Nd‐YAG laser energy distribution in an artificial obstruction: Influence of lasing parameters in a model of laser angioplasty

A Nd‐YAG laser (1064 nm) coupled to a silica fiber (0.6 mm core diameter) was used to create defects in a model of arterial vascular obstruction. We employed transparent agar doped with black ink as atheromatous material and studied the size and shape of defects created by various lasing parameter settings. By adding calcium sulphate to the agar its scattering properties were enhanced. The created defects correspond to a temperature boundary. The optical properties of the agar greatly influenced the size and shape of the created defects. In the agar with enhanced scattering properties, the created defects showed an infavourable penetration width‐depth ratio. Maximum width of penetration always exceeded the fiber diameter. This may contribute to an increased risk of vessel wall perforation in small vessels and, if the fiber is positioned close to the vessel wall, even when a coaxial position is maintained. With increasing cumulative energy, both maximum depth and width of penetration leveled off in both agars. The results suggest that agar can be used to obtain empirically the lasing parameters that will minimize the risk of vessel wall perforation by an axially positioned fiber. The agar model needs further study to determine its limitations, but agar seems to be a useful substitute for atheroma in the study of laser catheter angioplasty.