Comparative evaluation of tissue damage induced by ultrasound and impact dual-mode endoscopic lithotripsy versus conventional single-mode ultrasound lithotripsy.

OBJECTIVE: The aim of our study was to perform comparative investigation of the tissue safety of three different endoscopic lithotripter devices including a new single-probe/dual-energy lithotripter in an in vivo animal model. The Swiss LithoClast Trilogy was compared to the Storz Calcuson and the Swiss LithoClast Vario. The safety test simulated the accidental direct contact between lithotripter probes and the urothelium, which can occur when sliding off a stone or drilling through a calculus during lithotripsy. The safety test included a smallest (1.5 mm) and largest (3.3/3.4 mm) probe diameter per device. METHODS: Testing was performed in nine pigs (three animals per device). The bladder tissue was exposed to direct lithotripter probe contact at maximum power for 10 s to produce visible tissue lesions. Acute tissue trauma was evaluated using a simplified scoring model describing the expected bladder wall injuries for histological examination. After 7 days, all animals were killed, necropsied and examined post mortem. For between-group comparisons regarding microscopic histopathologic features, a Chi-square test was used. A p value < 0.05 was considered to be statistically significant. RESULTS: Irrespective of the lithotripter used, no systemic signs of toxicity were observed. Histologically, signs of normal ongoing healing were observed on the bladder mucosa. There were no significant differences in histological findings taking changes of the epithelium (p = 0.360), the leucocyte infiltration (p = 0.123), the vascular congestion (p = 0.929) and the edema (p = 1.0) between the groups into account. CONCLUSIONS: The results of this study demonstrated a comparable safety between all lithotripsy devices.

The PolyScope: a modular design, semidisposable flexible ureterorenoscope system.

PURPOSE: To characterize the mechanical and optical properties of the PolyScope endoscope system and to examine the clinical outcome in patients who were undergoing ureteronephroscopy. MATERIALS AND METHODS: Mechanical assessment involved measurement of the deflection angle and irrigation flow rate. Optical resolution and distortion, field and angle of view, and light transmission and output formed the optical assessment. Clinical assessment was made in a series of consecutive ureteronephroscopy procedures. The optical cord was disconnected after each procedure, and the image fiber was assessed for damage. RESULTS: The mean value for the angle of maximum active tip deflection with an empty working channel was 265 degrees (261-275 degrees). Deflection was impaired most with insertion of the 3.0 F basket (10% decrease) and least with an indwelling 220 microm laser fiber (2% decrease). Irrigation flow rate was 57 mL/min with an empty working channel. Flow was reduced by 50% and 68%, with the insertion of a 200 microm or 365 microm laser probe, respectively, and by 92.5% with a 3.2F basket. No damage to the image fiber occurred. The PolyScope optics system could identify a target of about 0.125 mm at a distance of 2 to 4 mm, based on 3 line-pairs/mm needed for clear identification. Lithotripsy of renal calculi was performed for 40 stone burdens in 32 patients; the resulting stone-free rate was 87.5%. CONCLUSION: The novel semidisposable ureteroscope system PolyScope was simple to use, effective, and reliable in this preliminary clinical evaluation. It overcomes the inherent fragility of comparable devices, which renders the need for maintenance unnecessary.