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A lesao da parede arterial provocada por balao de angioplastia ou implante de proteses endovasculares em modelos experimentais e humanos pode provocar a reestenose do vaso, principalmente por migracao e proliferacao de celulas musculares lisas e sintese de matriz extracelular. Varios estudos demonstraram que a braquiterapia intra-arterial atua nestes fatores e, consequentemente, no tratamento da reestenose coronariana. Este estudo tem por objetivo avaliar as alteracoes vasculares morfologicas e morfometricas induzidas pela braquiterapia com samario-153 (153Sm), utilizando uma dose considerada ideal e outra elevada em coelhos hipercolesterolemicos. Foram analisados 43 coelhos hipercolesterolemicos e um total de 86 arterias iliacas submetidas a lesao por balao de angioplastia, divididos em tres grupos, sendo irradiados com as doses de 15Gy (n = 14) e 60Gy (n = 36) e controle (n = 36). Foram realizadas analise morfometrica (area neo-intimal, area da camada media, area do vaso) e analise histologica qualitativa para avaliacao tecidual. O colesterol medio foi de 1.362 ± 497mg/dl nos tres grupos. O achado mais relevante foi uma significativa inibicao da hiperplasia neo-intimal no grupo irradiado com a dose de 15Gy, maior do que o controle e com a dose de 60Gy. Na dose de 60 Gy, alem de ineficaz para inibir a proliferacao neo-intimal, teve caracteristicas tissulares e estruturais sugestivas de radiolesao, como presenca de celulas xantomatosas, tecidos hialino e amorfo, proliferacao vascular. Estas celulas, bem como o aumento das dimensoes morfometricas do vaso, foram proporcionais aos graus de lesao nas lâminas elasticas interna e externa, sendo observados principalmente com a dose de 60Gy. Os segmentos medios das arterias iliacas, representando o local de maior contato com o balao, tiveram maiores alteracoes morfometricas e celulares em relacao aos segmentos referenciais (proximal e distal) nos tres grupos. Em conclusao, o grupo de arterias submetidas a irradiacao de 15Gy foi eficaz para a inibicao da proliferacao neo-intimal. O grupo irradiado com a maior dose de 60Gy foi ineficaz para inibir a hiperplasia neo-intimal e apresentou caracteristicas morfometricas e teciduais compativeis com a radiolesao vascular.

Background: It has been shown that irradiation with either beta and gamma sources inhibit neointimal formation. Samarium-153 (153Sm) is an isotope with 0.8 MeV, subdivided in three different beta energies and 103 keV of gamma energy. This compound has been tested and used in humans for palliation of pain from bone metastases. The aim of the present study was to evaluate the feasibility and efficacy of brachytherapy with 153Sm-filled balloon to inhibit neointimal formation in rabbits after balloon overstretch injury. Methods: Nineteen rabbits underwent balloon injury in their iliac arteries. In 12 animals (control), oversized balloons filled with saline solution were inflated up to 5 atm for a period of 5 min. In 7 rabbits, the same procedure was performed but using balloons filled with 153Sm. In all cases, both iliac arteries were treated. The prescribed radiation dose was 15 Gy at 1 mm depth. After 30 days, the animals were sacrificed and their arterial segments were analyzed. Radiation exposure at the animal chest to the table and at a distance of 1 m from the table was measured. Results: Histopathologic analysis showed a striking reduction in the amount of neointima in the irradiated arteries compared with control vessels (0.36±0.21 vs. 1.07±0.56 mm2, P

OBJETIVO: Este estudo tem por objetivo avaliar as alterações vasculares morfológicas e morfométricas induzidas pela braquiterapia com Samário-153 (153 Sm) em coelhos hipercolesterolêmicos, com doses elevadas. MÉTODOS: Foram analisados 43 coelhos hipercolesterolêmicos, brancos, da raça New Zealand, e o total de 86 artérias ilíacas submetidas a lesão por balão de angioplastia. Divididos em três grupos: dois (GI) irradiados com as doses de 15Gy (n=14) e 60Gy (n=36) e um grupo controle (n=36). Foram realizadas avaliação histológica morfométrica e análise histológica qualitativa para análise tecidual. RESULTADOS: Foram observadas uma redução significativa da neoproliferação intimal (NPI) no GI 15 Gy (p

This study was designed to evaluate vascular morphological and morphometric changes induced by brachytherapy with samarium-153 (Sm-153) at high doses in hypercholesterolemic rabbits.Forty-three New Zealand White hypercholesterolemic rabbits were analyzed, and the total of 86 iliac arteries underwent balloon angioplasty injury. The rabbits were divided into three different groups: two irradiation groups (IG) assigned to 15 Gy (n=14) and 60 Gy (n=36) irradiation doses, respectively, and a control group (n = 36). Histomorphometric and qualitative histological analyses were performed for tissue evaluation.Significant reductions were found in neointimal proliferation (NIP) (p0.0001), media area (MA) (p0.0001) and percent stenosis (p0.0001) in the 15-Gy IG, compared to the other groups. The 60-Gy IG had the higher rate of NIP, increase in media and vessel areas (VA) and percent stenosis. The 60-Gy IG also showed the greatest number of xanthomatous cells (60-Gy IG: 86.11% and 15-Gy IG: 14.29%, p0.0001) and the highest amount of hyaline amorphous tissue (60-Gy IG:58.33% and 15-Gy IG:0%, p=0.0001) and vascular proliferation (60-Gy IG:30.56% and 15-Gy IG:0%, p=0.0221). No statistically significant differences were found among groups concerning other tissue analyses.The high-dose irradiation of 60 Gy resulted in intense cell proliferation considered vascular radiolesion, unlike the 15-Gy dose, which was associated with an excellent inhibition of neointimal proliferation.