DEVICES, COILS AND EMBOLIC AGENTS IN INTERVENTIONAL

RADIOLOGY

DR. CHIRANJIB MURMURESIDENT, RADIOLOGY

PNCTURE NEEDLE

Simple 18 Guage Angiographic puncture needle - one-piece open needle with a sharp bevelled tip. Guidewire is introduced directly through the needle once the tip is fully within the bleeding vessel lumen. This style of needle can be used for both arterial and venous punctures.

1. PUNCTURE NEEDLE

PUNCTURE NEEDLE

SELDINDER-PROCEDURE

OTHER SITES

• Can also be done in : Brachial/axillary artery• Because: • Absence of femoral pulse• Impossibility of femoral puncture due to prior surgery (femoro-

femoral by-pass)• Leriche syndrome• Better angle in access( celiac artery/SMA/sometimes renal

arteries)

Sheath

Sheath

Balkin’s Cross over sheath Placed on contralateral side after crossing over the aortic bifurcation. Facilitates easy access and treatment to lesions in the Iliac / SFA and high tibial arteries.

Vascular sheath

• Placed over the wire, through the access site. open at one end and capped with a hemostatic valve at the other. Walls are non tapered – bevelled to closely match the dilator size so as to give a smooth transition between sheath and dilator. Available in various lengths and diameters. Diameter of a sheath is measured in “French”. Sheath selection is based on intended purpose • Short 4 / 5 Fr sheaths for diagnostic purposes. Long sheaths with larger diameters for interventions.

Common guidewires

Left to right

Straight 0.038-inch; J-tipped 0.038-inch with introducer device (arrow) to straighten guidewire during insertion into needle hub; angled high-torque 0.035-inch; angled hydrophilic-coated 0.038-inch nitinol wire with pinvise (curved arrow) for fine control; 0.018-inch platinum-tipped micro wire.

Basic construction of common guidewires

1/2 -Curved and straight safety guidewires with outer coiled spring wrap, central stiffening mandril welded at back end only, and small safety wire (arrow) welded on inside at both ends.

3-Movable-core guidewire in which mandril can be slid back and forth and even removed completely to change wire stiffness, using handle incorporated into guidewire (arrow).

4-Mandril guidewire in which soft spring wrap is limited to one end of guidewire (arrow). Remainder of guidewire is a plain mandril.

5-Mandril guidewire coated with hydrophilic substance (arrow).

Guidewires are available in a number of thicknesses, lengths, tip configurations, stiffness and materials of construction.

• Guidewire - the same as or slightly smaller than the diameter of the lumen at the tip of the catheter or device that will slide over it.

• Too big will jam, usually at the tip of the catheter.

• If a guidewire is much smaller than the end hole of the catheter or device, there will be a gap between the guidewire and catheter that can cause vessel injury or prevent smooth movement over the guidewire.

• Thickness measured in one hundrethds of an inch : 0.038 Inches,0.035 inches, 0.014 inches etc.

CATHETERS

• Common catheter shapes.

1 Straight; 2Davis (short angled tip);

3 Multipurpose (“hockey-stick”);

4 Head hunter (H1); 5 Cobra-2 (cobra-1 has tighter curve, cobra-3 has larger and longer curve); 6 Rosch celiac;

7 Visceral (very similar to Simmons 1); 8 Mickelson; 9 Simmons-2; 10 Pigtail; 11 Tennis racket.

Catheters

Flush catheters • Allow high-flow injections into the aorta or inferior vena cava. • Uniform dispersal (with minimal recoil) of contrast media via multiple side holes. • The tip is usually designed to help center the shaft in the vessel and prevent engagement and injection into a branch vessel.

Selective catheters

• Have rotational stiffness to seek a vessel orifice but with enough flexibility to pass the catheter far into the vessel.

• Shaped in a particular way to seek intended vessel ostium.

Catheters

Catheter outer size is described in French gauge (3F = 1 mm). • Diameter of the end hole (and therefore the maximum size of the guidewire the catheter will accommodate) is described in hundredths of an inch. • The length of the catheter is described in centimeters (usually between 65 and 100 cm). • The shape of the tip is named for either something the catheter looks like (“pigtail,” “cobra,” “hockey stick”), the person who designed it (Simmons, Berenstein, Rösch), or the intended use (celiac, left gastric, “head-hunter”)

COMPLEX CATHETERS

• Complex catheter shapes must be re-formed inside the body after insertion over a guidewire. • Any catheter will resume its original shape, provided there is sufficient space within the vessel lumen and memory in the catheter material. • Some catheter shapes cannot re-form spontaneously in a blood vessel, particularly the larger recurved designs like the Simmons.

SELECTIVE CATHETERIZATION

Choosing a selective catheter shape:

A-Angled catheter when angle of axis of branch vessel from aortic axis is low.

B-Curved catheter (e.g., cobra-2, celiac) when angle of axis of branch vessel is between 60 and 120 degrees.

C-Recurved catheter (e.g. Simmons) when angle of axis of branch vessel from aorta is great.

How to use a cobra catheter

1. Catheter advanced to position proximal to branch over guidewire, then pulled down(arrow).

2. Catheter tip engages orifice of branch. Gentle injection of contrast agent to confirmed location.

3. Soft-tipped selective guidewire has been advanced into branch.

4. Guidewire is held firmly, and catheter is advanced.

5. Catheter in selective position.

How to use a Simmons catheter

1. Catheter is positioned above branch vessel with at least 1 cm of floppy straight guidewire beyond catheter tip.

2. Catheter is gently pulled down (arrow)until guidewire and tip engage orifice of branch.

3. Continued gentle traction results in deeper placement of catheter tip.

4. To deselect branch, push catheter back into aorta (reverse steps 1-3).

MICROCATHETERS

• Small catheters (3F or smaller outer diameter) that are specially designed to fit coaxially within the lumen of a standard angiographic catheter are termed microcatheters.

• Typically 2F to 3F in diameter, with 0.010- to 0.027-inch inner lumens.

• Designed to reach far beyond standard catheters in small or tortuous vessels.

• Wide range of characteristics:

1. stiffness,

2. flow rates,

3. hydrophilic coatings.

Progreat Micro catheter

This is a commonly used micro catheter in peripheral vasculature used to facilitate embolization of Bronchial arteries, GI bleeds, Uterine Fibroid embolization etc. This micro catheter allows embolization with micro particles as well as 0.018 coils.

Echelon 90 Exelcior SL 10

These are microcatheters commonly used in embolization of intracranial Aneurysms.

Micro-catheters

When using a micro catheter, a standard angiographic catheter that accepts a 0.038- or 0.035-inch guidewire is first placed securely in a proximal position in the blood vessel.

• The micro catheter is then inserted through the outer catheter and advanced in conjunction with a specially designed 0.010- to 0.025-inch guidewire through the standard catheter lumen.

• Once a super selective position has been attained with the microcatheters, a variety of procedures can be performed, including embolization, sampling, or low-volume angiography.

GUIDING CATHETERS • Designed to make selective catheterization and interventions easier.

• These catheters can be used in some situations to help position and stabilize standard catheters.

• They are used in circumstances in which standard catheters are difficult to position selectively.

GUIDING CATHETERS

These are large lumen catheters that are placed proximal to give stable position for placement of instruments like microcatheters, coils, stents within target lesion.

Y Connector

These are connected on the hub of guiding catheters for haemostasis and for placement Of microcatheters as well as allow a continuous infusion of heparinized saline from the side port.

Angioplasty Balloon

Principle of Angioplasty : Plaque Fracture, Intimal Tearing, Medial Stretching.

Self Expanding Stent

Have radial force that anchors stent to target vessel as it deploys. Can be made of Nitinol that has thermal memory, they reach full expansion at normal body temperature. Nickel titanium alloy.

Balloon Mounted Stent

Mounted over a balloon, expansion of the balloon Causes deployment of this type of stent. Precise positioning is required and is more rigid. These are not placed over joints as can fracture.

Embolic Protection Devices

Atherectomy Device

Chiba Needle /Biliary Internal – External Drain

Used to gain access to biliary ducts. This can be done under Fluoroscopic Or USG guidance.

This has proximal as well as distal drainage holes that allow drainage of bile proximal to lesion externally. If the drain is internalised, that is the lesion is crossed and distal end is placed in the duodenum then bile is drained via the proximal holes into the Duodenum via distal holes.

Filter

Trapease Filter Greenfield filter

Used to prevent pulmonary embolism in patients with DVT in whom long term anticoagulant therapy is contraindicated. Commonly placed in infra-renal IVC . Can be permanent or temporary. Temporary filters have to be removed within 6 weeks to prevent endothelization of the filter.

EMBOLIZATION AGENTS

DELIBERATE OCCLUSION OF A BLOOD VESSEL TO ACHIEVE A THERAPEUTIC RESULT

Technique has evolved to include nearly every vascular territory and has been used in such diverse clinical applications as :

1. Treatment of tumours

2. Vascular malformation

3. Aneurysm and pseudo aneurysm

4. Varicosities

5. Bleeding Fibroids

6. GI Bleed

DEVICE SELECTION

1. Vascular territory to be embolized2. permanence of occlusion3. Degree of occlusion proximal/distal

PERMANENT LARGE-VESSEL OCCLUSIONS

1. Coils2. Balloons3. Amplatz vascular plug (NITINOL Mesh)4. Guide wires5. Silk suture material6. Procine submucosa

PERMANENT SMALL-VESSEL OCCLUSIONS

1. Particles2. Ethiodol 3. Liquid sclerosants (absolute alcohol/STS)4. Liquid adhesive (NBCA)5. Onyx6. Thrombin

TEMPORARY LARGE-VESSEL OCCLUSIONS

1. Gel foam sponge 2. Autologous clot

TEMPORARY SMALL-VESSEL OCCLUSIONS

• Gel foam powder• Fibrillated collagen• Starch microspheres

GENERAL EMBOLIZATION SCHEME AND CLINICAL INDICATIONS

TemporaryPermanent

AUTOLOGUS CLOT

Advantages : immediate availability, absence of cost and lack of adverse reaction.

Method : aspirate roughly 20 mL of the patient's blood and allow it to clot, then discard the supernatant and reintroduce the clot through the catheter. If desired, the clot can be opacified by adding sterile tantalum powder.

Drawback : Rapid lysis time, which can lead to recanalization within 6 to 12 hours. This problem can be partially overcome by modification of the autologous clot.

Gelfoam

Gel foam Pledgets Gel foam Torpedo

If a very proximal occlusion is desired, Gel foam "torpedoes" can be formed by compressing and rolling strips of Gel foam, which are then loaded into the nozzle of a 1- or 3-mL syringe.

Gel foam

For more distal embolization, a slurry of Gel foam can be created by macerating the pledgets with two syringes and a three-way stopcock: the more passes the Gel foam makes through the stopcock, the more it is fragmented and the smaller the pieces become.

Gel foam

• Gel foam embolization provides a temporary occlusion lasting approximately 3 to 6 weeks.

• Used for embolization of pelvic trauma or postpartum haemorrhage, especially when there are multiple punctuate bleeding sites from various branches of the internal iliac artery. In such situations, embolization should be initiated with Gel foam slurry to achieve a relatively distal level of occlusion and then followed by Gel foam pledgets or torpedoes.

PVA Particles

Used in bronchial artery embolization, Uterine fibroid embolization etc.

PVA Particles

• Polyvinyl alcohol (PVA) is essentially a plastic sponge that is fragmented and then filtered to a certain size range.

• PVA is available in sizes between 50 and 2000 μm, the typical size ranges used clinically are 300 to 500 μm or 500 to 700 μm.

• Smaller particles have a significant risk of tissue infarction due to their distal level of occlusion. Larger particles may occlude the delivery catheter

PVA

• USES• Predominantly for tumor embolization, either for preoperative

devascularisation or as definitive treatment, such as in uterine fibroid embolization, JNA embolization.

• PVA can be used when treating haemorrhage of a vascular bed with multiple small branches e.g. haemoptysis in patients with chronic inflammatory lung disease.

• Prior to bronchial embolization, the presence of a spinal artery originating from the treated vessel should be excluded.

OTHER PARTICULATE AGENTS

• Microspheres (Embosphere, Biospheres Medical, Rockland, MA). • Embospheres are precisely calibrated, spherical, hydrophilic,

microporous beads made of an acrylic copolymer, which is then cross-linked with gelatin.

• The hydrophilic surface prevents aggregation, allowing a more predictable, uniform vessel occlusion than PVA, as well as easier delivery through small catheters.

• SIR Spheres : Ceramic microspheres have been embedded with the beta emitter Yttrium-90. Provide internal radiation of hepatic malignancies

COILS

COILS• First embolic coils consisted of pieces of stainless steel guidewires onto which strands of wool had been woven to add a matrix for thrombus formation.

• Stainless-steel coils are best suited for high-flow applications due to their high radial force, which helps prevent dislodging.

• Platinum coils are highly visible under fluoroscopy and are much softer than stainless steel. This facilitates accommodation of the coil to the vessel.

• Appropriate sizing is important to ensure occlusion of the vessel at the intended location.

• Gugliemi detachable coil : Coil is welded to the pusher wire in the desired position, the wire is attached to a battery device that sends a current along the wire. The current melts the welded connection between the coil and the wire and detaches the coil without any force. GDCs are mainly used for treatment of intracranial aneurysms.

USES

• Embolization with coils produces a focal occlusion, leaving the vessel distal to the coil patent, similar to surgical ligature. Therefore, coils are utilized in almost any application in which precise vessel occlusion--but not tissue ablation--is necessary.

• Applications for coil embolization include treatment of haemorrhage, occlusion of arteriovenous fistulas and preoperative or pre-stent graft vessel occlusion.

ENDOVASCULAR COILING OF INTRACRANIAL ANEURYSMS

LIQUID - POLYMERS • ONYX

LIQUID - POLYMERS • ONYX

Liquid embolic agent, consisting of ethylene vinyl alcohol copolymer dissolved in dimethyl sulfoxide (Onyx, Micro Therapeutics Inc., Irvine, CA).

• Onyx contains tantalum powder to render it radiopaque. After Onyx is injected into the target lesion, the dimethyl sulfoxide solvent rapidly diffuses away, causing precipitation of the polymer and formation of a spongy cast.

• The cast solidifies from the outside in. Onyx allows a prolonged, controlled embolization because of its nonadhesive nature.

• Used mainly in Cerebral and Peripheral AVM embolization 1 vial=40,000 rup

GLUE

• n butyl cyanoacrylate-NBCA

• Tissue adhesive• Polymerized when they come in contact with ionic

environment• They are to be injected via catheter which is to be flushed

completely with a non-ionic solution before and after each injection to prevent polymerization of agent within catheters.

• 1 vial=500 rup

GLUE + LIPIDIOL

• n butyl cyanoacrylate. This agent is a permanent rapidly acting liquid, similar to glues sold under trade names such as "SuperGlue," that will polymerize immediately upon contact with ions. It also undergoes an exothermic reaction which destroys the vessel wall. Since the polymerization is so rapid, it requires a skilled surgeon. During the procedure, the surgeon must flush the catheter before and after injecting the NBCA, or the agent will polymerize within the catheter. The catheter must also be withdrawn quickly or it will stick to the vessel. Oil can be mixed with NBCA to slow the rate of polymerization.

• Ethiodol - Made from iodine and poppyseed oil, this is a highly viscous agent. It is usually used for chemoembolizations, especially for hepatomas, since these tumors absorb iodine. The half life is five days, so it only temporarily embolizes vessels.

SCLEROSING AGENTS

• Cause protein denaturation, leading to endothelial destruction and vascular occlusion. Occlusion by sclerosants is usually permanent.

• Sodium tetradecyl sulfate (Setrol) and Polidocanol

• Uses : ablation of tumors, solid organs, veins, or vascular malformations.

Vessels to be embolized

Large Small Permanent temporary Permanent temporary

Coil gel foam Onyx, PVA,NBCA gel foamVascular plug Particles PVANBCA

Take home messages

• Clear vascular anatomy is needed.• Patient selection/indication clarification.• Informed written consent is to be taken.• Must be famillial about the devices and embolic agents.• Proper Device selection.• Follow up scan if needed.

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