HISTOPATHOLOGIC APPEARANCE OF ARTERIAL OCCLUSIONS WITH HYDROGEL AND POLYVINYL-ALCOHOL EMBOLIC MATERIAL IN DOMESTIC SWINE

PURPOSE: This study observes the histologic changes resulting from a h ydrogel embolic agent (polyacrylonitrile [PAN]) compared with polyviny l alcohol particles (PVA) of similar size, MATERIALS AND METHODS: Hepa tic and renal embolizations were performed in 13 domestic swine by sel ecting small (l-mm) branches utilizing a coaxial 3-F microcatheter. Th e hydrogel embolic agent (tantalum-loaded and plain) and PVA were deli vered through microcatheters, The longest follow-up period was 8 weeks , Postmortem examination of the embolized tissues included gross exami nation and histologic analysis, RESULTS: Tantalum-loaded PAN particles were radiopaque and seen in groups fluoroscopically and individually with specimen radiography, Histologic studies showed similar luminal a nd cellular response to PVA and the hydrogel embolic agents, The arter ial lesion induced by the hydrogel embolic agents led to an absence of the arterial wall locally in the area of deployment, Hydrogel embolic particles became surrounded in fibrous connective tissue with no arte rial wall, PVA and porous hydrogel capsules produced an inflammatory r esponse, resulting in less wall reorganization, and surrounding fibrou s connective tissue at 8 weeks than the solid PAN particles, CONCLUSIO N: These hydrogel emboli create a permanent arterial occlusion by tran smural arterial damage, Mechanical effects and, to a lesser degree, in flammatory changes are responsible.