Hydroxyapatite ceramics as a particulate embolic material: report of the physical properties of the hydroxyapatite particles and the animal study.

BACKGROUND AND
PURPOSE: Hydroxyapatite ceramic microparticles are newly developed embolic materials. The purpose of this study was to evaluate the characteristics, embolic properties of hydroxyapatite ceramic microparticles, and effects of transcatheter embolization from an angiographic standpoint and to histopathologically evaluate the results of animal experimentation.
METHODS: After physical evaluation of the characteristics and embolic properties of hydroxyapatite microparticles (100-250 micro m in diameter), microcatheter superselective renal artery embolization was performed in rabbits by using this material. Follow-up angiography and histopathologic study of 18 rabbits were performed at different intervals within 24 weeks after embolization.
RESULTS: No microcatheter clogging was observed because of excellent visibility of this material in the suspension and because of its excellent navigability due to its nearly oval shape with no "spines." Angiographic renal arterial devascularization was consistently obtained without unexpected proximal occlusions; follow-up angiography showed persistent occlusion. Histopathologic evaluation confirmed satisfactory embolization of peripheral arteries. Chronic inflammatory cells were observed in several vessels containing hydroxyapatite microparticles. No evidence of angionecrosis, hemorrhage, or extraluminal migration was noted in any sections.
CONCLUSION: Hydroxyapatite microparticles are excellent biocompatible embolic materials with good visibility during injection control, capable of producing effective occlusion of the distal arteriocapillary bed.