Overview of Embolizing Agents

Dr. Sujeet Agrawal

JR III Radiodiagnosis

Tata Memorial hospital

Introduction:

• Therapeutic embolization is the intentional endovascular occlusion of an artery or vein.

• Historically, the first agent used for embolotherapy was autologousblood clot.

• Modern embolic agents are either temporary or permanent.

Trauma – Temporary.

AVF – Permanent.

TEMPORARY:

A. PARTICULATES:

1.Gelfoam.2. Avitene.3. Autologous blood clot.

PERMANENT:

A. PARTICULATES:

1. PVA.2.Embolic spheres.3.Drug eluting beads.

B. LIQUIDS :

1.Glue.2.Onyx.3. Alcohol.4. Ethonalamine.5. Sclerosants.

C. MECHANICAL :

1 Coils.2. Vascular plugs.3. Drug eluiting particles.

Indication:• Occlusion of vascular abnormalities which have potential

to cause adverse health effects(aneurysm, malformation etc.).

• Acute or chronic hemorrhage.

• Devascularization of benign or malignant tumours.

• Ablation of non-neoplastic tissue causing adverse health effect (hypersplenism, varicocele).

• Flow distribution to protect normal tissue or to facilitate sub-sequent treatment.

• Endoleak management.

• Vehicle for targeted delivery of drugs or other agents.

Gelfoam:• Gelatin foam is a biologic substance made from purified skin

gelatin.

• Temporary – dissolves after few days to weeks.

• First embolic particle used in humans.

• It is mainly used to either stop bleeding or to devascularize a lesion prior to surgical removal.

• Two different forms:- Powder – 40 - 60 µ m - occludes capillaries.- Sheet – 1 - 2 mm, occludes larger vessels.

Gelfoam

TEMPORARY:

A. PARTICULATES:

1.Gelfoam.2. Avitene.3. Autologous blood clot.

PERMANENT:

A. PARTICULATES:

1. PVA.2.Embolic spheres.3.Drug eluting beads.

B. LIQUIDS :

1.Glue.2.Onyx.3. Alcohol.4. Ethonalamine.5. Sclerosants.

C. MECHANICAL :

1 Coils.2. Vascular plugs.3. Drug eluiting particles.

POLYVINYL ALCOHOL PARTICLES:

• The particles are made from a PVA foam sheet.

• Available in sizes ranging from 100 µm to 1100 µ m.

• Polyvinyl alcohol particles are irregular in shape, which promotes aggregation.

• They can be oblong, oval, irregular, sharp and angulated with small fragments after suspension.

• Permanent occlusion by causing thrombosis and fibrosis.

TEMPORARY:

A. PARTICULATES:

1.Gelfoam.2. Avitene.3. Autologous blood clot.

PERMANENT:

A. PARTICULATES:

1. PVA.2.Embolic spheres.3.Drug eluting beads.

B. LIQUIDS :

1.Glue.2.Onyx.3. Alcohol.4. Ethonalamine.5. Sclerosants.

C. MECHANICAL :

1 Coils.2. Vascular plugs.3. Drug eluiting particles.

TRIS-ACRYL GELATIN MICROSPHERES/SPHERICAL EMBOLICSMicrospheres are biocompatible, hydrophilic,

non-resorbable, precisely calibrated acrylic

polymer microspheres.

1. Embosphere Microspheres.

2. Hepasphere Microspheres.

3. Quadrasphere Microspheres.

4. Embozene.

5. Oncozene.

• Ease of injection and less clogging of catheters, resulting in more predictable levels of occlusion.

• More complete occlusion of the vessel.

• Loadable.

• Entire microsphere loads and absorbs drug.

• Sustained drug delivery.

• Homogenous drug dispersion.

1.Embosphere:• Precisely calibrated acrylic polymer microspheres impregnated with

porcine gelatin.

• Embosphere Microspheres are indicated for use in embolization of arteriovenous malformations, hypervascular tumors, and symptomatic uterine fibroids.

• Embospheres are available in six size ranges: 40 to 120 µm,100 to 300 µm, 300 to 500 µm, 500 to 700 µm, 700 to 900 µm, and 900 to 1200 µm.

• 8 ml glass vial closed with screw-top cap.

• Contents: 1 ml or 2 ml of microspheres in pyrogen-free, sterile, NaCl 0.9% saline solution.

• Total volume of saline and microspheres: 5 ml.

2.Hepasphere:• HepaSphere Microspheres are calibrated, spherical, hydrophilic

microspheres made from 2 monomers (vinyl acetate and methyl acrylate) that combine to form a copolymer (sodium acrylatealcohol copolymer).

• This design allows a more complete and targeted occlusion of the blood vessels with or without delivery of doxorubicin HCl for therapeutic or preoperative purposes in the following procedures:

• Embolization of hepatocellular carcinoma.

• Embolization of metastases to the liver.

When in contact with non-ionic contrast media or normal saline (NaCI 0.9%) before delivery, Hepa/QuadraSphereMicrospheres expand to approximately 4x their dry state diameter.

HepaSphere Microsphere’s unique advantages:

• Targeted: Flow directed due to spherical shape.

• Absorbing: Rapidly absorbs aqueous solutions such as contrast media, saline, or reconstituted doxorubicin HCI.

• Expanding: Expands up to four times the stated dry diameter when hydrated.

The doxorubicin is loaded and eluted by a reversible ionic exchange mechanism. The negatively charged acrylate of HepaSpheresMicrospheres interacts with the positively charged doxorubicin hydrochloride.

It enables higher drug concentration that is precisely targeted and delivered directly to the tumor site, resulting in fewer drug-related adverse events. A major advantage of drug-delivery TACE compared to conventional TACE is improved patient safety as a result of lower systemic doxorubicin circulation, resulting in less impact on normal liver function.

3. Quadrasphere Microspheres – same as hapasphere ( US only).

4. Embozene Microspheres.

5. Oncozene Microspheres.Embozene/ Oncozene microspheres are precisely calibrated

microspheres engineered for greater embolization control. Unique colored sizing allows for improved visualization during suspension.

Vascular embolization is a high-risk procedure. Complications may occurat any time during or after the procedure and include:

• Paralysis resulting from untargeted embolization or ischemic injuryfrom adjacent tissue oedema.

• Undesirable reflux into normal arteries adjacent to the targeted lesion such as the internal carotid artery, pulmonary, or coronary circulation or Ischemic stroke.

• Pulmonary embolism due to arteriovenous shunting.

• Vasospasm.

• Blindness, hearing loss, and loss of smell.

• Foreign body reactions, Infection.

• Complications related to catheterization.

• Vessel or lesion rupture and hemorrhage.

• Death.

Complications:

TEMPORARY:

A. PARTICULATES:

1.Gelfoam.2. Avitene.3. Autologous blood clot.

PERMANENT:

A. PARTICULATES:

1. PVA.2.Embolic spheres.3.Drug eluting beads.

B. LIQUIDS :

1.Glue.2.Onyx.3. Alcohol.4. Ethonalamine.5. Sclerosants.

C. MECHANICAL :

1 Coils.2. Vascular plugs.3. Drug eluiting particles.

Drug eluting particles:

• PVA hydrogel polymers.

• Two types:

1. Unloaded.

2. Loaded.DEBDOX,DEBIRI

TEMPORARY:

A. PARTICULATES:

1.Gelfoam.2. Avitene.3. Autologous blood clot.

PERMANENT:

A. PARTICULATES:

1. PVA.2.Embolic spheres.3.Drug eluting beads.

B. LIQUIDS :

1.Glue.2.Onyx.3. Alcohol.4. Ethonalamine.5. Sclerosants.

C. MECHANICAL :

1 Coils.2. Vascular plugs.3. Drug eluiting particles.

Glue:

• Cyanoacrylate.

• Liquid monomeric cyanoacrylte converts to solid immediately on contact with plasma, blood cells, endothelium etc.

Onyx:

• It is etylene vinyl alcohol copolymer dissolved in various concentrations of dimethyl sulfoxide(DMSO).

Sclerosants:

• Sodium tetradecyl sulfate.

• Anionic surfactant.

• Sclerosis of esophageal varices and varicose veins.

• It is a detergent containing 2 % benzyl alcohol.

TEMPORARY:

A. PARTICULATES:

1.Gelfoam.2. Avitene.3. Autologous blood clot.

PERMANENT:

A. PARTICULATES:

1. PVA.2.Embolic spheres.3.Drug eluting beads.

B. LIQUIDS :

1.Glue.2.Onyx.3. Alcohol.4. Ethonalamine.5. Sclerosants.

C. MECHANICAL :

1 Coils.2. Vascular plugs.3. Drug eluiting particles.

Coils:

TEMPORARY:

A. PARTICULATES:

1.Gelfoam.2. Avitene.3. Autologous blood clot.

PERMANENT:

A. PARTICULATES:

1. PVA.2.Embolic spheres.3.Drug eluting beads.

B. LIQUIDS :

1.Glue.2.Onyx.3. Alcohol.4. Ethonalamine.5. Sclerosants.

C. MECHANICAL :

1 Coils.2. Vascular plugs.3. Drug eluiting particles.