New kid on the block “Swiss lithoclast Trilogy™”

Abstract

The quest to discover newer devices for improving stone clearance is ongoing. The variety of devices include Olympus ShockpulseTM and Lithoclast® Select and StoneBreakerTM and electromechanical LithoBreakerTM. The New kid on the block is the “Swiss lithoclast TrilogyTM” [1, 2]. An ideal single probe device should fulfill the following expectation namely, it should minimize the puncture-exit operative time, reduce nephoscopy time and overall operative time with excellent stone clearance [1]. The success in terms of efficacious percutaneous intervention for urolithiasis is dictated by the stone size, stone composition, tract size and the energy device used. The advent of newer technological innovations in this arena has added a new dimension to this aspect, namely the size of the working channel of the nephoscope and the compatibility of the energy probe with the working channel. The authors of this paper need to be applauded for the first multicentre European study trial on the subject [3]. It is noteworthy that the authors found Swiss lithoclast TrilogyTM to be a surgeon friendly device. This finding would open vistas for multicentre studies comparing “Swiss lithoclast Trilogy” with other devices. Although this study reiterates the fact that single probe dual energy device have a number of advantages, a few points merit mention, namely: First, the efficacy of an energy probe depends on size of the probe, meaning, a larger energy probe size will lead to faster clearance of stones while a smaller probe will lead to slower disintegration and clearance of stone. It would be worthwhile to note that Sabnis et al. in the first clinical study on “Swiss lithoclast TrilogyTM” utilized the 1.9 mm and 3.4 mm trilogy probe for the two groups namely standard PNL and Miniperc. They found a significant difference in stone clearance rates in the two groups which can be related to the probe size used [1]. The fragmentation rates were faster, obviously with 3.4 mm probe. Mean stone volume clearance ratios was 370.5 ± 171 versus 590.7 ± 250 in 1.9 mm and 3.4 mm, respectively. In the series by Thakre et al. among the 157 cases, 133 had tract size of more than 22 Fr, while the rest of the stones were treated with a smaller tract size (less than 22 Fr). [3] Thus, it can be assumed that, majority of the stones in this study were cleared using a larger probe (3.4 mm), effectively leading to a faster disintegration of stone. The clearance rates for both the groups (less than and more than 22 Fr) would be different if a headto-head comparison had been done between the two groups in whom two probe sizes were used. Taking this forward, a prospective randomized multicentre study comparing the efficacy of the two size of probes would be of interest. Second, the efficacy of fragmentation of stone is directly proportional to the composition of stone. The Hounsfield unit of the stone is a surrogate marker considered for assessing this density of stones. Lower the Hounsfield unit faster the fragmentation as the stone would be softer. It will be of important to assess the efficacy of “Swiss lithoclast TrilogyTM” in relation to the stone composition. Last but not the least, the majority of the follow-ups in this study have been using a combination of X-ray, ultrasound and CT scan. This follow-up strategy was deployed in 97 patients, while in the remaining follow-up (38% of the study cohort) was not available [3] The lack of followup could skew the results in terms of interpreting stone clearance. Notwithstanding the aforementioned points and critique, the authors of this paper need to be congratulated for this outstanding European multicentre study, it definitely opens new vistas in the understanding of indications and application of newer energy devices used for stone fragmentation.