Recent advances in endovascular techniques for management of acute nonvariceal upper gastrointestinal bleeding Romaric Loffroy Basem A. Abualsaud MingDe Lin Pramod P. Rao Abstract Over the past two decades, transcatheter arterial embolization has become the first-line therapy

for the management of upper gastrointestinal bleeding that is refractory to endoscopic

hemostasis. Advances in catheter-based techniques and newer embolic agents, as well as

recognition of the effectiveness of minimally invasive treatment options, have expanded the role

of interventional radiology in the management of hemorrhage for a variety of indications, such as

peptic ulcer bleeding, malignant disease, hemorrhagic Dieulafoy lesions and iatrogenic or trauma

bleeding. Transcatheter interventions include the following: selective embolization of the feeding

artery, sandwich coil occlusion of the gastroduodenal artery, blind or empiric embolization of the

supposed bleeding vessel based on endoscopic findings and coil pseudoaneurysm or aneurysm

embolization by three-dimensional sac packing with preservation of the parent artery.

Transcatheter embolization is a fast, safe and effective, minimally invasive alternative to surgery

when endoscopic treatment fails to control bleeding from the upper gastrointestinal tract. This

article reviews the various transcatheter endovascular techniques and devices that are used in a

variety of clinical scenarios for the management of hemorrhagic gastrointestinal emergencies.

Keywords Upper gastrointestinal bleeding; Endoscopy; Angiography; Embolization; Surgery

Introduction Upper gastrointestinal bleeding (UGIB) is defined as originating in the distal esophagus, stomach

and duodenum (proximal to the ligament of Treitz). The most common cause of nonvariceal

UGIB is peptic ulcer disease (PUD). Other less common causes include benign and malignant

tumors, ischemia, gastritis, arteriovenous malformations such as Dieulafoy lesions, Mallory-

Weiss tears, trauma and iatrogenic causes[1,2]. Effective treatment requires timely and accurate

diagnosis (location and etiology) and, unlike lower gastrointestinal bleeds, most patients have

undergone endoscopic examination and treatment prior to their referral to interventional

radiology. Of the small group of patients who fail endoscopic therapy, some are treated

surgically[3] but, increasingly, the majority are referred for embolotherapy[4]. Transcatheter

arterial embolization (TAE) has been performed for at least two decades and has been shown to

be effective at controlling hemorrhage and decreasing mortality[5-10]. Embolization techniques

have evolved with the use of microcatheters and new embolic agents. This review presents the

clinical evaluation and causative mechanisms of hemorrhagic upper gastrointestinal emergencies.

It also discusses the advances in endovascular embolization in their management, including

embolic agents, therapeutic techniques, results and limitations.

Indications Indications that require angiogram and embolization are described below. Several population-

based and prospective studies support PUD being the most common cause of acute UGIB[11].

PUD refers to either gastric or duodenal ulcers but under a broad heading of “ulcers” some

investigators also include esophageal ulcers. Approximately 50% of all cases of acute UGIB are

attributed to PUD[11].

Another recently reported trend in acute UGIB involves cyclooxygenase-2 inhibitors.

Cyclooxygenase-2 inhibitors, known for their decreased gastrointestinal toxicity, are extensively

used for both their anti-inflammatory and analgesic properties. This class of anti-inflammatory

drugs is associated with both decreased endoscopic lesions and episodes of UGIB when

compared with their nonselective nonsteroidal anti-inflammatory drug counterparts[12,13].

Population-based studies evidence suggests that the introduction of cyclooxygenase-2 inhibitors

may be associated with an overall increased nonsteroidal antiinflammatory drug use and

UGIB[14]. Gastrointestinal hemorrhage can certainly be facilitated when a patient has an

endogenous coagulopathic state or is taking anticoagulation therapy.

Classically, Mallory-Weiss tears are mucosal lacerations at the gastroesophageal junction or in

the cardia of the stomach[15]. These lesions can be associated with repeated retching or vomiting

and are another important cause of nonvariceal UGIB. It is estimated that 5% to 15% of all cases

of acute UGIB are secondary to Mallory-Weiss tears[15,16]. Most bleeding episodes caused by

MalloryWeiss tears are self-limited, requiring no endoscopic hemostasis[17]. Nevertheless, some

cases are severe enough to require blood transfusions or therapeutic interventions such as

endoscopic hemostasis, endovascular embolization or surgery.

Dieulafoy’s lesion is a rare etiology in acute UGIB. Dieulafoy’s lesions are difficult to identify

endoscopically because they often retract. Their histopathological description is a “caliber-

persistent artery” in the submucosal tissue[18]. These lesions are responsible for less than 5% of

all nonvariceal UGIB[18].

Neoplasms, both malignant and benign, are another infrequent cause of non-variceal UGIB,

contributing to less than 5% of all UGIB cases[19]. Although only a small fraction of UGIB is of

neoplastic etiology, this may be the only presenting symptom of a neoplasm, which should be

included in the differential diagnosis[19].

Other rare causes of nonvariceal UGIB should also be considered in any differential diagnosis.

Hemobilia is a rare cause of UGIB that should be considered in the setting of recent

hepatobiliary tree instrumentation, such as with endoscopic retrograde cholangiopancreatography

or laparoscopic cholecystectomy. Bile duct and hepatic artery injuries are possible complications

of these procedures, and patients can ultimately present with signs of UGIB[20]. In patients with

chronic pancreatitis who present with acute UGIB, hemosuccus pancreaticus should also be

excluded. Although it is an uncommon cause of UGIB overall, bleeding in these patients can be

secondary to a pseudoaneurysm (PA) in peripancreatic blood vessels as a complication of

pancreatic pseudocysts[21]. Finally, iatrogenic injuries secondary to biopsies or endoscopic

procedures, such as percutaneous endoscopic gastrostomy tube placement, are also rare but

documented causes of nonvariceal UGIB[22].

Anatomy The vascular supply to the stomach and duodenum is quite rich, with avid redundant supply. This

can make successful embolization more challenging; however, it decreases the incidence of

postembolization ischemia[23]. The likelihood of successful embolization reflects prior

knowledge of the location of the bleed. The left gastric artery (LGA) runs along the lesser curve

of the stomach and supplies the stomach and distal esophagus. The LGA is most often the first

branch of the celiac trunk (90%) but may arise directly from the aorta, as a lienogastric trunk or

hepatogastric trunk[24]. It anastomoses with the right gastric artery (RGA). Small distal branches

anastomose with short gastric arteries (from the splenic artery) and the left inferior phrenic

artery. The RGA most often originates from the proper, left or middle hepatic artery but may also

arise from the gastroduodenal artery (GDA) or the right hepatic artery (RHA). It is typically a

small vessel that runs in the gastrohepatic ligament and supplies the distal lesser curve of the

stomach and the pylorus. The greater curvature of the stomach is supplied by the gastroepiploic

arcade that courses along the greater curvature of the stomach and is supplied by the right

gastroepiploic artery (RGEA), the terminal branch of the GDA and the left gastroepiploic artery,

a branch of the distal splenic artery (SA). A complete arcade (rather than incomplete or weak) is

present in about 65% of patients. The duodenum is supplied by the pancreaticoduodenal arcade, supplied

by superior and inferior, posterior and anterior pancreaticoduodenal arteries, branches of the GDA and

superior mesenteric artery (SMA), respectively. The GDA arises from the common hepatic artery in a

large majority of patients but may also arise from the RHA, a replaced RHA branch of the SMA, or

directly from the celiac axis.

Diagnostic Angiography Preprocedural assessment and patient preparation Patients undergoing a transcatheter procedure for the evaluation and management of hemorrhage

are often poor surgical candidates. They are more often than not hemodynamically unstable and

often have other clinical issues, such as an electrolyte imbalance or a coagulopathy. Whenever

possible, the hemodynamic status of the patient should be stabilized by fluid resuscitation. Any

pertinent laboratory abnormalities should be corrected by the time the patient reaches the

interventional suite. The preprocedural laboratory data should include complete blood count,

renal function and coagulation parameters. Optimal laboratory parameters include a serum

creatinine < 1.5 mg/dL with an estimated glomerular filtration rate > 60, an international

normalized ratio (INR) < 1.5 and a platelet count > 50000/dL. If necessary, blood products such

as fresh frozen plasma, platelets or packed red blood cells should be transfused before the

procedure. They may also be given intra-procedurally. It is also desirable to correct any

coagulopathy before embolization because achieving hemostasis depends on technically

successful embolization as well as the patient’s ability to clot properly. Any history of prior drug

or contrast medium allergies must be documented. Any pertinent prior diagnostic cross-sectional

imaging studies should be reviewed as these may provide valuable information that may direct

and potentially affect the outcome of the intervention. Virtually all patients will also have

undergone upper endoscopy in an attempt to identify and treat the source of bleeding.

Timing of angiographic evaluation The typical candidate patient presents with the following: (1) massive bleeding (requiring

transfusion of at least 4 U of blood/24 h) or hemodynamic instability (hypotension with systolic

pressure < 100 mmHg and heart rate of 100 min or clinical shock secondary to blood loss); (2)

bleeding that has failed to respond to conservative medical therapy, including volume

replacement, antacids, H2receptor blocking agents or proton pump inhibitors; and (3) bleeding

that has failed to respond to at least one, and sometimes two, attempts at endoscopic control[25].

Endoscopy is performed before angiography. Performance of angiography before endoscopy

leads to an unacceptably high frequency of unnecessary angiography. Endoscopic diagnosis and

therapy can render angiography unnecessary. Endoscopy also helps in planning the timing and

approach of angiography. For example, inability to determine the cause of bleeding at endoscopy because

of severe bleeding should prompt urgent angiography. Even endoscopic localization of the bleeding site

without determination of the cause helps guide which artery to cannulate first at angiography[26].

Negative endoscopic information, such as excluding esophageal bleeding, is valuable to the angiographer.

On the other hand, Walsh et al[27] and Loffroy et al[25] found longer time to angiography to be

predictor of early rebleeding after TAE. They concluded that every effort should be made to perform

angiography with embolization early after bleeding onset. Thus, the ability to achieve bleeding control in

critically ill patients seems to depend chiefly on early intervention.

There is much discussion about the necessity of diagnostic studies preceding angiography.

Certainly, endoscopy has a diagnostic and therapeutic role and can completely replace the need

for angiography of the upper gastrointestinal tract in more than 90% of patients[26]. However,

most of the controversy involves the need for nuclear scintigraphy before diagnostic angiography

in the patient with lower gastrointestinal bleeding. Scintigraphy has been notoriously inaccurate

when locating lesions for surgical resection; however, scintigraphy is certainly more sensitive,

requiring reportedly 10-fold less hemorrhage than angiography to achieve a positive

study[28,29]. As an adjunct to angiography, the probability of a positive diagnostic angiogram is

increased by a preceding positive nuclear scintigraphic study. In general, the decision to proceed

directly to angiography without nuclear scintigraphy depends on the clinical situation and the

degree of hemorrhage. The clinical presentation of lower gastrointestinal bleeding may be

episodic or continual. The former ranges from minor episodes that resolve, to chronic

intermittent bleeding, to severe life-threatening hemorrhage. Angiography is warranted in the

latter group and may, with provocation, play a diagnostic role in the second. Usually, nuclear

scintigraphy is recommended before angiography in all cases of episodic bleeding. Angiography

remains the primary diagnostic imaging tool in those patients with continual active hemorrhage,

however, and delaying angiography for scintigraphy is not warranted. Intermittent lower

gastrointestinal hemorrhage deserves special attention. This difficult group of patients often

bleeds, frequently to low hemoglobin and hematocit levels, yet a site cannot be localized.

Bleeding has been successfully provoked using a variable combination of anticoagulants,

vasodilators and fibrinolytics. Wireless capsule endoscopy is now being used as a diagnostic tool

for a variety of gastrointestinal disorders including Crohn’s disease, celiac disease and obscure

gastrointestinal bleeding[30,31]. At the present time, however, it is not a practical modality to

use in acute UGIB.

Finally, the amount of bleeding may affect treatment strategy, continued active bleeding

demands for emergency angiography primarily without pre-procedural testing. Defreyne et

al[32] and Whitaker et al[33] independently indicated that the most important determinant of the

timing of angiography may be the findings of an experienced endoscopist when faced with nontractable

bleeding.

Technique of angiography In the advent of UGI bleeding, the source for hemorrhage is usually identified by endoscopy.

Therefore, angiography is most often performed only as a precursor to TAE based on the

knowledge of the vascular supply to the abnormal area. Diagnostic angiography for UGI

bleeding is straightforward and is centered on the anatomy of the celiac artery and the SMA. A

trans femoral approach is usually used and involves placement of a 5F introducer sheath in the

common femoral artery. A variety of introducers and selective catheters with a smaller caliber

can be used to cannulate the celiac artery and obtain access to the common hepatic artery. For

selective catheterization by way of the femoral route, the most widely used catheters are the

cobra, hook and shortand long-curve sidewinder with a 4F diameter. Once access is secured,

arteriogram is performed to delineate the anatomy. Localization of contrast extravasation into the

bowel lumen is considered as a direct angiographic sign of active GI bleeding. Commonly

encountered indirect angiographic signs of GI bleeding include visualization of an aneurysm, PA

or a submucosal vessel and early venous drainage of angiodysplasia. Other angiographic signs

include neovascularity, mucosal or extramucosal hyperemia, intramural pooling of contrast or

arterial wall abnormalities[34]. Selective catheterization for UGI bleeding includes the celiac and

superior mesenteric arteries. The initial artery catheterized is the one most suspected of bleeding

based on previous imaging or endoscopy, which is, of course, the celiac artery for UGI bleeding.

If no extravasation is seen, then superselective angiography is advised. Depending on endoscopic

findings that offer information on the likely location of the bleeding source, superselective

catheterization of the GDA, LGA or SA may be performed. A microcatheter is always necessary

and recommended for a distal superselective approach to the bleeding vessel so as to avoid the

spasm or occlusion caused by larger 4F or 5F catheters. Longer injection durations or use of

carbon dioxide for contrast medium can also improve sensitivity for small bleeds. In the absence

of hemodynamic instability, computed tomographic angiography is a good and reliable method

to highlight the presence of a bleed in progress and should be performed before any invasive

procedure. Arteriography after superselective cannulation may show extravasation that could

have been missed during contrast injection in the main hepatic artery. When a dual supply of the

bleeding area is suspected, both arterial sources must be embolized to assure that all of the

inflow ceases. This is typically noted in bleeding secondary to an ulcer that erodes into the GDA.

Embolization in this case must start distally to prevent persistent “backdoor” hemorrhage from

the right gastroepiploic and superior pancreaticoduodenal arteries and then proceed to the

proximal side of the erosion.

Provocative angiography We do not believe there is enough data to provide definitive guidelines to perform provocative

mesenteric angiography or pharmacoangiography. Furthermore, this technique is mainly used to

provoke lower GI bleeding, which is more challenging than UGIB. Indeed, contrary to lower GI

bleeding, almost all upper gastrointestinal bleeders have undergone endoscopy in an attempt to

identify, localize and treat the source of bleeding. Several prior studies have shown that empiric

embolization based on endoscopic findings, in the absence of contrast extravasation, can be

performed safely and successfully[25,35,36]. So the absence of angiographic extravasation is

less problematic at the level of the upper gastrointestinal tract and does not prevent from

embolizing the artery that supplies the bleeding site.

However, this technique can be applied in situations where conventional angiography is

nondiagnostic. The addition of pharmacological agents to standard angiographic protocols in

order to increase the diagnostic yield has been reported in case reports and small series.

Provocative mesenteric angiography is the use of thrombolytic, vasodilating and anticoagulation

medications to elicit active bleeding from a source that may have recently ceased hemorrhaging.

Unfortunately, the available literature on this topic is limited. This technique was first reported in

the literature in 1982[37]. Since then, our review of the literature yielded only seven small case

series and two case reports totaling 93 patients[37-45]. Koval et al[38] doubled the rate of

extravasations visualized by angiography from 32% to 65% with the introduction of

pharmacologic angiography. Malden et al[39] and Ryan et al[41] separately showed a provoked

bleeding rate of nearly 40% when previous angiograms had been normal with a minimal

complication rate. Although reasonably successful and without any reported major hemorrhagic

complications, provocative mesenteric angiography is not a commonly used examination. The

precise reasons for this are unknown but likely relate to fear of potential uncontrollable

hemorrhagic complications and lack of familiarity with this procedure by referring clinicians and

interventional radiologists. Both of these are likely a reflection of the sparse data supporting

provocative mesenteric angiography in the literature.

Basically, provocative angiography may increase the diagnostic ability when a normal

angiogram is encountered for nonvariceal UGIB. But several procedure-related factors may

affect the diagnostic yield of provocative studies; these include timing of the procedure, the type

and dosage of provocative medications and the expertise of the operators. The types of

pharmacological provocation reported in the literature have been variable[38-46]. Based on these

data, an idealized protocol could include intra-arterial tolazoline at a dose of 25 mg, intra-arterial

heparin at a dose targeted to double the patient’s baseline activated clotting time and intraarterial

urokinase in aliquots of 250000 U given over 15 min and monitored by diagnostic angiography.

Endpoints are either hemorrhage or a total of 1 000 000 U of urokinase over an interval of

approximately 1 h. However, it should be emphasized that the specific agents and their total doses in

literature are largely arbitrary. Currently, provocative angiography is rarely needed for the diagnosis of GI

bleeding and only limited reports for use in difficult and recurring nonvariceal UGIB have shown to be

beneficial[37,41]. We believe that further prospective studies are required to provide a better

understanding of optimal patient selection and optimal pharmacological provocation. Only with these

kinds of data can provocative GI bleeding studies be appropriately placed in a diagnostic algorithm for

evaluation of patients with GI hemorrhage of obscure origin.

Angiographic Interventions Over the past two decades, angiographic interventions have shifted from playing a purely

diagnostic role to being a major therapeutic option in the management of nonvariceal UGIB.

Transcatheter intervention to control GI bleeding takes two forms: the infusion of a

vasoconstricting medication and the mechanical occlusion of the arterial supply responsible for

the hemorrhage.

Intra-arterial vasopressin infusion Selective infusion of intraarterial vasoconstrictors was one of the first angiographic treatments

for GI bleeding. Vasopressin, a posterior pituitary hormone, elicits smooth muscle contraction in

the mesenteric bed, thereby decreasing the perfusion pressure to the bowel and potentially

resulting in thrombosis of the bleeding site. Vasopressin infusion is easy to perform, most often

by placing a 5F diagnostic catheter into the artery most suspected of bleeding[47]. Vasopressin is

then infused at a rate of 0.2 to 0.4 U/min until successful control of bleeding is observed on

angiography. Then, the mesenteric intraarterial infusion is continued for 12-48 h. Vasopressin

infusion has lost favor for two main reasons: necessary catheterization times can require several

days and, more importantly, the emergence of embolotherapy. For nonvariceal UGIB, the

offending arteries were easily accessible even with large and crude catheter systems and embolic

agents of the past. In addition, given the rich arterial collateral network and proximal site of

embolotherapy, ischemia was not thought to be problematic. Given that embolotherapy replaced

vasopressin infusion early in the treatment of UGIB, there is little recent data on the use of this

technique. In addition, much of the data includes treatment of variceal bleeding. A review of four

of the more recent studies consisting of 267 patients demonstrated an initial 70% to 80% success

rate. They observed approximately 20% rate of rehemorrhage with bleeding refractory to

infusion in up to 40% of patients[48-50]. Failures of vasopressin are thought to be due to the rich

collateral supply to the upper GI tract and the inability to treat potential collateral supply

pathways to the bleeding site, but this is unproven. Finally, the use of vasopressin in the

treatment of nonvariceal UGIB is empiric as there is no substantial data to support its use[51].

Transcatheter selective embolization Standard technique: Because of the high rebleeding rate with infusion therapy, other

angiographic interventions were developed to treat nonvariceal UGIB. As is true of most other

minimally invasive and image-guided interventions, embolotherapy has supplanted surgery in

most centers as the treatment of choice for endoscopy-refractory UGIB. This method is

associated with an initial bleeding control rate of 89%-98%. Clinical success rates range from

52%-98% with most reports showing success rates of 70%-80%[23,46,52,53]. The role of TAE

is to selectively reduce blood supply at the source of bleeding while maintaining enough

collateral blood flow to maintain intestinal viability. Typically, in cases of active hemorrhage

with extravasation of contrast, the bleeding vessel is identified by superselective catheterization

using a microcatheter and embolized with microcoils, particles or glue if arterial flow is not

blocked by the microcatheter (Figure 1). Superselection and embolization of short segments of

visceral arteries can be performed with newer advances in hydrophilic steerable wires,

microcatheters and embolic agents. Coaxial systems allow 2 to 3F catheters to pass through

larger primary catheters to allow access to distal arterial branches[52]. In general, bleeding in the

esophagus and fundus of the stomach is treated by embolization of the LGA (Figure 2). Bleeding

in the body and antrum of the stomach may be controlled by embolization of either the

gastroepiploic, right gastric or gastroduodenal arteries depending on the source of bleeding.

Choice of embolic agent: As is the case with microcatheters and guide wires, embolic agents

too have evolved over time. Many embolization agents have been used successfully: coils,

particulate material such as resorbable gelatin sponge, and nonresorbable polyvinyl alcohol

(PVA) or trisacryl gelatin particles. Liquids such as N-butyl 2-cyanoacrylate (NBCA) glue or

ethylene-vinyl alcohol copolymer (Onyx®, Micro Therapeutics, Inc., Irvine, CA, USA) are less

popularly used[25,46,52,54]. The choice of the best embolic agent is still debatable.

Embolotherapy in these emergency patients has to be fast, easy to perform and effective. Success

is achievable with different materials in experienced interventional radiologist’s hands. Embolic

agents have different constraints depending on the material used.

Coils alone inserted in the GDA or superselectively in the pancreaticoduodenal arteries have

been used with success by several investigators[55-59]. When used in the setting of UGIB, coils

are usually used to occlude or reduce flow into a major vessel, which can also be treated at a

more distal level with a particulate agent (usually gelatin sponge) to aid in hemostasis. The main

advantages of using coils are that they can be delivered in a very precise fashion and carry low

risk of infarction because of the preservation of the distal microvasculature. Coils and microcoils

of different size and length can be used (Figure 3). They may have thrombogenic fibers to

facilitate occlusion of the vessel and they may offer the option of detachability and retrievability.

The main drawback is that they are permanent and may preclude re-accessing the vessel in the future

should it prove necessary. Another disadvantage is that coil application is dependent upon vessel diameter

and intrinsic blood clotting. That is probably why Aina et al[35] and Loffroy et al[25] showed an

association between the use of coils alone and the incidence of bleeding recurrence, especially in patients

with coagulopathy. The advantages of use of PVA or gelatin sponge in association with coils when

choosing a strategy for this subgroup of patients cannot be over stressed.

Gelatin sponge is the main temporary embolic agent used worldwide (Figure 4). It has the

advantage that after resorption, flow will be restored weeks after embolization. Furthermore, it is

readily available, cheap and unlikely to cause ischemia. The disadvantages are that it requires

some time to prepare appropriate-sized particles and the pace of recanalization is unpredictable.

Lang[60] compared several embolic agents in a series of 57 patients. They reported that a high

rate of bleeding recurrence was observed when gelatin sponge was used alone. Similarly,

Encarnacion et al[7] achieved a low success rate (62%) in their series, which included mostly

patients embolized with gelatin sponge alone. These data confirm that the use of gelatin sponge

as the only embolic agent guarantees only short-term results and should probably be avoided.

Particles such as PVA particles and tris-acryl gelatin microspheres may be of advantage when a

flow-directed strategy is favorable, e.g. when diffuse tumor vasculariza

tion is to be excluded from the arterial supply (Figure 5). These agents have been used

successfully in treating gastrointestinal hemorrhage, usually through a microcatheter and at a site

distal to major vessels[60]. Only larger particles (> 500 µm) should be used to decrease the risk

of ischemia from normal tissue devascularization. [25,61-63]

Good results have also been reported with NBCA . Toyoda et al[63] reported that the time

required for TAE using NBCA was significantly lower than for TAE procedures that do not use

NBCA. This is important especially in cases of massive bleeding that require urgent hemostasis.

Indeed, the use of NBCA glue is particularly of interest in hemodynamically unstable patients

and in cases of underlying coagulopathy. A number of institutions have adopted selective

embolization using glue as the only embolic agent as the salvage treatment of choice in UGIB

cases. However, the use of NBCA glue requires training and considerable experience, given the

risk of bowel infarction and glue reflux into other vessels. Reflux of NBCA may also result in its

polymerization to the catheter tip (Figure 6). This bit of NBCA may then be stripped from the

catheter during catheter retraction, resulting in nontarget embolization. The use of a proper

technique, including prompt removal of the catheter after injection as well as aspiration of the

guide catheter after microcatheter removal, can significantly reduce this risk[62]. Another

drawback is the potential risk of bowel stenosis over the long-term. Lang[60] found a 25%

duodenal stenosis rate in a study of 28 patients that were followed up for at least 5 years after

embolization for bleeding duodenal ulcers, even if the link between glue embolization and duodenal

stenosis is difficult to evaluate. Onyx® seems to have great potential as a liquid embolic agent in

embolotherapy of acute arterial gastrointestinal bleeding. Lenhart et al[54] recently reported

their experience with the use of Onyx® in such a setting. Their study represents the first series to

date reporting results on arterial embolotherapy with Onyx® as an embolic agent in the

gastrointestinal tract. The success rate was high (81%) and the complication rate was almost nil.

Onyx® is a new liquid embolic agent composed of ethylene-vinyl alcohol copolymer dissolved

in dimethyl sulphoxide (DMSO), with emerging applications in neurovascular procedures,

predominantly embolization of cerebral aneurysms and arteriovenous malformations[64]. The main

advantages of Onyx® are its nonadhesive properties, high radiopacity and long solidification periods (Figure

7). These properties of Onyx® compared to acrylic glues make the embolization procedure more controllable

and predictable[65]. However, Onyx® has some disadvantageous characteristics. Firstly, DMSO can cause

severe vasospasm if injected rapidly. Secondly, DMSO is volatile and is excreted via respiration and sweat.

This has a typical smell not unlike that of diabetic ketoacidosis and may last a few days. The patient and ward

staff should be warned to expect this. Lastly, the use of Onyx® has cost implications as it is much more

expensive than alternative embolic materials and requires specific DMSO-compatible microcatheters. These

factors explain its restricted use in neuroradiology in most institutions around the world.

Finally, it is not clear if careful selection of the embolic agents according to the bleeding vessel may

play a role in a successful outcome. It would be worth comparing the different embolic agents for

arterial embolotherapy in the gastrointestinal tract in a prospective randomized multi-center trial.

However, data from the literature suggest that coils probably should not be used as the only embolic

agent but rather in association with gelatin sponge, particles or glue for the treatment of

gastroduodenal hemorrhage. Furthermore, surgical glue should probably be used more often,

especially in patients with coagulopathy, because it provides a better and faster hemostasis and does

not cause ischemia. Otherwise, the choice of embolic agent does not seem to affect clinical response

or recurrence rates.

Specific techniques of interest: The upper gastrointestinal tract contains a rich collateral blood

supply that often requires embolization of multiple arteries for successful outcomes. Careful

angiographic assessment of the collateral pathways prior to embolization is essential, especially

in patients with severe atherosclerotic occlusive disease or previous extensive upper

gastrointestinal surgery. If the bleeding is from a duodenal ulcer, the GDA needs to be

catheterized and embolized using the so-called sandwich technique: the catheter is pushed to the

origin of the RGEA and coils are introduced as the catheter is withdrawn to the proximal GDA.

Complete embolization of the GDA, which includes proximal and distal embolization and

exclusion of its two side branches, is the end point in this case (Figure 8A and B)[25,55]. A

selective superior mesenteric arteriogram is performed after embolization to ensure that no

collateral supply to the bleeding site is present. If extravasation is identified, superselective

catheterization of the inferior pancreaticoduodenal artery and the side branch responsible for the

collateral circulation is performed with the microcatheter. Embolization with microcoils of the

bleeding site is performed as distal as possible. This method can also be used at the level of the

SA for treatment of pseudoaneurysmal lesions[21]. As such, the embolization needs to take place

both distal and proximal to the lesion.

If no evidence of bleeding is found on pre-embolization arteriography, then empiric or blind

embolization is advised. Blind or empiric is defined as embolization without angiographic proof

of extravasation and is typically guided by endoscopic information regarding the location of the

bleeding vessel. Coils and gelatin sponge are then often used in such a situation (Figure 8).

Another useful maneuver in this scenario requires clips to be placed around the area of bleeding

during pre-embolization endoscopy. The clips remain in position for several hours and allow for

an educated guess of the location of the culprit vascular branch[56]. If no extravasation is seen

despite the injection of contrast, then the branches terminating to the clip are superselected using

microcatheter techniques and embolized. Arteriography at multiple projections is necessary at

this step to ensure the relation between the clip and the adjacent branches.

Blind embolization is controversial. Because massive bleeding is often intermittent, most groups

have adopted a policy to embolize on the basis of endoscopic findings even in situations where

no extravasation is seen angiographically[36]. In the independent series from Aina et al[35],

Loffroy et al[25] and Padia et al[36] there was no difference in outcome between patients who

underwent blind embolization and those who underwent embolization after a bleeding site had

been demonstrated angiographically. Other researchers have also advocated the practice of

endoscopy-directed blind embolization[57,58]. Based on the findings from the literature and our

own experience, we believe that blind embolization is appropriate. The GDA should be

embolized using the sandwich technique, in which both ends of the artery are filled with coils to

avoid retrograde bleeding from the superior mesenteric circulation. If there is suspicion that smaller

muscular branches terminating to a clip are the culprits, then those should be embolized with any of the

materials available.

PA in peripancreatic or perihepatic blood vessels as a complication of pancreatic pseudocysts or

in the setting of recent hepatobiliary tree instrumentation, respectively, may be responsible for

UGIB. Recently, TAE has generated considerable interest as the first-line therapeutic method for

PAs. The success rate is high, ranging from 62% to 100% in visceral PAs and the morbidity and

mortality rates are low[21]. Most investigators agree that coils are the most appropriate embolic

material[21,66]. However, the traditional technique for PA embolization includes isolating the

lesion by deploying coils in the parent artery, covering both sides of the PA neck to prevent

backbleeding via collaterals (sandwich technique)[21,66]. Embolization of PAs using a

combination of gelatin sponge and coils, NBCA and coils, coils alone or NBCA has also been

described[66,67]. The main drawback of these techniques is the compromised patency of the

parent vessel with potential ischemic complications. Modification of the embolization technique

can help preserve the patency of parent artery while achieving complete embolization.

Superselective arterial embolization is achieved by threeimensional coil-packing of the PA sac

using controlled, detachable microcoils placed in a concentric fashion (Figure 9). This

endovascular technique is generally used for the treatment of intracranial aneurysms[68], often

with the remodeling technique to avoid coil protrusion into the parent artery because of an

unfavorable neck-to-sac [69] ratio . When the PA neck is thin, balloon-remodeling is unnecessary.

However, this method has several potential limitations. The main technical drawback is that the

microcatheter must be placed in the PA sac. Considerable experience is required to pass through

the neck, which is typically slender in peripheral PAs. The other limitation concerns the number

of coils required for complete occlusion of the PA sac, especially those of large size, and

consequently the cost of the procedure. Compared to non-fibered coils, fibered coils have greater

occlusive power, allowing occlusion with a smaller number of coils. Controlled, detachable

fibered microcoils are now commercially available. Packing 80%-90% of the sac usually

provides complete sac exclusion while avoiding complications such as secondary rupture. Few

centers combine the use of detachable microcoils with an injection of Onyx® into the pseudo-

aneurysmal sac to reduce the amount of coils and the risk of over-packing[70]. The coil mesh has

proven to be very effective for capturing Onyx ® and facilitated complete occlusion of a

challenging lesion. However, a limitation to the selection of Onyx® for peripheral indications is

its relatively high cost compared with microcoils, as previously said. In addition, its use may add

to the complexity of embolization procedures because a balloon-assisted remodeling technique is

often necessary.

Conclusion

Nonvariceal UGIB remains a common and often serious clinical dilemma. The past two decades

have seen enormous advances in endovascular device development, including lower-profile

catheter systems and better embolic agents, and treatment of a wide variety of hemorrhagic

conditions. These all have made embolotherapy safer and more efficient and has led to its wider

acceptance. A combination of newer improved techniques, materials and embolic agents has seen

TAE replace surgery to become the gold standard for the treatment of lifethreatening UGIB

refractory to endoscopic hemostasis.

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Figure 1: Arteriogram images of bleeding from a bulbar duodenal ulcer in a 76-year-old man. A,

B: Arteriogram showing contrast medium extravasated from a slender branch of the

gastroduodenal artery into the duodenum (arrows); C, D: After microcatheterization, selective

glue embolization [radiopaque because of associated lipiodol (arrows)] preserving the

gastroduodenal artery ensured control of the bleeding, with no early or late recurrences.

Figure 2: Bleeding dieulafoy lesion in an 87-year-old man. A, B: Extravasation of contrast

medium from the left gastric artery at the celiac trunk and superselective angiography indicates

continuing bleeding (arrows); C: After arterial microcatheterization, bleeding was controlled

after embolization of the left gastric artery using a Glubran/Lipidol mixture (1:3) (arrows).

Figure 3: Detachable metallic coil. This is a vessel-blocking agent which is positioned at the

target site, as opposed to released in the bloodstream.

Figure 4: Preparation of gelatin particles of various sizes by manually cutting gelatin sheets.

When the fundamental principles of embolization are scrupulously followed, absorbable agents

for temporary embolization are effective, safe and cost-effective.

Figure 5: Tris-acryl gelatin microspheres of 500-700 microns in size. Microspheres have two

major advantages: they can be calibrated to ensure accurate targeting and they do not block the

embolization catheter.

Figure 6: Glubran 2®: N-butyl 2-cyanoacrylate + metacrylosulpholane. The main advantage of

cyanoacrylate glue is the lasting nature of the vascular occlusion, compared with particles.

Figure 7: Gelling solution. The only commercially available gelling solution (Onyx®) is

composed of ethylene-vinyl-alcohol copolymer suspended in dimethyl-sulphoxide, with tantalum

to ensure visibility by fluoroscopy.

Figure 8: Typical sandwich embolization in a 75-year-old woman with bleeding from a

postbulbar duodenal ulcer at endoscopy. A: Angiography before embolization, guided by clip

position (arrow): no evidence of active bleeding; B: Coil embolization of the distal and proximal

gastroduodenal artery (with gelatin sponge in the arterial trunk), including the anterior and

posterior superior pancreaticoduodenal arteries and the right gastroepiploic artery, to prevent

retrograde flow (arrows). Bleeding stopped and no ischemic complications were reported.

Figure 9: A 41-year-old woman presented 3 wk after laparoscopic cholecystectomy with right

upper abdominal pain and hemobilia. A: Computed axial tomography scan: round mass within

the gallbladder fossa that shows contrast filling at the arterial phase (arrow), and dilatation of the

bile duct (arrowhead); B: Selective hepatic arteriogram demonstrating pseudoaneurysm of the

cystic artery stump; C: Coil embolization of the aneurysmal sac across the neck using the

packing technique through a microcatheter; D: Control angiography showing complete occlusion

of the false aneurysm and preservation of the main and distal hepatic artery.