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 |
| 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 : 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,
L’Hermine 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.
