Tissue perforation of vessel substitutes using a femtosecond Ti:Sapphire laser system

摘要

Preveious investigations of transmural capillary ingrwoth into the inner surface of biosynthetic vascular prostheses through performations created by an excimer laser have shown that spontaneous endothelialization of the protheses can be achieved. Disadvantages of the excimer laser are a large and non-circular beam prifile and an inconventient handling of the UV-radiation for medical applications. Therefore, a new commercial laser system, consisting of a mirror-dispersion-controlled TiS oscillator (FemtoSource Pro HP, peak wavelenth direct a 800nm) and a femtosecond multipass amplifier (FemtopOwer 100), which avoids these disadvantages was used to perforate grafts made of a new biomaterial (carbomedics). The laser-tissue interaction is based on a different mechanism dur to the short pulsewidth (approx. 20-30 fs), high peak intensity and near IR wavelength. The very short pulsewidth reduces thermal damage of the tissue. The basic mechamism of the laser tissue interaction is not yet fully understood and still subject of investigations. Several biografts with 1 mm wall thickness have been used. The hole diameter could be varied between 50 and 200 mu m and the distance between the holes eas 4 mm. At laser intensities of approx. 20-30 TW/cm~2 and a repetition rate of 1 kHz it took less than a second to drill a signle hole Subsequently to the perforation procedure, one perforted and one untreated biograft were implanted into the carotid arteries of several test sheep. It can be concluded that very intense neear IR laser radiation is an ideal means for structuring biological tissue.