In vitro
evaluation of the new holmium:yttrium‐aluminium‐garnet laser with Magneto technology on behalf of the Progress and Collaboration in Endourology (
PACE)
group
Adèle Martin‐Illac, Marie Chicaud, Marie‐Lou Letouche, Stefano Moretto, Federico Zorzi, Alejandra Bravo‐Balado, Carlos Altez Fernandes, Alberto Quarà, Aideen Madden, Letizia Maria Ippolita Jannello, Jorge Peña Lueza, Razvan Ionut Popescu, Luigi Candela, Frederic Panthier, Olivier Traxer, Steeve Doizi, Stessy Kutchukian Objectives
To evaluate the following characteristics of the holmium:yttrium‐aluminium‐garnet (Ho:YAG) laser with Magneto technology: pulse shape, shape and duration of the laser‐induced vapour bubble (VB), power loss over time, and the risk of fibre fracture (RFF).
Methods
A 150 W Ho:YAG generator was characterised in vitro with Magneto technology. The pulse shape was measured using an oscilloscope. The pulse duration was measured to calculate the peak power (PP) using both a 200‐ and 550‐μm laser fibre (LF). VB were evaluated with a 200‐μm fibre using a high‐speed camera (8000 frames/s). Power loss over time was obtained at the fibre tip before and after 30 s, then 1 min of continuous laser activation in saline solution and in contact with BegoStone® (BEGO GmbH & Co., Bremen, Germany). Power loss was evaluated using LFs with core diameters of 200, 365, and 550 μm. RFF was tested after 5 min of continuous laser activation or until LF fracture with different laser settings and LF bending radii (0.45, 0.6, 0.9 cm) using a 200‐μm LF.
Results
The Ho:YAG laser with the Magneto technology possesses a quasi‐rectangular waveform with extended pulse durations ranging between 0.7 and 1.7 ms and limited PPs between a mean (standard deviation) of 513.4 (23.3) to 1149.7 (6.9) W that increase proportionally with power. However, multiple spikes were observed within each pulse, precluding a perfectly linear plateau. Regarding VB, it was significantly wider with the 550‐μm LF compared to the 200‐μm LF. Conversely, the VB duration was significantly longer with the 200‐μm LF. A consistent initial power loss was observed in normal saline of 13–28.0% across all LF diameters, which progressed during continuous activation of up to 1 min. This power degradation was more pronounced on synthetic BegoStone. No LF fractures were observed under the tested experimental conditions.
Conclusion
The new Ho:YAG laser with Magneto technology appears to be a promising compromise between conventional Ho:YAG and thulium fibre laser, owing to its pulse profile with a limited PP.