Thermal damage processes follow kinetic governing relations and resultant damage depends on both temperature and time of exposure. Application to models of cardiac ablation depends on identification of a quantitative measure of thermal damage. Loss of the native state birefringence of myocardium is one such measure. Damage data derived from short term argon laser exposure and long term heated block experiments were adapted to model middle term heating as in cardiac ablation. Model predictions from the estimated coefficients compare favorably to the experimental observations; however, much remains to be learned about the true kinetic nature of the damage processes in this tissue.