individuals. Am J Roentgenol Radium Ther Nucl Med. 1972;116(2):426-429.
5. Proud B, Chamberlain I. Aneurysm formation on small pancreatic arteries in association with coeliac axis compression. Ann R Coll Surg Engl. 1978;60(4):294-297.
6. Bellosta R, Luzzani L, Carugati C, Melloni C, Sarcina A. Pancreaticoduodenal artery aneurysms associated with celiac axis occlusion. Ann Vasc Surg. 2005;19(4):534-539.
7. Gouny P, Fukui S, Aymard A, et al. Aneurysm of the gastroduodenal artery associated with stenosis of the superior mesenteric artery. Ann Vasc Surg. 1994;8(3):281-284.

____________________________________________________

Editor’s Note: From the 1Department of Radiology, Christian Medical College and the 2Department of Surgery, Christian Medical College, Vellore, Tamil Nadu, India.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

Manuscript received December 14, 2011,  provisional acceptance given January 5, 2012, final version accepted March 13, 2012.

Address for correspondence: Dr Shyamkumar Nidugala Keshava, Professor, Department of Radiology, Christian Medical College, Vellore, Tamil Nadu, India. Email: aparna_shyam@cmcvellore.ac.in