VASCULAR COMPLICATIONS OF PANCREATITIS : RADIOLOGICAL DIAGNOSIS AND TREATMENT

 

 

Sundeep J Punamiya
Associate Consultant and Head of Department, Vascular and Interventional Radiology, Bombay Hospital, Mumbai.

INTRODUCTION

Involvement of the blood vessels around the pancreas is a frequently occurring event in pancreatitis, seen in at least 10% of the patients suffering from the disease. [1] There are many mechanisms by which the pancreatic and peripancreatic vessels can get involved. The proteolytic enzymes released during the episode of pancreatitis can directly erode the numerous arteries in and around the pancreas, resulting in haemorrhage or formation of a pseudoaneurysm. Alternatively, the inflammatory mass may compress or thrombose the adjacent splenic or superior mesenteric vein. [2]

Arterial complications

The splenic artery, because of its contiguity with the pancreas, is the vessel most commonly involved in pancreatitis. However, virtually all of the pancreatic and peripancreatic vessels can be affected. The gastroduodenal and pancreatico-duodenal arteries are frequently involved, while the left gastric, hepatic and small intra-pancreatic branches are less often implicated. Pancreatic enzymes can produce enzymatic necrosis of the arterial wall, resulting in free haemorrhage or formation of a pseudoaneurysm. The pseudoaneurysm may develop within a pancreatic pseudocyst, or in some cases, the pseudoaneurysm may rupture into the adjacent pseudocyst; in either case the haemorrhage will be confined to the pseudocyst cavity. Once formed, the pseudoaneurysm has a tendency to enlarge and ultimately ruptures into the upper gastrointestinal tract, colon, abdominal cavity, or rarely, the pancreatic duct. [1] Rupture into the aorta, portal vein and venous tributaries have also been reported.

 

Encasement of major arteries is also frequently seen in pancreatic disease. However, thrombosis of these arteries is not a prominent feature. When it occurs, arterial thrombosis could lead to splenic or bowel infarction.

Venous complications

Unlike arterial thrombosis, thrombosis of the splenic vein is much more common, being reported in [8] .5-45% of patients with pancreatitis. [3] Thrombosis involving the portal and superior mesenteric veins is rare and if present, should raise the suspicion of either a septic stage of severe necrotising pancreatitis or a pancreatic head malignancy.

CLINICAL PRESENTATION AND DIAGNOSIS

Early recognition of bleeding in patients with pancreatitis is essential for successful management and reduction of mortality. The presenting features are usually a combination of gastrointestinal bleeding, vague recurrent upper abdominal pain, pulsatile abdominal lump and splenomegaly. Pulsatility or rapid enlargement of a pre-existing pseudocyst should alert the clinician about bleeding into the pseudocyst. If the patient has undergone an abdominal surgery, such as necrosectomy, the bleeding may appear within the abdominal drains. Unusually, the patient may present with blood loss anaemia due to long-standing occult bleeding from a pseudoaneurysm into the gastrointestinal tract. the patient manifests as a GI bleed, endoscopy is often the first investigation to rule out bleeding from other sources e.g. peptic ulcer disease, gastritis, Mallory-Weiss tears and varices. Occasionally it may permit diagnosis of pancreatic bleeding (haemosuccus pancreaticus) and rarely may reveal the site of the erosion of the pseudocyst directly into the GI tract.

 

Ultrasonography is generally asked for when a pre-existing pseudocyst has rapidly enlarged in size, suggesting bleeding into the cavity. If the enlargement is indeed due to haemorrhage into the pseudocyst, the USG confirms rapid enlargement of the cystic mass, with a sudden change in its internal echogenicity. [4] When these collections are studied after a week, the cystic mass shows solid tissue or septations. [5] Occasionally it is impossible to distinguish between pseudoaneurysms and pseudocysts on routine USG examination. With the advent of Doppler, however, it is now possible to detect blood flow within the haemorrhagic pseudocyst.

Computed tomography (CT) produces excellent opacification of the arteries and veins surrounding the pancreas and is an invaluable modality for identifying these vascular complications. [6] , [7] The finding of a focal collection of fluid with increased attenuation (more than 30 HU) or an interim increase in the attenuation values of the fluid within a previously demonstrated pseudocyst, is diagnostic of acute bleeding into the pseudocyst. A dynamic, contrast-enhanced spiral CT scan can diagnose pseudoaneurysm by demonstrating contrast pooling in the collection (Figs. 1A, 1B). CT is also the procedure of choice in diagnosing splenic vein thrombosis (Fig. 2).

Fig 1A Fig 1B Fig 1C
Fig 1A Fig 1B Fig 1C
Plain CT of the abdomen revealing a collection in the pancreatic bed After injecting contrast, there is opacification of a pseudoaneurysm within the collection. Cleliac angiogram confirming large pseudoaneurysm arising from the splenic artery
A 56 year old female , presented with persistent pain in the left hypochondrium 6 months after initial episode of pancreatitis.

 

Angiography provides the most detailed evaluation of vascular involvement and may diagnose the site and source of bleeding, indicated by erosive arterial changes or pseudoaneurysm formation (Fig. 1C). On occasion, there may be multiple small pseudoaneurysms or encasement of the intra-pancreatic arteries (Fig. 3A). Rarely, frank extravasation of contrast from the artery or pseudoaneurysm is seen (Fig. 3B). In addition, it can evaluate the portal venous system, for detection of splenic vein thrombosis and confirmation of associated generalised portal hypertension due to liver disease. No intervention, be it surgical or percutaneous, is carried out without angiographic mapping of the arterial patho-anatomy.

 

MANAGEMENT

Haemorrhage from pancreatic and peripancreatic vessels is severe and, until recently, had been associated with mortality rates approaching and exceeding 50%, primarily because of delayed diagnosis and extreme conservative treatment. [2] , [8] Prompt diagnosis and an aggressive interventional approach has helped in reducing the mortality. Surgical management has been the mainstay in treating these vascular complications. However, the past decade or so has seen a rapid acceptance of angiographic techniques to control the bleed in these patients, with a success rate ranging from 78-100%. [1] , [9-14] Angiographic control involves placement of embolic material, e.g. steel coils, selectively into the artery that is either bleeding or fostering the pseudoaneurysm.

Fig 2
Fig 2 : 46 year old male, 4 weeks after an attack of pancreatitis. Contrast enhanced CT revealing an acute panmcreatic collection, with thrombosis of the underlying splenic vein

The success rates of transcatheter embolisation have varied over the years, with the initial reports citing a fair number of rebleeds. As the past decade progressed, the success rates began to show a great deal of improvement, being attributed to betterment of catheter and embolic material technology and to the improvement in technical expertise. The earliest problems associated with transcatheter control of bleeding in pancreatitis was inability to reach the small and tortuous target vessels with the large calibre catheters that were available. Micro-catheters, primarily designed for use for embolisation in the cerebral vessels, were then adapted for visceral arteries. It was with the aid of these catheters that even the small intra pancreatic arteries could be catheterised and embolic material delivered .

 

Along with this development, came an understanding about the techniques involved in successful embolisation in pancreatitis. Due to thegood collateral circulation around the pancreas, it is essential to occlude the artery proximal and distal to the arterial pathology, failing which the artery can refill and the bleeding will not cease. If the vessel is severely involved and can be closed only upstream or downstream, one could use additional liquid embolic material such as glue for effective embolisation. [15] Embolisation can be a time-consuming process, especially if there are a number of efferent arteries originating from the pseudoaneurysm or there are many collateral circulations coming from the adjacent arteries. The expertise of the interventional radiologist plays an important role in suspecting this potential problem and addressing it immediately.

 

CONCLUSION

Vascular complications of pancreatitis although uncommon, are usually life-threatening. Clinical suspicion, corroborated with judicious use of imaging, can bring about a prompt diagnosis and prevent morbidity that is usually associated with these complications. Immediate efficacy of arterial embolisation is undeniable and the procedure is rapidly being accepted as the first line of treatment, wherever the expertise of the interventional radiologist is available.

 

 

REFERENCES

1.Boudghene, LíHermine C, Bigot JM. Arterial complications of pancreatitis: diagnostic and therapeutic aspects in 104 cases. J Vasc Interv Radiol 1993; 4 : 551-558.

2.Stanley JC, Frey CF, Miller TR, et al. Major arterial haemorrhage: a complication of pancreatic pseudocysts and chronic pancreatitis. Arch Surg 1976; 111 : 435-440.

3.Bernades P, Baetz A, Levy P, et al. Splenic and portal venous obstruction in chronic pancreatitis: a prospective longitudinal study of a medical-surgical series of 266 patients. Dig Dis Sci 1992; 37 : 340-346.

4.Vujic I, Seymour EQ, Meredith HC. Vascular complications associated with sonographically demonstrated cystic epigastric lesions: an important indication for angiography. Cardiovasc Intervent Radiol 1980; 3 : 75.

5.Hashimoto BE, Laing FC, Jeffrey RB Jr, Federle MP. Haemorrhagic pancreatic collections examined by ultrasound. Radiology 1984; 150 : 803.

6.Burke JW, Erickson SJ, Kellum CD, et al. Pseudoaneurysms complicating pancreatitis: detection by CT. Radiology 1986; 161 : 447-450.

7.Vujic I. Vascular complications of pancreatitis. Radiol Clin North Am 1989;27:81-91.

8.Stabile BE, Wilson SE, Debas HT. Reduced mortality from bleeding pseudocysts and pseudoaneurysms caused by pancreatitis. Arch Surg 1983; 118 : 45.

9.Vujic I, Anderson BL, Stanley JH, et al. Pancreatic and peripancreatic vessels: embolisation for control of bleeding in pancreatitis. Radiology 1984; 150 : 51.

10.Mauro MA, Jaques P. Transcatheter management of pseudoaneurysms complicating pancreatitis. J Vasc Interv Radiol 1191; 2 : 527-532.

11.Savastano S, Feltrin GP, Antonio T, et al. Arterial complications of pancreatitis: diagnostic and therapeutic role of radiology. Pancreas 1993; 8 : 687-692.

12.Sawlani V, Phadke RV, Bailajl SS, et al. Arterial complications of pancreatitis and their radiological management. Australas Radiol 1996; 40 : 381-386.

13.Gambiez LP, Ernst OJ, Merlier OA, et al. Arterial embolisation for bleeding pseudocysts complicating chronic pancreatitis. Arch Surg 1997; 132 : 1016-1021.

14.Golzarian J, Nicaise N, Deviere J, et al. Transcatheter embolisation of pseudoaneurysms complicating pancreatitis. Cardiovasc Intervent Radiol 1997; 20 : 435-440.

15.Yamakado K, Nakatsuka A, Tanaka N, et al. Transcatheter arterial embolisation of ruptured pseudoaneurysms with coils and n-butyl cyanoacrylate. J Vasc Interv Radiol 2000; 11 : 68-72.

 

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