|
| Embolic material | Advantages | Limitations |
|
| N-butyl cyanoacrylate (n-BCA) | (i) Great penetration potential into bAVMs nidus.
(ii) Permanent embolization with durable occlusion of the embolized vessel or pedicle.
(iii) Deliverable through small, flexible, and flow-directed catheters causing minimal trauma even in distal vessels of the cerebrovascular system.
(iv) Easy and quick delivery, infusion generally takes less than 1 minute.
(v) Radiolucent, must be mixed with a radiopaque agent (i.e. ethiodized oil: lipiodol, ethiodol). Usual ratios for the mixture are 1.5 : 1 to 3 : 1 (oil-to-NBCA) with nonnegligible margin of error.
(vi) Radiolucent. Follow-up angiograms and eventual indications for further endovascular surgery are not hampered by radiological artifacts from the first intervention. | (i) Experience is required to judge the best fitted ratio for NBCA/Ethiodol for each different scenario.
(ii) Adhesive-tendency to adhere to the catheter, making withdrawal traumatic or impossible.
(iii) High level of expertise is required to control the injection to achieve adequate nidal obliteration preventing venous dissemination.
(iv) Far higher consistency than ONYX. In case of packed AVM it cannot be removed piecemeal with scissors. |
|
Onyx
| (i) Nonadhesive,
(ii) Great radiopacity—enhanced angiographic control during injection.
(iii) Lesser consistency than NBCA. In a packed AVM can be removed piecemeal with scissors. | (i) DMSO component of the mixture may induce vasospasm and angionecrosis.
(ii) Tantalum powder must be mixed with the agent to provide radiopacity.
(iii) Great radiopacity—follow-up angiograms and eventual subsequent endovascular procedures are hampered by radiological artifacts. |
|
| Ethanol (ETOH) | (i) Sclerosant-dehydration and disruption of endothelium surface with fractures of the vessel walls to the level of the internal elastic lamina resulting in acute thrombosis.
(ii) Great penetration potential. | (i) Risk of significant brain edema.
(ii) It may induce pulmonary precapillary vasospasm possibly leading to cardiopulmonary collapse.
(iii) Great penetration potential-high level of experience is required to perform ETOH embolization safely. |
|
| Polyvinyl alcohol (PVA)/Embospheres | (i) Penetration potential depends on particle size allowing the adoption of different strategies in function of case specific angiographical features.
(ii) Once injected particles expand obstructing vessels with higher diameters than the catheters.
(iii) Particles are far more controllable than embolic liquid agents during injection. | (i) Particulate embolization requires a microcatheter with an internal diameter larger than the particle itself.
(ii) During mixing process, PVA particles may fragment contaminating the mixture with smaller “dangerous” emboli.
(iii) Risk of particles to clump up and/or catheters to be clogged due to particles high friction coefficient. Potential risk of vascular perforation.
(iv) The choice of the particles’ size depends on operator’s interpretation of the superselective angiogram.
(v) Nonpermanent embolization effects—particles may be absorbed or degraded by endogenous lytic agents. Risk of recanalization. Best fitted for presurgical embolization purposes rather than stand-alone endovascular curative procedures. |
|
| Coils | (i) Detachable coils are most useful for the initial embolization of large fistulae.
(ii) Poor penetration potential if compared to particulates or liquid embolic agents-risk of distal dissemination is relatively contained. | (i) Potential for vascular perforation.
(ii) Poor penetration potential. |
|
