Experimental and Computational Laser Tissue Welding Using a Protein Patch

Abstract

An in vitro study of laser tissue welding mediated with a dye-enhanced protein patch was conducted. Fresh sections of porcine aorta were used for the experiments. Arteriotomies were treated using an indocyanine green dye-enhanced collagen patch activated by an 805-nm continuous-wave fiber-delivered diode laser. Temperature histories of the surface of the weld site were obtained using a hollow glass optical fiber-based two-color infrared thermometer. The experimental effort was complemented by simulations with the LATIS (LAser-TISsue) computer code, which uses coupled Monte Carlo, thermal transport, and mass transport models. Comparison of simulated and experimental thermal data indicated that evaporative cooling clamped the surface temperature of the weld site below 100 °C. For fluences of approximately 200 J/cm2, peak surface temperatures averaged 74°C and acute burst strengths consistently exceeded 0.14×106 dyn/cm (hoop tension). The combination of experimental and simulation results showed that the inclusion of water transport and evaporative losses in the computer code has a significant impact on the thermal distributions and hydration levels throughout the tissue volume. The solid-matrix protein patch provided a means of controllable energy delivery and yielded consistently strong welds. © 1998 Society of Photo-Optical Instrumentation Engineers.

Experimental and model analysis on the temperature dynamics during diode laser welding of the cornea

“…This dynamics of transient temperature is similar to the one studied in IR-laser irradiated collagen samples. 25,26 This behavior could be exploited in order to further increase the safety of the welding technique, by using even lower laser powers, but at the expense of longer application times. For example, a power density of 12.5 W / cm 2 could ensure that the temperature rise remains below 30°C, but exposure times of 5 to 10 s per spot would be necessary in order to induce an effective corneal welding in each irradiated spot.…”

Kinetics of a Collagen-Like Polypeptide Fragmentation after Mid-IR Free-Electron Laser Ablation

“…These investigations have involved the use of a photosensitizer acting as a cross-linking agent. Incorporation of such laser-absorbing chromophores enables localized surface heating to limit the area of wound repair, which reduces the extent of collateral thermal damage of the underlying tissue (9). In this article, we demonstrate that it becomes possible to take advantage of native chromophores in a tissue to generate the cross-linking intermediates by tuning the FEL radiation to strongly absorbing vibrational frequencies in a collagen-like molecule.…”