Preclinical assessment of the multi-YAG laser for intracorporeal lithotripsy of human urinary calculi

The dual wavelength Nd:YAG (multi-YAG) laser is a multi-purpose surgical laser designed to emit 1440 nm light in the pulsed mode for ablation of tissue. A three-part experimental study was undertaken to define the optimal parameters for laser lithotripsy and also to investigate the safety of this laser for fragmenting ureteral calculi.; Urinary calculi were first ablated in an in vitro study (n = 120). Lithotripsy was then performed in an ex vivo pig model (n = 45) and in nine female swine in order to study the acute and chronic tissue effects of treatment.; Fragmentation efficacy was significantly affected by the pulse energy (p {dollar}<{dollar} 0.001). The most efficacious and rapid fragmentation occurred at energies between 0.6 J and 0.9 J/pulse. Ex vivo lithotripsy caused low grade acute tissue effects in 37/42 cases and moderate to high grade injury in five ureters. There were no chronic high grade injuries in the in vivo model. These results suggest that the multi-YAG laser can efficiently ablate urinary stones with acceptable levels of acute and chronic tissue injury.