Lyophilized allografts without pre-treatment with glutaraldehyde are more suitable than cryopreserved allografts for pulmonary artery reconstruction

Various methods are available for preservation of vascular grafts for pulmonary artery (PA) replacement. Lyophilization and cryopreservation reduce antigenicity and prevent thrombosis and calcification in vascular grafts, so both methods can be used to obtain vascular bioprostheses. We evaluated the hemodynamic, gasometric, imaging, and macroscopic and microscopic findings produced by PA reconstruction with lyophilized (LyoPA) grafts and cryopreserved (CryoPA) grafts in dogs. Eighteen healthy crossbred adult dogs of both sexes weighing between 18 and 20 kg were used and divided into three groups of six: group I, PA section and reanastomosis; group II, PA resection and reconstruction with LyoPA allograft; group III, PA resection and reconstruction with CryoPA allograft. Dogs were evaluated 4 weeks after surgery, and the status of the graft and vascular anastomosis were examined macroscopically and microscopically. No clinical, radiologic, or blood-gas abnormalities were observed during the study. The mean pulmonary artery pressure (MPAP) in group III increased significantly at the end of the study compared with baseline (P=0.02) and final [P=0.007, two-way repeat-measures analysis of variance (RM ANOVA)] values. Pulmonary vascular resistance of groups II and III increased immediately after reperfusion and also at the end of the study compared to baseline. The increase shown by group III vs group I was significant only if compared with after surgery and study end (P=0.016 and P=0.005, respectively, two-way RM ANOVA). Microscopically, permeability was reduced by ≤75% in group III. In conclusion, substitution of PAs with LyoPA grafts is technically feasible and clinically promising.

Efecto del ácido hialurónico sobre la cicatrización traqueal en un modelo experimental canino / Effect of the hyaluronic acid on tracheal healing. A canine experimental mode

Se han utilizado varios fármacos para modular el proceso de cicatrización de la tráquea y evitar la formación de una estenosis traqueal. El ácido hialurónico (AH) es un modulador de la fibrogénesis y en este trabajo evaluamos el efecto de la aplicación de éste sobre la cicatrización traqueal, después de realizar anastomosis traqueal término-terminal cervical en perros.En 12 perros mestizos se realizó resección traqueal y sutura cervical y postcirugía se trataron de la siguiente forma: Grupo I (n=6): Se aplicó tópicamente solución salina normal (0,9 por ciento) sobre la anastomosis traqueal y en el grupo II (n=6) se aplicó 15 µg de AH en la anastomosis traqueal. Los animales fueron evaluados clínica, radiológica y mediante endoscopia traqueal durante 4 semanas y fueron sometidos a eutanasia. Se examinó macroscópica y microscópicamente la cicatrización de la anastomosis traqueal y se cuantificó mediante estudio bioquímico utilizando el método de Woessner la cantidad de colágeno formado en ésta. Todos los animales sobrevivieron al procedimiento quirúrgico y al tiempo de estudio establecido. Ningún animal presentó diferencias en la evolución clínica importantes. Los hallazgos radiológicos, endoscópicos y macroscópicos mostraron mayor desarrollo de estenosis traqueal en los animales del grupo I que en los del grupo II. Los estudios endoscópicos y macroscópicos mostraron mayor inflamación y desarrollo de tejido fibroso de consistencia firme en las cicatrices del grupo I que en las del grupo II. Microscópicamente en el grupo I se observó fibrosis y reacción inflamatoria severa. En el grupo II se presentaron depósitos de fibras de colágeno delgadas y bien organizadas con reacción inflamatoria mínima. En las determinaciones bioquímicas se demostró que la concentración de colágeno fue mayor en el grupo I a las del resto, sin que estadísticamente las diferencias resultasen significativas. Nosotros concluimos que el AH aplicado después de la realización de una anastomosis traqueal término-terminal en perros disminuye la formación de estenosis e inflamación traqueal postcirugía y mejora la calidad de la cicatrización traqueal (AU)

Several drugs have been used to modulate of the tracheal healing process in order to prevent tracheal stenosis. Hyaluronic acid (HA) is a modulator of the fibrogenesis. In this work we evaluate the effect in order the application of hyaluronic acid has on tracheal healing, after cervical tracheoplasty in dogs. A cervical tracheal resection and tracheoplasty was performed in 12 dogs and they were treated following surgery as follows: Group I (n = 6) Topical application of normal saline solution (0.9%) on the anastomosis site. Group II Topical application of hyaluronic acid on the trachea anastomosed. The animals were evaluated clinical, radiological and tracheoscopically during 4 weeks and were submitted to euthanasia. Macroscopic and microscopic examinations of the tracheal anastomotic healing were evaluated. Biochemical collagen quantification by the Woessner method was performed to evaluate the collagen development at the anastomotic site. All the animals survived the surgical procedure and the study time. No animal presented differences in clinical evaluation. Radiological and endoscopical findings both two showed more development of the tracheal stenosis in-group than in group II. The tracheoscopy and macroscopic studies showed major inflammation and development of fibrotic tissue with a firm consistency in the healing of the group I than in group II. Microscopic examination in group I showed severe fibrosis and inflammatory reaction. The group II presented deposits of a thin and organized collagen fibers and minimal inflammatory reaction. Biochemical collagen concentration was larger in-group I, however significantly. We conclude that the hyaluronic acid applied after cervical tracheoplasty in dogs reduces postsurgical tracheal stenosis and inflammation, as well as improve the quality of the tracheal healing (AU)