Estudo comparativo da reação inflamatória renal entre álcool de polivinil - flocular e álcool de polivinil + acetato de polivinil - esférico: estudo experimental

Abstract

; Gaudencio Espinosa,TCBC-RJ 5 RESUMO: Objetivo: Avaliar as características e os efeitos de um agente embólico, disponível comercialmente, consistindo de Polivinil Álcool (PVA) de morfologia flocular, e comparar com um agente esférico, de tecnologia nacional, consistindo de Polivinil Álcool e Polivinil Acetato (PVA + PVAc). Método: Foram utilizadas fêmeas de coelho albino "New Zealand", submetidas à embolização arterial renal. PVA-flocular foi usado em 24 animais, assim como PVA+PVAc-esférico. Seis animais foram utilizados como controle. Todos foram mantidos em cativeiro até a morte, por períodos pós-operatórios de 48 horas, cinco dias, 10 dias e 30 dias. Resultados: Ambos os agentes promoveram oclusão do vaso e infarto do órgão. O estudo microscópico inicial das artérias embolizadas com PVA-flocular, mostra oclusão com trombo e PVA. Os vasos embolizados com PVA+PVAc-esférico, mostram os agentes ocupando praticamente todo o lúmen. No estudo de 30 dias, observa-se absorção do trombo e retração dos agentes de PVAflocular, criando espaços. E com PVA+PVAc-esférico, pode-se observar os agentes circundados por intensa fibrose. Conclusões: Ambas as partículas foram efetivas para causar isquemia tecidual. A reação inflamatória foi mais intensa com PVA+PVAc-esférico que também apresentou grau de penetração maior no sistema vascular (Rev. Col. Bras. Cir. 2005; 32(3): 120-126).

An experimental study on the synthesis of poly(vinyl pivalate)-based magnetic nanocomposites through suspension polymerization process

“…For example, when medical applications are considered, uniform morphology is commonly regarded as an essential feature required for polymeric materials successfully used as embolic agent in intravascular embolization procedures (N. B. adopted for the treatment of tumors, aneurysms and arteriovenous malformations). It is expected that spherical polymer particles with a smooth surface presenting a great capacity for mechanical obstruction of the blood vessels, due to the easy accommodation (packing) that promotes interruption of the nutrients supply to the tumor region, which ultimately leads to reduction of tumor size, contribution for faster the tissue recovery [2,45,[70][71][72][73]. Fig.…”

Suspension Copolymerization of Vinyl Acetate and Methyl Methacrylate in the Presence of Amoxicillin

“…The embolization technique is performed by introducing an angiographic catheter into the vascular system and guiding the catheter to the target site, where a fine material is injected as a liquid dispersion, promoting the physical occlusion of the vessel and, consequently, the necrosis of the tissue 20. Apart from its classical applications, the embolization procedure has been used successfully for treatment of other clinical problems, including malignant tumors 21. Particularly, since the original studies presented by Ravina et al,22 uterine artery embolization has been used as alternative treatment in women that would like to preserve the fertility 19…”

Expanded Core/Shell Poly(vinyl acetate)/Poly(vinyl alcohol) Particles for Embolization

“…Nevertheless, typical commercial PVA particles also show some undesirable characteristics, such as the irregular, flock-like morphology and tendency to form particle aggregates (responsible for the difficult flow of the particle suspension through the catheter, which may cause sometimes the catheter occlusion and the interruption of the operation procedures), the fast biodegradability (responsible for the potential recanalization of the treated vascular vessels) and their comparatively high costs. [7] These undesirable characteristics are related primarily to the particles preparation process, which combines the polymerization of vinyl acetate (VAc) in solution, the hydrolysis of the produced poly(vinyl acetate) (PVAc) in solution and the posterior precipitation of the PVA.…”

“…[1,13] Besides, spherical particles are less likely to agglomerate and can penetrate distally on vessels, promoting a permanent and complete occlusion of blood vessels and leading to safer medical interventions. [4,7,14] Many studies compared the performances of spherical and nonspherical particles in embolization procedures, proving the much better efficacy of embolization procedures carried out with spherical particles. [13,15,16] In order to overcome some of the undesirable characteristics of available embolization products, a suspension polymerization process was developed to allow for production of spherical core/shell PVAc/PVA particles for vascular embolization.…”