[Experimental bladder augmentation with Gore-tex amine: biomechanical, biochemical and biostructural aspects].

We conducted an experimental study on 20 dogs that were subdivided into two groups: the control group comprised 5 dogs that were submitted to resection of 50% of the bladder; the other group comprised 15 dogs submitted to resection of 50% of the bladder and replacement with Gore-tex patch, which was removed 3 months thereafter in 10 dogs. CPK, creatinine, ions, and urinary pH values were determined and urine cultures were performed. The biomechanical parameters of the bladder wall were determined by cystometry. A histological study with hematoxylin-eosin of bladder dome specimens was done. The results showed no increased bladder capacity in the animals that received the Gore-tex implant versus the control animals, chiefly due to the necrosis produced by stiffness of the Gore-tex implant. This necrosis was associated with diminished elasticity (due to collagen) and substitution of the muscle fibers by other viscoelastic fibers with a higher elastic constant. Three months following removal of the Gore-tex implant, we observed fibrotic reaction, secondary calcification of the necrotic bladder wall and inflammatory phenomena that impeded muscle regeneration. The urinary pH increased significantly in the dogs that received the Gore-tex implant. The foregoing results show that although the Gore-tex patch is impermeable and resistant to infection, it does not have the appropriate biomechanical properties.