Temperature increase during in vitro 308 nm excimer laser ablation of porcine aortic tissue

摘要

Abstract: The temperature increase of porcine aortic tissue irradiated with 220 ns XeCl 308 nm excimer laser pulses above ablation threshold have been measured by means of an IR camera. The decay of the temperature increase after a laser pulse is characterized by a fast decay during the first few milliseconds followed by a slow decay over a prolonged period, suggesting temperature accumulation at repetition rates used in laser angioplasty. The decay is adequately described by the theoretical prediction of the diffusion of heat after adiabatic heating of the tissue by a short laser pulse. From the temporal behavior of the decrease of temperature after a laser pulse, attenuation coefficients at 308 nm could be estimated. Attenuation coefficients after a single pulse are smaller than attenuation coefficient after multiple pulses. The temperature increases found in the experiments might explain thermal damage in myocardial tissue in earlier experiments. In an experimental set up simulating the situation during clinical excimer laser angioplasty, temperature increases of 43$DGR@C average were found.!