V6-05: Differences between high-frequency and long-pulse laser lithotripsy – a practical explanation and an objective evaluation
Lithotripters allowing high-frequency and long-pulse lithotripsy are fairly new techniques used in renal stone treatment. They offer several advantages over standard lithotripsy but their ablation efficiencies and relationships are still unclear. The authors decided to explain these lithotripsy modes in a straightforward manner, as well as to objectively evaluate and assess their individual lithotripsy performances.
The authors use a video to illustrate the differences between standard, high-frequency, and long-pulse lithotripsy. They discuss some of their individual features, such as stone fragment size and stone dusting. Afterwards a precise comparison of high-frequency and long-pulse lithotripsy experiments was undertaken using an automated laser fragmentation testing system. Artificial stones made of soft and hard stone material (plaster of Paris and BegoStone®), as well as standard 273-µm core laser fibers (SureFlex from AMS® and MF272STs from Rocamed®) were used in the experiments. Lithotripter settings for high-frequency experiments were set at 40 Hz and at a total power level of 8, 16, 24, and 32W, while long-pulse experiments were done at 15Hz with a total power level of 7.5, 15, and 22.5W. The lithotripters used were the VersaPulse® Powersuite 100W from Lumenis®, and the MH01-ROCA FTS30W from Rocamed®. Additional high-frequency experiments were conducted with a ball-tipped laser fiber, given the increasing trend of using high-frequency with such fibers (AccuTrac from Boston Scientific®). Ablation volumes and laser fiber tip degradation were evaluated.
Long-pulse lithotripsy accomplished higher ablation volumes than high-frequency lithotripsy (p
Long-pulse lithotripsy performed better than high-frequency lithotripsy. Within the range of settings evaluated, long-pulse laser lithotripters, not capable of high-power high-frequency lithotripsy, can still compete with the more heavy-weight lithotripters, capable of very high-frequency lithotripsy. The ball-tipped fiber wasn't more ablative than a standard fiber for high-frequency lithotripsy.