Optimal dye concentration and irradiance for laser-assisted vascular anastomosis

Objective: This investigation was done in order to find optimal indocyanine green (ICG) concentration and energy irradiance in laser vascular welding. Background Data: Many studies have shown that laser tissue welding with albumin solder/ICG may be an effective technique in surgical reconstruction. However, there are few reports regarding optimal laser settings and concentrations of ICG within the albumin solder in laser-assisted vascular anastomosis. Materials and Methods: Porcine carotid artery strips (n = 120) were welded in end-to-end by diode laser with 50% albumin solder of 0.01, 0.1, and 1.0 mM ICG at irradiance of 27.7, 56.7, and 76.9 W/cm², respectively. Temperature was measured by inserting thermocouples outside and inside the vessel. Tensile strength and histology were studied. Results: Temperature and strength of the anastomosis significantly decreased (all p < 0.05) with increasing ICG concentration at 56.7 W/cm². Histological study showed minimal thermal injury limited to adventitia and no appreciable difference between all groups. Conclusions: ICG concentration within solder is the most important factor affecting both vascular temperature and tensile strength. The optimal balance between strength and minimal thermal injury may be achieved primarily at 56.7 W/cm² and 0.01 mM ICG.