Implantação de stent autoexpansível para tratamento de estenose uretral em cão: relato de caso / Implantation of self-expanding stent for treatment of urethral stenosis in dog - case report

O stent endovascular autoexpansível pode ser utilizado como forma de tratamento para estenose uretral em cães. O stent de nitinol é composto por uma liga de níquel e titânio que permite mudanças em suas estruturas sob a influência da temperatura corporal e tem excelente biocompatibilidade na uretra canina. Este estudo relata o caso de um cão, sem raça definida, 14 anos de idade, com histórico de disúria há duas semanas, diagnosticado com grande quantidade de cálculos e microcálculos na bexiga, no colo vesical e na uretra prostática, também cistite e hiperplasia prostática. Depois de tratamento para cistite, orquiectomia e cistotomia para retirada dos cálculos, porém sem melhora clínica após 30 dias de acompanhamento, com o paciente apresentando disúria, foi realizada uretrocistografia retrógrada, que evidenciou estenose da uretra prostática. Esse paciente foi encaminhado para procedimento de implantação de um stent de nitinol na uretra prostática. Imediatamente após o procedimento e até o presente momento, o paciente apresenta micção espontânea, sem qualquer sinal de disúria, sendo este o primeiro relato no Brasil do uso dessa técnica.(AU)

The endovascular stent is used for treatment of urethral stricture in dogs. The nitinol stent is composed by nickel and titanium alloy that allows changes in its structures under the influence of body temperature and has excellent biocompatibility in the canine urethra. This study aims to report a case of a 14 - year - old male dog without defined breed with dysuria for two weeks. Ultrasonographic evaluation revealed microcalculi and calculi in bladder, prostatic urethral obstruction and prostatic hyperplasia. Cystotomy was performed to remove uroliths, but after 30 days of hospitalization there was no clinical improvement. A double-contrast retrograde urethrocystography was performed and showed persistence of prostatic urethral obstruction. The pacient was submitted to a new surgery to place a self-expanding nitinol stent and presented spontaneous urination after the procedure. This is the first report of this technique in Brazil.(AU)

[Effect of self-expanding bare metal stents of different diameters on the trachea of dogs].

Objective: To study the effect of self-expanding bare metal stents on the trachea of dogs, and therefore to provide useful information for choice of airway stents by interventional physicians. Methods: In this experiment, 8 beagles were randomly divided into 4 groups. Four self-expanding metal stents of different diameters (16, 18, 20 and 22 mm, respectively) were placed in the trachea of these beagles for 3 months and their impacts on normal trachea were observed. Results: In the 16 mm stent group (stent-to-airway diameter ratio 103%), good epithelialization was observed and the tracheal structure had no significant damage. In the 18 mm stent group (stent-to-airway diameter ratio 116%), slight granulation tissues were observed, but the cartilage and outer membrane were normal. In the 20 mm stent group (stent-to-airway diameter ratio 129%), severe granulation tissues were observed. Cartilage was damaged but outer membrane was normal. In the 22 mm stent group (stent-to-airway diameter ratio 142%), no obvious granulation tissues were found. Cartilage was normal, but outer membrane was ruptured. Conclusion: In a certain range, tracheal granulation tissues increased as the stent diameter increased. However, if the stent diameter continued to increase, a decreasing trend of tracheal granulation was observed, but severe tracheal injury by stent expansion force would occur.