The purpose is to present the physics underlying successful laser welding to a clinical audience. Laser welding requires an understanding of the transport of light and heat and the process of denaturation. The methods included both experimental and theoretical studies that illustrate the basics of laser welding. Experiments were performed on the welding of elastin heterographs isolated by alkaline treatment from porcine carotid arteries. The heterographs were stained with indocyanine green (ICG) and both pulsed and CW diode lasers were used for irradiation at 805 nm. Theoretical studies utilized a Monte Carlo model of light propagation coupled to finite-difference model of thermal diffusion and protein denaturation. The experimental results demonstrate the ability to weld ICG-stained elastin heterografts to various substrates, and that there is a temperature dependence to this process. The theoretical results suggest that proteins witha certain range of enthalpic and entropic energies of denaturation are involved in this process. In conclusion, the mysterious technique of laser welding is understandable in in simple physical terms. There are well-defined strategies for laser welding of tissues.
S. L. Jacques, S. A. Prahl, "The physics of laser welding for tissue anatamosis: welding with ICG-stained elastin heterographs," Lasers Surg. Med.,S9, 48 (1997 (abstract)).