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Embolization
Brandt C. Wible, MD; T. Gregory Walker, MD, FSIR
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KEY FACTS

  • Terminology

    • Preprocedure

      • Outcomes

        TERMINOLOGY

        • Definitions

          • Embolization: Therapeutic technique using direct/transcatheter introduction of intravascular agent for hemorrhage control/devascularization/occlusion
            • Various available agents
              • Subclassified as temporary and permanent agents
          • Temporary embolic agents
            • Gelatin sponge
              • Inexpensive, readily available, rapid preparation and effect
              • May be prepared as single torpedo or slurry
              • Recanalization of embolized vessel is unpredictable, usually occurring within weeks to months
              • Consider use for rapid embolization of arterial hemorrhage, combine/sandwich with coil embolization, temporarily occlude shunting prior to definitive treatment, occlude percutaneous transhepatic access, or when permanent embolization not ideal
                • Not ideal for small vessel embolization
              • Gelfoam
                • Sheet form; can cut into pledgets/create slurry
              • Surgifoam
                • Sheet form similar to Gelfoam
                • Powder form (40- to 60-μm particle diameter) causes distal occlusion; possible ischemia/infarction
            • Autologous clot
              • Delivery of patient's thrombosed blood products
              • Short effective duration (hours)
          • Permanent embolic agents
            • Coils: Mechanical metal occluding device; assumes coiled configuration upon exiting catheter, blocks vessel with fibers, swelling hydrogel; various sizes, configurations, and shapes (e.g., straight, helical, tornado-tapered, 2D, or 3D)
              • Consider coil use when catheter can be advanced to targeted vessel
              • Bare metal coils: Stop blood flow mechanically
                • Stainless steel: Bioinert, radiopaque, relatively stiff
                • Platinum: Compliant, pack well, microcatheter delivery possible
                • Nitinol: Highly flexible, shape memory
              • Bioactive coils: Surface modifications added to coil to aid thrombogenicity
                • Fibered coils
                • Polymer-coated coils
                • Hydrogel-coated coils
                • Protein-coated coils
              • Pushable 0.035" or 0.018" coils: Inexpensive, straightforward delivery
                • May be advanced and deployed through catheter with "coil-pusher" wire or careful (semiforceful) injection with 1- to 3-cc syringe of saline
                • May not be possible to remove/snare if malpositioned
              • Examples
                • Azur HydroCoil
                • Nester, Hilal, and Tornado coils
                • VortX embolization coils
              • Detachable 0.035" or 0.018" coils: May be retrieved if in suboptimal location/configuration
                • Consider detachable coil use in critical vessels, high-flow shunts, or areas where nontarget embolization could inadvertently occur (e.g., gastroduodenal artery)
                • Multiple detachment designs exist (e.g., mechanical, electrical)
                • Retrieval not always possible if coil fully deployed or too much time elapsed
              • Examples
                • Azur HydroCoil
                • Concerto
                • DeltaPaq, DeltaWind
                • Interlock, Matrix
                • Ruby
              • Neurointerventional coils
                • Specifically designed for intracranial usage
              • Examples
                • Axium
                • Microvention
                • Orbit Galaxy
                • Target
            • Particles: Micron-sized solids; lodge at precapillary/capillary level; occlude vessels/devascularize tissue
              • Consider use within end-arteries when distal arteriole/organ embolization desired
              • Consider avoiding particles in cases of vascular shunting or collateral vasculature; concerns include nontarget embolization
              • Polyvinyl alcohol (PVA): Nonspherical, irregular sizes
                • Occlude more proximal than vs. similar-sized spherical particle (bead)
                • Can clump, resulting in proximal vessel/catheter occlusion
              • Examples
                • Contour PVA
                • PVA foam embolization particles
                • Contour SE microspheres; calibrated PVA microspheres (teardrop shape)
                • Bead Block; calibrated PVA hydrospheres
              • Spherical: Consistent diameter particles vs. PVA
                • May lead to significant embolization and subsequent ischemia of distal tissue/organ
                • Increased cost vs. PVA
                • Slightly compressible during delivery
              • Examples
                • Embospheres; calibrated acrylic polymer microspheres
                • Embozene microspheres; hydrogel microsphere with Polyzene-F coating
            • Plug occluding device: Woven expandable nitinol (thrombosis) ± membrane (mechanical occlusion)
              • Mechanically occludes target vessel in similar manner to coil embolization
              • Allows precise positioning, short landing zone, rapid occlusion
              • Recommended to oversize 30% beyond target vessel diameter
              • Less trackable through tortuous vessels vs. coils
              • Examples
                • Amplatzer Plug
                • Caterpillar
                • Micro Vascular Plug
            • Liquids: Variety of nonsolid embolic
              • Consider use for specific clinical situations: Complex embolic target requiring embolic penetration beyond catheter into nidus [arteriovenous malformation (AVM)], desire to solidify target vessel (intracranial aneurysm), oncologic use (hepatocellular carcinoma), nonvascular target (biliary leak)
              • Sufficient training and well-developed understanding of each specific liquid embolic's properties and risks is necessary prior to use
              • Delivery of liquid embolics often require advanced training and experience and can be challenging to properly deploy
              • Examples
              • Ethanol: 96-98%, immediately denatures cellular proteins/causes small vessel thrombosis
                • Can be used to ablate whole organ (e.g., kidney)
                • Also useful as sclerosant
                • Extremely painful during delivery; consider general anesthesia
                • Not visible during delivery (unless mixed 4:1 with Lipiodol); calculate desired volume of ethanol using dilute contrast
                • Caution: Ensure no shunting is present
              • Lipiodol: Ethiodized oil; iodine-containing poppy seed oil
                • Used in conventional transarterial chemoembolization where it acts as fluoroscopically visible chemotherapeutic delivery agent and transient arterial embolic
                • Can occlude lymphatic leaks (50-75%) during lymphangiogram
                • Added to other embolics during delivery (e.g., ethanol, "glue")
                • Dissolves soft plastics (e.g., catheter hub, syringe, 3-way stopcock)
              • N-butyl cyanoacrylate (n-BCA) Trufill
                • Solidifies on contact with ionic medium (e.g., blood)
                • Liquid "glue" polymer is mixed with Lipiodol immediately prior to delivery
                • Ratio with more Lipiodol (5:1) slows rate of glue polymerization/solidification; ratio with less Lipiodol (2:1) increases rate of polymerization/solidification
                • Nonionic preparation of table, gloves, catheters, syringes vital
                • All equipment must be meticulously flushed with nonionic solutions (e.g., D₅W)
                • "Glue" is deployed between nonionic solution
                • Small volumes of n-BCA:Lipiodol necessary
                • Caution: Catheter can become "glued" to vessel
                • Has nonvascular applications, since occlusion does not require platelets/coagulants
              • Onyx
                • Ethylene vinyl alcohol copolymer dissolved in dimethyl sulfoxide (DMSO)
                • Radiopaque-suspended, micronized tantalum powder added for increased visibility; tantalum may become visible through skin if treating superficial vascular malformations
                • Precipitates from outside in on contact with aqueous solution as DMSO dissipates
                • Forms "foam" with lava-like flow pattern
                • Nonadhesive; catheter very unlikely to stick to vessel during delivery; allows slower, more deliberate injection vs. n-BCA "glue"
            • Thrombin solutions
              • Rapidly converts fibrin to fibrinogen, activates coagulation cascade; causes thrombotic occlusion of target
              • Extremely small volumes (0.2-0.5 cc) typically necessary
              • Severe potential effects of nontarget embolization; Doppler distal pulse during delivery in extremity
              • Aneurysm occlusion off-label use
              • Caution: Do not use if patient had prior allergic reaction to thrombin
              • Examples of topical thrombin
                • Surgiflo
                • Floseal
            • Sclerosing agents
              • Detergents: Causing vessel occlusion via inflammation/thrombosis
                • Consider use in varicose veins, venous malformations, pelvic congestion syndrome, balloon-occluded retrograde transvenous obliteration
                • Can use as liquid, or mix with air (or CO₂) to form foam
                • Advantage of foam: Increased contact with wall, requires decreased sclerosing agent
              • Examples
                • Ethanolamine oleate iopamidol (Ethamolin): Widely used in Japan
                • Polidocanol: Widely used in Europe
                • Sodium tetradecyl sulfate-STS (Sotradecol): Mild sclerosant; typically 3% STS (available in 2-mL vials) is mixed with air/CO₂ (3 mL air: 2 mL STS: Add 1 mL Lipiodol for visualization as needed)
                • Sodium morrhuate (Scleromate): Fallen out of favor
              • Examples of other sclerosants
                • Ethanol: Immediate protein denaturation and cell death
                • Boiling contrast: Not often used due to patient pain, operator risk
              • Lymphocele sclerotherapy
                • Doxycycline: Intracavitary injection effective for treatment of lymphatic malformations; inexpensive, widely available
                • Tetracycline, bleomycin, talc and fibrin glue intracavitary injection have also been described
            • Oncologic agents
              • Drug-eluting beads: Chemotherapeutics are bound to spheres ionically (irinotecan) or osmotically (doxorubicin) and delivered to tumor where chemotherapeutics release from beads, resulting in significantly higher concentrations at tumor bed than can be achieved via IV delivery
              • Examples
                • LC Beads (DC Beads in Europe): Blue tint, sizes include 100-300 µm, 300-500 µm, and 500-700 µm
                • QuadraSphere: Spheres enlarge over time: 30-60 µm, 50-100 µm, 100-150 µm, and 150-200 µm
              • Radioactive particles: β-emitting particle, Y-90 embedded on microspheres
                • Selective internal radiation therapy (SIRT)
              • Examples
                • SIR-Spheres; resin microspheres, increased particles per dose
                • TheraSpheres; glass microspheres with increased activity per particle
            • Stents: Used in association with embolization coils
              • Stent-assisted coil embolization: Noncovered stent placed across wide neck aneurysm
                • Coils introduced through stent interstices into aneurysm/pseudoaneurysm using microcatheter

        PREPROCEDURE

        • Indications

          • Contraindications

            • Getting Started

              PROCEDURE

              • Patient Position/Location

                • Procedure Steps

                  • Alternative Procedures/Therapies

                    POST PROCEDURE

                    • Things to Do

                      • Things to Avoid

                        OUTCOMES

                        • Problems

                          • Complications

                            • Expected Outcome

                              Selected References

                              1. Doucet J et al: The feasibility of degradable glass microspheres as transient embolic medical devices. J Biomater Appl. 35(6):615-32, 2021
                              2. Altun I et al: Blood-derived biomaterial for catheter-directed arterial embolization. Adv Mater. 32(52):e2005603, 2020
                              3. Hu J et al: Advances in biomaterials and technologies for vascular embolization. Adv Mater. 31(33):e1901071, 2019
                              4. Horbach SE et al: Sclerotherapy for low-flow vascular malformations of the head and neck: a systematic review of sclerosing agents. J Plast Reconstr Aesthet Surg. 69(3):295-304, 2016
                              5. Spiotta AM et al: Comparison of techniques for stent assisted coil embolization of aneurysms. J Neurointerv Surg. 4(5):339-44, 2012
                              6. Etezadi V et al: Endovascular treatment of visceral and renal artery aneurysms. J Vasc Interv Radiol. 22(9):1246-53, 2011
                              7. Zhu X et al: Utility of the Amplatzer Vascular Plug in splenic artery embolization: a comparison study with conventional coil technique. Cardiovasc Intervent Radiol. 34(3):522-31, 2011
                              8. Duffy DM: Sclerosants: a comparative review. Dermatol Surg. 36 Suppl 2:1010-25, 2010
                              9. Lee BB et al: Management of arteriovenous malformations: a multidisciplinary approach. J Vasc Surg. 39(3):590-600, 2004
                              10. de Giovanni JV: The use of Amplatzer devices to occlude vascular fistulae. J Interv Cardiol. 14(1):45-8, 2001
                              11. Jackson JE et al: Treatment of high-flow vascular malformations by venous embolization aided by flow occlusion techniques. Cardiovasc Intervent Radiol. 19(5):323-8, 1996
                              12. Jander HP et al: Transcatheter gelfoam embolization in abdominal, retroperitoneal, and pelvic hemorrhage. Radiology. 136(2):337-44, 1980
                              Related Anatomy
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                              Related Differential Diagnoses
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                              References
                              Tables

                              Tables

                              KEY FACTS

                              • Terminology

                                • Preprocedure

                                  • Outcomes

                                    TERMINOLOGY

                                    • Definitions

                                      • Embolization: Therapeutic technique using direct/transcatheter introduction of intravascular agent for hemorrhage control/devascularization/occlusion
                                        • Various available agents
                                          • Subclassified as temporary and permanent agents
                                      • Temporary embolic agents
                                        • Gelatin sponge
                                          • Inexpensive, readily available, rapid preparation and effect
                                          • May be prepared as single torpedo or slurry
                                          • Recanalization of embolized vessel is unpredictable, usually occurring within weeks to months
                                          • Consider use for rapid embolization of arterial hemorrhage, combine/sandwich with coil embolization, temporarily occlude shunting prior to definitive treatment, occlude percutaneous transhepatic access, or when permanent embolization not ideal
                                            • Not ideal for small vessel embolization
                                          • Gelfoam
                                            • Sheet form; can cut into pledgets/create slurry
                                          • Surgifoam
                                            • Sheet form similar to Gelfoam
                                            • Powder form (40- to 60-μm particle diameter) causes distal occlusion; possible ischemia/infarction
                                        • Autologous clot
                                          • Delivery of patient's thrombosed blood products
                                          • Short effective duration (hours)
                                      • Permanent embolic agents
                                        • Coils: Mechanical metal occluding device; assumes coiled configuration upon exiting catheter, blocks vessel with fibers, swelling hydrogel; various sizes, configurations, and shapes (e.g., straight, helical, tornado-tapered, 2D, or 3D)
                                          • Consider coil use when catheter can be advanced to targeted vessel
                                          • Bare metal coils: Stop blood flow mechanically
                                            • Stainless steel: Bioinert, radiopaque, relatively stiff
                                            • Platinum: Compliant, pack well, microcatheter delivery possible
                                            • Nitinol: Highly flexible, shape memory
                                          • Bioactive coils: Surface modifications added to coil to aid thrombogenicity
                                            • Fibered coils
                                            • Polymer-coated coils
                                            • Hydrogel-coated coils
                                            • Protein-coated coils
                                          • Pushable 0.035" or 0.018" coils: Inexpensive, straightforward delivery
                                            • May be advanced and deployed through catheter with "coil-pusher" wire or careful (semiforceful) injection with 1- to 3-cc syringe of saline
                                            • May not be possible to remove/snare if malpositioned
                                          • Examples
                                            • Azur HydroCoil
                                            • Nester, Hilal, and Tornado coils
                                            • VortX embolization coils
                                          • Detachable 0.035" or 0.018" coils: May be retrieved if in suboptimal location/configuration
                                            • Consider detachable coil use in critical vessels, high-flow shunts, or areas where nontarget embolization could inadvertently occur (e.g., gastroduodenal artery)
                                            • Multiple detachment designs exist (e.g., mechanical, electrical)
                                            • Retrieval not always possible if coil fully deployed or too much time elapsed
                                          • Examples
                                            • Azur HydroCoil
                                            • Concerto
                                            • DeltaPaq, DeltaWind
                                            • Interlock, Matrix
                                            • Ruby
                                          • Neurointerventional coils
                                            • Specifically designed for intracranial usage
                                          • Examples
                                            • Axium
                                            • Microvention
                                            • Orbit Galaxy
                                            • Target
                                        • Particles: Micron-sized solids; lodge at precapillary/capillary level; occlude vessels/devascularize tissue
                                          • Consider use within end-arteries when distal arteriole/organ embolization desired
                                          • Consider avoiding particles in cases of vascular shunting or collateral vasculature; concerns include nontarget embolization
                                          • Polyvinyl alcohol (PVA): Nonspherical, irregular sizes
                                            • Occlude more proximal than vs. similar-sized spherical particle (bead)
                                            • Can clump, resulting in proximal vessel/catheter occlusion
                                          • Examples
                                            • Contour PVA
                                            • PVA foam embolization particles
                                            • Contour SE microspheres; calibrated PVA microspheres (teardrop shape)
                                            • Bead Block; calibrated PVA hydrospheres
                                          • Spherical: Consistent diameter particles vs. PVA
                                            • May lead to significant embolization and subsequent ischemia of distal tissue/organ
                                            • Increased cost vs. PVA
                                            • Slightly compressible during delivery
                                          • Examples
                                            • Embospheres; calibrated acrylic polymer microspheres
                                            • Embozene microspheres; hydrogel microsphere with Polyzene-F coating
                                        • Plug occluding device: Woven expandable nitinol (thrombosis) ± membrane (mechanical occlusion)
                                          • Mechanically occludes target vessel in similar manner to coil embolization
                                          • Allows precise positioning, short landing zone, rapid occlusion
                                          • Recommended to oversize 30% beyond target vessel diameter
                                          • Less trackable through tortuous vessels vs. coils
                                          • Examples
                                            • Amplatzer Plug
                                            • Caterpillar
                                            • Micro Vascular Plug
                                        • Liquids: Variety of nonsolid embolic
                                          • Consider use for specific clinical situations: Complex embolic target requiring embolic penetration beyond catheter into nidus [arteriovenous malformation (AVM)], desire to solidify target vessel (intracranial aneurysm), oncologic use (hepatocellular carcinoma), nonvascular target (biliary leak)
                                          • Sufficient training and well-developed understanding of each specific liquid embolic's properties and risks is necessary prior to use
                                          • Delivery of liquid embolics often require advanced training and experience and can be challenging to properly deploy
                                          • Examples
                                          • Ethanol: 96-98%, immediately denatures cellular proteins/causes small vessel thrombosis
                                            • Can be used to ablate whole organ (e.g., kidney)
                                            • Also useful as sclerosant
                                            • Extremely painful during delivery; consider general anesthesia
                                            • Not visible during delivery (unless mixed 4:1 with Lipiodol); calculate desired volume of ethanol using dilute contrast
                                            • Caution: Ensure no shunting is present
                                          • Lipiodol: Ethiodized oil; iodine-containing poppy seed oil
                                            • Used in conventional transarterial chemoembolization where it acts as fluoroscopically visible chemotherapeutic delivery agent and transient arterial embolic
                                            • Can occlude lymphatic leaks (50-75%) during lymphangiogram
                                            • Added to other embolics during delivery (e.g., ethanol, "glue")
                                            • Dissolves soft plastics (e.g., catheter hub, syringe, 3-way stopcock)
                                          • N-butyl cyanoacrylate (n-BCA) Trufill
                                            • Solidifies on contact with ionic medium (e.g., blood)
                                            • Liquid "glue" polymer is mixed with Lipiodol immediately prior to delivery
                                            • Ratio with more Lipiodol (5:1) slows rate of glue polymerization/solidification; ratio with less Lipiodol (2:1) increases rate of polymerization/solidification
                                            • Nonionic preparation of table, gloves, catheters, syringes vital
                                            • All equipment must be meticulously flushed with nonionic solutions (e.g., D₅W)
                                            • "Glue" is deployed between nonionic solution
                                            • Small volumes of n-BCA:Lipiodol necessary
                                            • Caution: Catheter can become "glued" to vessel
                                            • Has nonvascular applications, since occlusion does not require platelets/coagulants
                                          • Onyx
                                            • Ethylene vinyl alcohol copolymer dissolved in dimethyl sulfoxide (DMSO)
                                            • Radiopaque-suspended, micronized tantalum powder added for increased visibility; tantalum may become visible through skin if treating superficial vascular malformations
                                            • Precipitates from outside in on contact with aqueous solution as DMSO dissipates
                                            • Forms "foam" with lava-like flow pattern
                                            • Nonadhesive; catheter very unlikely to stick to vessel during delivery; allows slower, more deliberate injection vs. n-BCA "glue"
                                        • Thrombin solutions
                                          • Rapidly converts fibrin to fibrinogen, activates coagulation cascade; causes thrombotic occlusion of target
                                          • Extremely small volumes (0.2-0.5 cc) typically necessary
                                          • Severe potential effects of nontarget embolization; Doppler distal pulse during delivery in extremity
                                          • Aneurysm occlusion off-label use
                                          • Caution: Do not use if patient had prior allergic reaction to thrombin
                                          • Examples of topical thrombin
                                            • Surgiflo
                                            • Floseal
                                        • Sclerosing agents
                                          • Detergents: Causing vessel occlusion via inflammation/thrombosis
                                            • Consider use in varicose veins, venous malformations, pelvic congestion syndrome, balloon-occluded retrograde transvenous obliteration
                                            • Can use as liquid, or mix with air (or CO₂) to form foam
                                            • Advantage of foam: Increased contact with wall, requires decreased sclerosing agent
                                          • Examples
                                            • Ethanolamine oleate iopamidol (Ethamolin): Widely used in Japan
                                            • Polidocanol: Widely used in Europe
                                            • Sodium tetradecyl sulfate-STS (Sotradecol): Mild sclerosant; typically 3% STS (available in 2-mL vials) is mixed with air/CO₂ (3 mL air: 2 mL STS: Add 1 mL Lipiodol for visualization as needed)
                                            • Sodium morrhuate (Scleromate): Fallen out of favor
                                          • Examples of other sclerosants
                                            • Ethanol: Immediate protein denaturation and cell death
                                            • Boiling contrast: Not often used due to patient pain, operator risk
                                          • Lymphocele sclerotherapy
                                            • Doxycycline: Intracavitary injection effective for treatment of lymphatic malformations; inexpensive, widely available
                                            • Tetracycline, bleomycin, talc and fibrin glue intracavitary injection have also been described
                                        • Oncologic agents
                                          • Drug-eluting beads: Chemotherapeutics are bound to spheres ionically (irinotecan) or osmotically (doxorubicin) and delivered to tumor where chemotherapeutics release from beads, resulting in significantly higher concentrations at tumor bed than can be achieved via IV delivery
                                          • Examples
                                            • LC Beads (DC Beads in Europe): Blue tint, sizes include 100-300 µm, 300-500 µm, and 500-700 µm
                                            • QuadraSphere: Spheres enlarge over time: 30-60 µm, 50-100 µm, 100-150 µm, and 150-200 µm
                                          • Radioactive particles: β-emitting particle, Y-90 embedded on microspheres
                                            • Selective internal radiation therapy (SIRT)
                                          • Examples
                                            • SIR-Spheres; resin microspheres, increased particles per dose
                                            • TheraSpheres; glass microspheres with increased activity per particle
                                        • Stents: Used in association with embolization coils
                                          • Stent-assisted coil embolization: Noncovered stent placed across wide neck aneurysm
                                            • Coils introduced through stent interstices into aneurysm/pseudoaneurysm using microcatheter

                                    PREPROCEDURE

                                    • Indications

                                      • Contraindications

                                        • Getting Started

                                          PROCEDURE

                                          • Patient Position/Location

                                            • Procedure Steps

                                              • Alternative Procedures/Therapies

                                                POST PROCEDURE

                                                • Things to Do

                                                  • Things to Avoid

                                                    OUTCOMES

                                                    • Problems

                                                      • Complications

                                                        • Expected Outcome

                                                          Selected References

                                                          1. Doucet J et al: The feasibility of degradable glass microspheres as transient embolic medical devices. J Biomater Appl. 35(6):615-32, 2021
                                                          2. Altun I et al: Blood-derived biomaterial for catheter-directed arterial embolization. Adv Mater. 32(52):e2005603, 2020
                                                          3. Hu J et al: Advances in biomaterials and technologies for vascular embolization. Adv Mater. 31(33):e1901071, 2019
                                                          4. Horbach SE et al: Sclerotherapy for low-flow vascular malformations of the head and neck: a systematic review of sclerosing agents. J Plast Reconstr Aesthet Surg. 69(3):295-304, 2016
                                                          5. Spiotta AM et al: Comparison of techniques for stent assisted coil embolization of aneurysms. J Neurointerv Surg. 4(5):339-44, 2012
                                                          6. Etezadi V et al: Endovascular treatment of visceral and renal artery aneurysms. J Vasc Interv Radiol. 22(9):1246-53, 2011
                                                          7. Zhu X et al: Utility of the Amplatzer Vascular Plug in splenic artery embolization: a comparison study with conventional coil technique. Cardiovasc Intervent Radiol. 34(3):522-31, 2011
                                                          8. Duffy DM: Sclerosants: a comparative review. Dermatol Surg. 36 Suppl 2:1010-25, 2010
                                                          9. Lee BB et al: Management of arteriovenous malformations: a multidisciplinary approach. J Vasc Surg. 39(3):590-600, 2004
                                                          10. de Giovanni JV: The use of Amplatzer devices to occlude vascular fistulae. J Interv Cardiol. 14(1):45-8, 2001
                                                          11. Jackson JE et al: Treatment of high-flow vascular malformations by venous embolization aided by flow occlusion techniques. Cardiovasc Intervent Radiol. 19(5):323-8, 1996
                                                          12. Jander HP et al: Transcatheter gelfoam embolization in abdominal, retroperitoneal, and pelvic hemorrhage. Radiology. 136(2):337-44, 1980