Sandwich embolization

Cyanoacrylate (Histoacryl) is a tissue adhesive used in duraplasty. The sites at which it is used should be carefully chosen. Cyanoacrylates are also in use for embolization of arteriovenous malformations in the brain. The risk of this procedure is the creation of pulmonary emboli after acrylate glue injection, particularly when delivery systems without flow arrest are used in high-flow vascular brain lesions. Techniques using acetic acid to delay polymerization time and sandwich techniques, in which glue is pushed with dextrose, appear to be more likely to cause this complication (1). 

If, due to small caliber or tortuosity, the mural artery cannot be catheterized, sandwich technique occlusion of the main artery might be a solution (Fig. 5.11), provided the bleeding point is very near to the branching point and no collaterals are visible. However, even if angiographically not apparent, the distal tract of the ruptured artery will be patent in many cases, allowing collateral retrograde re-perfusion. If embolization has not occluded potential anastomoses, early post-embolization endoscopy to ensure sustained hemostasis is mandatory (Fig. 5.11). 

Coil embolization is technically easy and successful. Coils should be sized slightly larger than the vessel lumen. Smaller coils or Gelfoam can be used to sandwich or nest between the flanking coils. This will ensure a compact and occlusive embolus. Patients should be observed for splenic infarction, although short gastric or other small collateral vessels can perfuse portions of the spleen distal to the occluded main renal artery. 

More peripheral aneurysms can be selectively coil embolized using microcatheter techniques. Both distal and proximal control is not always possible, and may not be necessary due to the vascular anatomy. In the presence of multiple aneurysms from a lesion such as an angiomyolipoma, a combination of particle and coil embolization can be performed. If actively bleeding, the aneurysms are coiled first, followed by occlusion of the feeding vessels to the tumor with PVA or embospheres. Gelfoam can be sandwiched between coil nests to assist thrombosis. 

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