Effect of laser wavelength and protein solder concentration on acute tissue repair using laser welding: initial results in a canine ureter model.

Successful tissue approximation can be performed using low power laser energy combined with human albumin solder. In vitro studies were undertaken to investigate the acute repair strengths achieved using different laser wavelengths. Furthermore, we evaluated the change in repair strength with that resulted from changes in protein solder concentration. Intraluminal bursting pressure following ureterotomy repair was measured for the following laser wavelengths: 532, 808, 1,320, 2,100, and 10,600 nm. The tissue absorption characteristics of the 808-nm diode and the KTP-532-nm lasers required the addition of the exogenous chromophores indocyanine green and fluorescein, respectively. A 40% human albumin solder was incorporated in the repair of a 1.0-cm longitudinal defect in the canine ureter. Following determination of an optimal welding wavelength, human albumin solder of varying concentrations (25%, 38%, 45%, and 50%) were prepared and tested. The 1,320-nm YAG laser achieved the highest acute bursting pressure and was the most effective in this model. Of the concentrations of albumin tested, 50% human albumin yielded the greatest bursting pressures. We conclude that of the laser wavelengths evaluated, the 1,320-nm YAG achieves the strongest tissue weld in the acute ex vivo dog ureter model. In addition, when this laser system is used, the acute strength of a photothermal weld appears to be directly proportional to the concentration of human albumin solder in the range of 25 to 50%.