Histological studies of myocardium zones irradiated with Nd-YAG laser.

Histological investigation of the dog's myocardium performed 7 and 25 days after irradiation with different doses of Nd-YAG laser show that the damage zone has the shape of a hollow sphere with minor changes in cardiomyocytes in the central part of the sphere. The small blood vessels in the irradiated zone remained undamaged as well. A tentative explanation of the physical process that leads to this type of coagulation zone is given.