AJR 2000; 175:1649-1651
© American Roentgen Ray Society
CT-Guided Thrombin Injection into Aneurysm Sac in a Patient with Endoleak After Endovascular Abdominal Aortic Aneurysm Repair
J. C. van den Berg1,
R. P. Tutein Nolthenius2,
J. W. B. M. Casparie1 and
F. L. Moll2
1
Department of Radiology, St. Antonius Hospital, Koekoekslaan 1, 3435 CM
Nieuwegein, The Netherlands.
2
Department of Surgery, St. Antonius Hospital, 3435 CM Nieuwegein, The
Netherlands.
Received January 17, 2000;
accepted after revision May 16, 2000.
Address correspondence to J. C. van den Berg.
Introduction
Endovascular treatment is becoming a valuable alternative to open surgical
repair of aneurysms of the infrarenal abdominal aorta. With the advent of this
new technique, however, specific complications related to the procedure, such
as graft—limb thrombosis and persistent perigraft flow, also can
arise.
For the treatment of these complications several radiologic options exist.
We have successfully used CT-guided injection of thrombin directly into the
aneurysm sac as a treatment of persistent endoleak.
Case Report
A 71-year-old man was treated for an infrarenal abdominal aortic aneurysm
with an AneuRx bifurcated stent-graft (Medtronic AVE; Santa Rosa, CA). Routine
follow-up (that consists of color duplex sonography at 6 weeks, 6 months, and
1 year and contrast-enhanced helical CT at 3 months and 1 year) revealed a
small endoleak 3 months after initial successful implantation, probably
originating from persistent flow through lumbar arteries
(Fig. 1A). The patient was
followed closely with CT every 3 months.
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Fig. 1A. —71-year-old man after endovascular treatment with stent-graft
for infrarenal abdominal aortic aneurysm. Contrast-enhanced CT scan of aorta
with patient in supine position shows endoleak posterior to endograft
(large arrow) and, to lesser extent, ventrally (small
arrow).
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One year after the initial stent-graft placement, growth of the aneurysm
sac was seen, and diagnostic angiography was performed
(Fig. 1B). Selective
catheterization of the superior mesenteric artery, including prolonged imaging
to search for collateral filling from the superior mesenteric artery to the
inferior mesenteric artery, did not show an endoleak. Selective injection of
contrast material into the right hypogastric artery confirmed the presence of
an endoleak originating from patent lumbar arteries.
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Fig. 1B. —71-year-old man after endovascular treatment with stent-graft
for infrarenal abdominal aortic aneurysm. Arteriogram shows filling of lumbar
arteries (small arrows) after nonselective contrast injection into
infrarenal aorta. Note small blush of contrast material within aneurysm sac
(large arrow). R = right.
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High-selective catheterization of the iliolumbar artery was performed and
revealed a vast network of collaterals adjacent to the aneurysm sac and
enhancement of the endoleak (Fig.
1C). Using a coaxial microcatheter technique, we found that it was
technically impossible to reach the origin of the lumbar artery involved. It
was decided that after obtaining informed consent from the patient, treatment
would consist of a thrombin injection into the aneurysm sac. The patient was
placed in a prone position, and a scout CT scan was obtained after IV
administration of contrast medium. After local anesthesia was administered, a
CT-guided puncture with a coaxial needle system consisting of an 18- and
21-gauge needle was performed. The site of maximal contrast enhancement of the
endoleak was punctured successfully
(Fig.1D). The patient was
transported to the angiography suite, and pressure measurements were
performed. A pulsatile pressure varying between 70 and 80 mm Hg was noted.
Subsequently, contrast material was injected, and filling of the aneurysm sac
(partially thrombosed) and, surprisingly, filling of the inferior mesenteric
artery were seen (Fig. 1E).
After flushing the artery with saline, we slowly injected 1 mL of thrombin
(500 IU/mL, thrombin component of Tissucol Duo 500; Immuno, Vienna, Austria)
at a low flow rate (as estimated by prior contrast injection) to avoid
inadvertent injection into side branches.
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Fig. 1C. —71-year-old man after endovascular treatment with stent-graft
for infrarenal abdominal aortic aneurysm. Arteriogram reveals injection
through microcatheter positioned in right iliolumbar artery with network of
collaterals (large arrows) surrounding aneurysm sac. Contrast
material within lumbar artery is also seen (small arrow). Blush
within aneurysm sac is not seen because of dilution with blood originating
from other collaterals. R = right.
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Fig. 1D. —71-year-old man after endovascular treatment with stent-graft
for infrarenal abdominal aortic aneurysm. CT scan obtained with patient in
prone position shows proper placement of coaxial needle system in aneurysm
sac. R = right.
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Fig. 1E. —71-year-old man after endovascular treatment with stent-graft
for infrarenal abdominal aortic aneurysm. Angiogram shows injection of
contrast agent (patient in prone position) through 21-gauge needle filling
aneurysm sac (large white arrow), inferior mesenteric artery
(small white arrow), and distal end of Riolan's arch (black
arrow) before embolization.
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Afterwards the needle was flushed with a small amount of saline. Pressure
in the aneurysm sac dropped to 10 mm Hg, and pulsatility was absent. The
postprocedural course was uneventful, and no complications occurred. CT and
duplex sonography at 3 days and 3 months showed no evidence of endoleak, and
at 3 months growth of the aneurysm was arrested
(Fig. 1F).
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Fig. 1F. —71-year-old man after endovascular treatment with stent-graft
for infrarenal abdominal aortic aneurysm. CT scan obtained 3 months after
thrombin injection shows no evidence of endoleak.
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Discussion
The endovascular treatment of abdominal aortic aneurysms has evolved
rapidly over the last decade. With the introduction of this kind of repair,
special demands are made on the interventional radiologist. Besides the
preoperative workup (including calibrated angiography and helical
contrast-enhanced CT) that is needed for proper patient selection and
endograft sizing, follow-up after endovascular repair is also mandatory
[1]. Screening after surgery
includes color duplex sonography (either unenhanced or enhanced with IV
contrast material) and helical CT. Both modalities are used for the detection
of aneurysm growth and the presence of endoleaks
[1,
2].
An "endoleak" is defined as the persistence of blood flow
outside the graft lumen but within the aneurysm sac or adjacent vessels in
which the graft is deployed [3,
4]. Endoleaks can be divided
according to the time of onset (acute, persistent, and late). A more commonly
used classification is according to the anatomic location
[3]. In this classification,
type I is graft-related (leakage at the proximal or distal attachment site).
Type II is defined as retrograde flow from collateral branches like the
inferior mesenteric artery and the lumbar arteries. Type III is related to
fabric tear, inadequate seal, or disconnection of a modular graft system.
Finally, graft fabric porosity is categorized as type IV. Because of the
presence of an endoleak, the aneurysm sac will be exposed to arterial pressure
(endotension), just as in our patient, and the risk of rupture of the aneurysm
will exist [1,
3].
When an increase of the diameter of the aneurysm sac is seen during
follow-up, treatment is mandatory. In the presence of an anastomotic-type
endoleak (types I and III), treatment consists of an additional extension cuff
placement (a feature unique to modular stent-graft systems). Endoleaks caused
by branch-to-branch flow (type II) are generally treated by coil embolization
of the branches involved with a coaxial microcatheter technique
[5,
6]. However, it is not always
technically possible to reach the origin of the side branches at the level of
the wall of the aneurysm sac. Coil placement at a site distant from the
aneurysm will have no effect or insufficient effect, because of the presence
of a vast network of collaterals
(Fig.1C) that will continue to
pressurize the aneurysm sac.
We describe a new method for the treatment of persistent endoleaks, using
thrombin injected with CT-guidance. Several studies have reported the
successful use of sonographically guided injection of thrombin in false
aneurysms of the common femoral artery and brachial artery after
catheterization [7,
8]. An advantage of the latter
sonographically guided technique described by Kang et al.
[7] is the possibility of
monitoring the progress of the thrombotic process induced by thrombin
injection on a real-time basis. In this way inadvertent injection into side
branches or peripheral embolization can be avoided.
With the patient in a prone position and with the needle in place (as in
our patient), adequate sonographic visualization of the aorta and depiction of
the injection of thrombin is technically not possible. Ideally, adding a small
amount of contrast material to the thrombin solution could help fluoroscopical
visualization of inadvertent injection of thrombin into the feeding vessels.
Although iodinated contrast material and thrombin show no direct interaction,
iodine inhibits the polymerization process of the fibrin network (personal
communication, Immuno).
Therefore, in our patient, the theoretic drawback of the inability to
assess the clotting effect was overcome by slow administration of a small
volume of contrast material to evaluate filling of collaterals before thrombin
injection. A relatively small amount of thrombin (500 IU) injected in our
patient appeared to work well. The treatment of femoral pseudoaneurysms
usually requires 1000-1500 IU of thrombin
[7], but in patients with these
pseudoaneurysms, generally a larger volume has to be thrombosed (as compared
with the smaller patent channels within the aneurysm sac). Because of the
inhibitory action of contrast material on the polymerization of fibrin, no
angiographic control was made, and the drop in pressure within the aneurysm
sac was considered indicative of proper sealing of the endoleak.
The result in our patient indicates that this way of treating endoleaks is
feasible, and the potential risk of colonic ischemia can be avoided with slow
low-volume injections. However, more experience is needed to evaluate the
potential benefit of this procedure.
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Introduction
Case Report
