Keywords
splenic artery aneurysm - guidewire - embolotherapy - embolic agent
Introduction
Splenic artery aneurysms are among the more frequently diagnosed intra-abdominal aneurysms
and are reported to have an incidence of around 8–50% in patients with raised portal
venous pressure, often being the presenting feature of portal hypertension.[1]
[2] Management options range from medical management to endovascular and surgical treatment.
Here we present a case of Non-cirrhotic portal fibrosis and portal hypertension with
multiple large true aneurysms arising along a dilated and tortuous splenic artery
that required endovascular coiling using guidewires and standard metallic coils in
a two-staged procedure that was followed by surgical aneurysmectomy and splenectomy.
Case Report
A 36-year-old female patient diagnosed with Non-cirrhotic portal fibrosis and portal
hypertension was evaluated with a multi-detector computed tomography (MDCT) angiography
that demonstrated the presence of a dilated and tortuous splenic artery with multiple
large true aneurysms arising from the splenic artery ([Fig. 1]). The spleen was massively enlarged with tortuous portal venous collaterals consistent
with portal hypertension. The patient was initially taken up for splenectomy. During
the surgery, however, the surgeons encountered substantial blood loss during dissection
which was dealt by aneurysmorrhaphy and this prompted a plan for a staged procedure;
embolization of the splenic artery or aneurysms preceding the surgical splenectomy
and aneurysmectomy to mitigate profuse intra-operative blood loss. Blood investigations
revealed a low hemoglobin (6.8 g/dl) for which multiple packed cell units were transfused.
Clinical, hematological and coagulation parameters were within normal limits and the
patient was taken up for splenic artery embolization.
Fig. 1 MDCT angiography in coronal maximum-intensity-projection demonstrating the multiple
splenic artery aneurysms.
The right common femoral artery was punctured using a 18G percutaneous puncture needle
(Cook Medical, Bloomington, IN) and the celiac artery was accessed using a 5F Simmons
catheter (Cook Medical, Bloomington, IN). The subsequent angiogram showed multiple
large aneurysms along the course of the splenic artery, the largest aneurysm and the
most proximal aneurysm of these measuring 65 × 49 mm and 43 × 35 mm in size, respectively.
The splenic artery at the origin from the celiac trunk measured 19mm in diameter with
a distance of 36mm from the origin to the most proximal aneurysm. Following this,
coil embolization was attempted using a 10-mm × 14 cm coil (Nester, Cook Medical,
Bloomington, IN) which immediately dislodged into a distal aneurysmal sac due to the
wide aneurysmal neck and the intrinsic high flow state that was prevalent. Two other
unsuccessful attempts were made to coil embolise the proximal splenic artery with
12-mm × 14 cm coils (Nester, Cook Medical, Bloomington, IN) both of which had similarly
dislodged into the distal splenic artery immediately on deployment. Another attempt
was made to embolize the proximal splenic artery by anchoring a coil into the left
gastric artery and deploying into the splenic artery. This again was in vain as the
high flow state prevented it from coiling within the splenic artery. The decision
to embolize the proximal splenic artery using an Amplatzer vascular plug (AVP) was
initially considered however since the intention of endovascular therapy was pre-operative
cessation of splenic artery flow to aid surgical ligation, the additional expense
that would entail in the likelihood of AVP dislodgement was taken into consideration
and hence embolization using AVP was not entertained.
As the usage of coils as embolic agents ended in repeated failures a plan was made
to pack the proximal aneurysmal sac with guidewires. This was first attempted using
a 0.035” guidewire (Radifocus, Terumo Corporation, Tokyo, Japan) which was cut according
to the length based on the size of the proximal aneurysms and distance from splenic
artery to the most proximal aneurysm. Utmost care was taken to ensure the hydrophilic
coating was not sheared from the nitinol core so as to prevent the inner core from
being exposed. The process was repeated several times, each time cut at a shorter
length than the last until the aneurysmal sac was sufficiently packed. After which
the angiogram showed persistent filling of the aneurysmal sac, however with reduced
flow. Once the proximal aneurysmal sac was packed, multiple coils were nestled into
the scaffolding provided by the matrix of guidewires and this was performed using
six 12-mm × 14 cm, three 10-mm × 14 cm (Nester, Cook Medical, Bloomington, IN) and
three 8-mm × 5 cm MReye (Cook Medical, Bloomington, IN) coils which were progressively
packed one after the other in to the aneurysmal sac and the proximal splenic artery
till a sufficient degree of stasis was achieved meanwhile preserving the right hepatic
artery which was seen to arise from the celiac artery ([Figs. 2] and [3]).
Fig. 2 (A) and (B) Proximal aneurysmal sac with the coiled guidewires within (white arrows). Trailing end of an unsuccessful coiling attempt by anchoring into the left gastric
artery (black arrows). Persistent filling of the aneurysmal sac (
asterisks
) despite multiple guidewires and coils within (C) prompting further deployment of coils until stasis was finally achieved (black arrows) without compromising flow into the right hepatic artery (white arrows) (D).
Fig. 3 Pre (A) and post (B) embolization angiograms revealing the multiple aneurysms along the splenic artery
and stasis post embolization. Displaced coils from the initial attempts are seen in
the distal aneurysmal sac (arrowheads).
The patient was then taken up for surgery two days post-embolization as planned. The
splenic artery was clamped at the head of the pancreas and the coils and the guidewires
that were placed in the proximal splenic artery were retrieved. As the distal splenic
artery was adherent to the distal body and tail of the pancreas, they were dissected
together and resected along with the splenic artery aneurysms and the spleen ([Fig. 4]). The post-operative recovery period was uneventful.
Fig. 4 Surgical splenectomy and aneurysmectomy specimens with a trailing end of one of the
guidewires within the proximal aneurysm (white arrow).
Discussion
Splenic artery aneurysms are among the most common intra-abdominal aneurysms after
abdominal aortic and iliac artery aneurysms. Causative factors include multiple pregnancies,
arteriosclerosis, trauma, pancreatitis, liver transplantation and portal hypertension.
Incidence of splenic artery aneurysms in portal hypertension are reported to range
from 8% to as high as 50%.[1] The risk of spontaneous aneurysmal rupture and the mortality rate following rupture
are as high as 10% and 40% respectively and are likely to occur in aneurysms larger
than 2 cm in diameter, pregnancy, pseudoaneurysms and hepatic transplant patients.[1]
[3]
Endovascular management is considered the first line of management and treatment options
include coiling (including detachable coils), glue embolization, stent-graft placement
and vessel occlusion by vascular plugs.[1]
[2]
[4]
[5] Giant aneurysms of the splenic artery are extremely rare with few reported cases
managed by surgery.[1]
[6]
[7] The mortality and morbidity associated with surgical treatment of splenic artery
aneurysms are 1.3% and 9% respectively[3] and hence in the present case due to the blood loss sustained during the initial
surgical attempt the decision was taken to embolize the splenic artery to prevent
catastrophic bleeding during surgery. However, the large aneurysmal dilatation and
the high flow within the proximal splenic artery precluded packing it with coils.
The use of guidewires as a matrix to nestle in coils for embolization have been previously
described in the embolization of giant pulmonary artery aneurysms and visceral arterio-venous
fistulas.[8]
[9] While using the guidewires to pack the aneurysm in our case, initially the decision
was taken to use a long enough segment of the guidewire to allow it to coil within
the sac and provide a scaffolding for subsequent coiling. There is a risk of arterial
wall erosion by the guidewire owing to the stiffness of the inner nitinol core. However,
the use of guidewires with Teflon coating in which the inner mandril can be removed
will help moderate the risk. In the present case, the benefit of decreased blood loss
during the subsequent surgery outweighed this risk since this was a staged procedure
and not an exclusive endovascular therapy.
To conclude this case shows that embolization of large aneurysms with unfavorable
anatomy and high flow states can be accomplished with reasonable efficacy using guidewires.
