million units. Scintigraphy was performed continuously throughout. If bleeding was detected , the patient then underwent angiographic evaluation. The provoked bleeding rate in this study was 40%.

If at all possible, these studies are performed elec­tively, and patients are admitted for a procedure. Surgi­

cal consultation is obtained prior to provocation, and blood group and cross matching is performed. Access to the common femoral artery is obtained and an angio­graphiC sheath placed. A Mikaelsson (AngioDynamics Inc, Queensboro , NY) catheter or a Cobra-2 (Angio­

Dynamics Inc, Queensboro, NY) catheter is used for selective sequential catheterization of the celiac, SMA and IMA. Full mesenteric angiography is performed im­

mediately prior to provocation. Scintigraphic studies and clinical information are examined prior to the procedure

in order to assess which vessel is most likely to be responsible for the bleed. If other studies are not direc­tive, we begin with catheterization of the SMA due both to the fact that its blood supply is to the largest area of bowel, and also due to the fact that it supplies the area of bowel most difficult to assess by endoscopy. 15 min­utes after the infusion of 10 mg tPA, 5000U heparin and 25 mg tolazoline, an angiogram is performed of the provoked vessel. If active bleeding is identified, an at­tempt is made to control it with super-selective emboli­zation. If bleeding is not identified, a decision is made either to proceed with further infusion of tPA (we have

safely used up to 50 mg given in 10 mg aliquots) into the same vessel, or proceed to provocation of the second vessel. The catheter is already in position to effect treat­

ment by embolization or vasopressin if necessary, and for this reason, it may prove to have a better safety profile (we have had no complications in 34 patients, to date). Provocative angiography is costly and time con­suming, and selection of patients for the study should be biased towards patients who will clearly benefit from the procedure. Patient selection is one area that needs to be further examined and optimized for the performance of provocative angiography. Our experience suggests that the procedure has an acceptable safety profile.

If these measures fail to identify a bleeding site, the intra-arterial administration of vasopressin should be considered. This is typically administered through a 5 French catheter in the parent vessel (usually SMA) at a rate of 0.2-0.4 units/ min. A usual infusion time is 12 hours, after which the vasopressin in slowly weaned or turned off, then saline is infused over several hours. The patient is then brought back to angiography for a repeat angiogram. If no clinical or angiographic evidence of

bleeding is present, the procedure is terminated. Patients undergoing a vasopressin infusion should be carefully monitored in an intensive care setting. Vasopressin not only has potential local arterial effects that could cause bowel ischemia, but it can also have adverse system cardiac and circulatory effects.

5:10 p.m. Embolization Techniques: Standard and Not So Standard Methods Pranav N. Shah, MD Red Bank Radiology Group Red Bank, N]

Historical Perspectives GI Bleeding embolization evolved as the natural off­shoot of failed medical management, failed endoscopic management, failed surgical management, and failed in­tra-arterial vasopressin infuSion. Autologous clot was first utilized as the cheapest and most simple agent, but because of rapid recanalization (days), its use has essen­tially been abandoned. Over the last decade , there has been a significant advance in embolic agent design, availability, and scope. Although there are numerous agents available, with choice determined by size of ves­sel to be occluded, as well as duration of occlusion, I will mainly discuss today's most commonly used embolic agents for GI Bleeding: Gelfoam, PolyVinyl Alcohol (PVA) , Embospheres and coils/ microcoils.

Goal of Embolization To stop the hemorrhage while preserving normal tissues. Tools:

• Long flexible sheaths with hemostatic valves and distal radio-opaque markers (Cook formable, Cor­dis Brite-Tip, Arrowflex, Terumo Pinnacle)

• Diagnostic catheters (both standard and hydro­philic coated) including Omni , Cobra, Simmons, Levin , Mikaellson , and Berenstein

• Guide wires (standard and hydrophilic) including Bentsen , Rosen, standard J, Amplatz, Glidewire, Roadrunner, 0.018" glidewire, Transcend EX, V18

• Microcatheters such as Tracker, FasTracker, Rene­gade, and Hi-Flo Renegade

Embolic agents: • Temporaly-Gelfoam torpedoes, pledgets, and

slurry (permits recanalization within weeks) • Permanent- PVA, Embospheres and coils (0.035",

0.038")/ microcoils (:S0.018')

General techniques of GI bleeding embolization: • Obtain a thorough diagnostic arteriogram, identify

acute bleeding or extravasation, and then recog­nize the possibility of more than one vessel sup­plying the bleeding point due to the presence of collaterals.

• Secure a stable position within the main parent vessel with a long sheath or guiding catheter to facilitate catheter exchanges with minimal risk of losing access to the vessel.

• Choose embolic agent and embolize. Remember, as with real estate, success may only depend on one factor: LOCATION, LOCATION, LOCATION! Remember, also, to avoid non-target embolization by carefully administering particles or Gelfoam un­der fluoroscopic control and watching for reflux.

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Avoid complete embolization stasis as a final se­lective arteriographic injection may cause reflux of into the parent vessel and subsequent non-target

embolization.

• Final arteriography should include the emboli zed vessel, as well as all vessels that could potentially feed the emboli zed vessel.

For Upper GI Bleeding (proximal to the Ligament of

Treitz): GASTRITIS AND ULCERS are the most common sources, usually from the Left Gastric Artery (LGA) or Gastro-Ouoqenal Artery (GOA). Gelfoam torpedoes, pledgets, and slurry are most commonly used (DO NOT USE POWDER!!!). This is especiillly true when treating

benign sources of bleeding such as trauma or peptiC ulcer disease, where healing of the underlying lesion is

expected, or for temporalY devascularization of sites prior to surgical resection (to minimize blood loss). Coils can also be used to augment the embolization, or for

flow protection prior to particle embolization. PYA par­ticles or Embospheres may be utilized for tumor related bleeding. Note, when using coils, DO NOT EMBOLIZE

THROUGH HYDROPHILIC CATHETERS, because the coils have an increased risk of lodging within this type of catheter. Co-axial microcatheter systems are commonly available (FasTracker, Hi-Flo Renegade), and can be the key to gaining entry into smaller branches.

For Lower GI Bleeding (distal to the Ligament of

Treitz): The most common site is usually from branches of the SMA or IMA. Options include PV A particles, Em­bospheres, Gelfoam, or microcoils. With advent and availability of excellent microcatheter/ wire combina­

tions (i.e., Renegade Hi-Flo catheter with Transcend EX wire) allOWing catheterization of third, fourth, and fifth order branches, microcoils are probably the most logical and preferred agent for Lower GI Bleeding embolization.

General principles of GI bleed embolization:

For upper GI bleed: • If GOA source is found, you must assess Inferior­

Pancreaticoduodenal artery from SMA for addi­tional supply to the bleeding site.

• If LGA source is found, you must assess the Left Hepatic artery, Right Hepatic artery, Right and Left Castro-epiploic arteries, and Short Gastric (from Splenic artery) arteries for additional supply to the

bleeding site. • If pseudoaneurysm is found, you must embolize

proximal and distal to the pseudoaneurysm to

achieve success. • If no angiographic source is found , you may con­

sider empirically embolizing LGA if known Mal­lory-Weiss tear, fundal bleed, or distal esophageal

bleed is suspected. • If no angiographic source is found , you may con­

sider empirically embolizing GOA if bleeding ulcer

is suspected.

For lower GI bleed-assess the following areas of anas­tomoses when active bleeding is found:

• Inferior Pancreatico-Ouodenal artery (first branch of SMA) with GOA

• Middle Colic artery with Left and Right Colic arter­ies

• Left Colic artery (from Inferior Mesenteric artery) with left branch of Middle Colic artery

• Superior Hemorhoidal arteries (from IMA) with Internal Iliac artery branches

Remember the follOWing general rules for Lower GI Bleed Embolization:

• Avoid proximal vessel embolization. • Be as selective as possible to the level of the

arcade . • Do NOT use small PYA or Embosphere particles

(i.e., less than 350 microns) or PYA powder, be­cause of the high risk of bowel infarction.

• Do NOT use Vasopressin after embolization due to high risk of infarction.

• You may need to use vasodilators to treat arlerial spasm

Finally, remember. . ... Eventual success of your emboli­zation may still require adjunctive endoscopy, mec,Jical management, coagulation parameter optimization, trans­fUSion, or surgery.

5:30 p.m. Complications and Uncommon Situations Frank A. Morello, Jr., MD University of Texas MD Anderson Cancer Center Houston, TX. With today's technology and techniques, complications during diagnostic arteriography should be rare. In addi­tion, most patients who are aClltely bleeding are sicle and have velY little tolerance for error. Puncture site compli­cations, catheter-induced arterial injury, and contrast! medication reactions should be minimal and dealt with accordingly.

Similarly, many errors in diagnosis can be avoided by following the advice given in the sections above. It has been already mentioned that these studies are difficult to perform and interpret. VelY experienced angiographers have agonized over not finding a bleeding site they knew was there based on ancillary imaging and clinical presentation, only to go back to. the hospital in the middle of the night with their colleagues to review the images again. EvelY study will not be perfect, and some­times the answer may not be found. Surgery is always an option, but has a high mortality in this clinical situation. Every effort should be made to perform a patient and complete study so if surgery is the next step, as much information can be given to the surgeon so as to mini­mize surgical morbidity.

Most complications during these studies revolve around the administration of chemical or particulate em­bolic agent. As mentioned before, patients having vaso-