Keywords
conformable embolic - embolization
Introduction
Arteriovenous malformation (AVM) is a rare cause of gastrointestinal bleeding (GIB)
and usually results in lower GIB due to its occurrence in the small bowel. It is commonly
treated with surgical resection of the involved bowel segment. Embolization is performed
with liquid embolic materials either preoperatively or as a definitive therapy.[1] Duodenal AVMs are rare and are often associated with hereditary hemorrhagic telangiectasia.[2] Initial diagnosis may be feasible on endoscopy, but angiography is definitive and
allows therapy with embolic materials.[3] We report a case of duodenal AVM that is treated with a conformable embolic material.
Case Report
A 69-year-old woman with systemic sclerosis complicated by esophageal stenosis presented
to the emergency department with acute hematemesis, tachycardia, and hypotension.
She had recently undergone endoscopy with esophageal dilation and cautery for bleeding
AVMs, and was found to have diffuse angioectasia in the distal duodenum and small
bowel. Laboratory values showed a drop in hemoglobin from 10.3 to 9.2 g/dL, and a
computed tomography (CT) scan revealed active extravasation from the duodenum ([Fig. 1]). Emergent endoscopy was performed, and an arterial feeder of the duodenal AVM was
clipped, but the patient experienced persistent bleeding, prompting catheter angiography
to evaluate the need for embolization.
Fig. 1 (A, B) Axial computed tomography image of a 69-year-old woman with systemic sclerosis demonstrates
hyperdense layering of contrast (white arrows) in the proximal D1 and D2 segments of the duodenum, consistent with active gastrointestinal
bleeding secondary to angioectasia. Duodenal arteriovenous malformation (white arrows) is visualized on (C) axial and (D) coronal MIP images (3.8 mm) obtained 3 years prior with no evidence of active extravasation.
MIP, maximal intensity projection.
Digital subtraction angiography (DSA) of the celiac artery and the gastroduodenal
artery demonstrated no active extravasation, pseudoaneurysm, or AVM. DSA of the superior
mesenteric artery (SMA) revealed an actively bleeding AVM in the second portion of
the duodenum fed by the inferior pancreaticoduodenal artery (IPDA; [Fig. 2A]). Super-selective angiography of the IPDA with a microcatheter confirmed the duodenal
AVM with active extravasation ([Fig. 2B]). The microcatheter was advanced to the nidus of the AVM. The nidus and the feeding
artery were embolized with 1 mL of conformable gel embolic material (Obsidio) ([Video 1]). Embolic material distributed into the nidus, proximal venous segment, and the
arterial feeder, leading to complete occlusion of the AVM ([Fig. 2C]). Repeat SMA angiography demonstrated no residual filling of the AVM and no active
extravasation ([Fig. 2D]). The patient remained hemodynamically stable, and she was discharged on postoperative
day 6.
Fig. 2 (A) Superior mesenteric angiogram demonstrating an actively bleeding arteriovenous malformation
(AVM) in the second portion of the duodenum fed by the inferior pancreaticoduodenal
artery (IPDA), with active extravasation at the site of previously placed clips (white arrow). (B) Selective IPDA angiogram, white arrow at the site of clips. (C) Selective embolization of the IPDA with Obsidio (white arrowheads). (D) Postembolization superior mesenteric artery (SMA) angiogram demonstrating no filling
of AVM.
Discussion
Duodenal AVMs are a rare but important cause of GIB. Thus, their management requires
careful consideration of embolic options.[1] While coils are commonly used in the treatment of arterial bleeders and pseudoaneurysms,
their role in AVMs is limited by difficulties in achieving complete occlusion, especially
in small or tortuous vessels. Moreover, coils may not provide the level of precision
and durability required for optimal AVM management.[2]
[4]
For AVMs, where the goal is often not just to control hemorrhage but also to occlude
the nidus without compromising surrounding healthy tissue, liquid embolic materials
offer unique advantages. Liquid embolic materials, such as n-butyl cyanoacrylate (NBCA)
and ethylene vinyl alcohol (EVOH), have been used with success in AVM embolization,
offering superior flow control and the ability to penetrate small, tortuous vessels.
However, these materials can be technically challenging, as they are prone to issues
such as premature polymerization, catheter occlusion, or off-target embolization,
particularly in high-flow systems such as duodenal AVMs.[4]
Obsidio is a newer, conformable embolic material offering advantages over traditional
liquid embolics in AVM treatment. It behaves like a liquid in the microcatheter, becoming
solid-like upon deployment due to shear-thinning properties, allowing for easier flow
under pressure and stable occlusion once released. This unique behavior enables rapid,
stable hemostasis, especially in technically challenging distal vessels.[4] These properties make Obsidio a good choice for complex AVMs, especially when the
nidus is catheterized.
Obsidio offers several advantages over NBCA in embolizing duodenal AVMs, particularly
in smaller, tortuous vessels where NBCA can be difficult to control and carries a
risk of reflux or off-target embolization. Obsidio is a conformable material that
does not stick to the catheter and allows for modified penetration with injection
force, providing more control. However, the Food and Drug Administration (FDA) has
issued a warning about an increased risk of ischemia when using Obsidio for GIB, highlighting
the need for careful patient selection and precise technique.[5] Despite this caution, Obsidio remains a valuable tool for managing AVMs, especially
when distal access is challenging or other embolic agents are less effective.
Conclusion
This case highlights the evolving role of conformable embolic materials like Obsidio
in the management of duodenal AVMs. The ability to achieve rapid and durable hemostasis,
particularly in complex or small vessels, makes Obsidio a valuable option for embolization
in the cases where distal access is difficult or impossible. Compared with traditional
embolic materials such as coils or NBCA, Obsidio offers distinct advantages, particularly
in terms of flow control, precision, and long-term occlusion.
Video 1 Selective embolization of duodenal AVM with conformable gel embolic (Obsidio).
