Soldagem térmica de tecido biológico rico em colágeno (aorta porcina)

Abstract

Cardiac valve bioprosthesis are manufactured by means of sutures, which brings some disadvantages, as the difficulty of creating an automated process and the stress concentration in the tissue suturing region. Tissue welding is a technique that can replace the suture.Studies were carried out with the purpose to assess the feasibility of applying the thermal welding in the biological tissue used in the bioprosthesis, evaluating its mechanical strength and understanding the mechanisms involved in the process. The experiments involved the direct application of heat in the tissue to be welded. In order to pursue the best results, the following parameters were assessed: temperature,humidity, exposure time, heat application method and chemical fixation. The best method consisted of making an incision in the tissue sample and exposing it to the controlled temperature and humidity in an incubator. The mechanical strength of the weld was evaluated in a tensile test machine. The highest average mechanical strength was obtained from the weld made within the incubator at 40 °C, with a controlled humidity between 30% and 40%. The heat exposure time also increased the mechanical strength, but this difference disappeared after the chemical fixation. The chemical fixation in turn was demonstrated to beessential for the stability of the weld, which disappears after re-hydration in saline solution, if it was not fixed. The best results were obtained with 2.50% glutaraldehyde for 15 days. The results correspond to about half of the average mechanical strength obtained with sutures, but some isolated values showed that the potential to obtain welds with the strength as the suture. Raman spectroscopy and analysis at the SEMshowed that the weld is more associated with chemical bonds between collagen fibers than material fusion