Histopathological studies of a new liquid embolization method using estrogen-alcohol and polyvinyl acetate. Experimental evaluations with a model of cortical arterial cannulation in the canine brain.

This experimental report evaluates the histopathological effects of a new embolization method using estrogen-alcohol (E-A) and polyvinyl acetate solution (PVac) as tested on 21 mongrel dogs. Three other animals treated with normal saline served as controls. All agents were introduced through an isolated cortical artery. Estrogen-alcohol induced immediate occlusion of small vessels (less than 20 microns), and then progressive obstruction of larger ones (200-300 microns) within several days. Animals treated with PVac showed vascular obliteration (greater than 100 microns) and moderate chronic fibrosis. The effects of embolization using E-A followed by PVac were found to have the combined advantages of both materials, showing diffuse occlusion of the vascular network with less tissue reaction. Hyalinization of embolized vessels with extensive fibrosis occurred afterward. For 6 weeks there was no evidence of recanalization or foreign body giant cell reaction. This study shows that E-A and PVac are capable of producing vascular occlusions with only mild tissue reaction. Because they are easily controllable and have no adverse effects, they may be suitable for intravascular application in the central nervous system.