Ultrashort intracorporeally maneuverable cryoprobes for laparoscopic renal cryoablation in the porcine model

Aim: To determine the feasibility and efficacy of laparoscopic renal cryosurgery using a novel ultrathin ultrashort intracorporeal cryoprobe in a porcine model. Material and methods: Novel cryoprobes 4 cm in length and 1.5 mm in diameter were manipulated intracorporeally after insertion via a designated 15 mm laparoscopic port. Renal cryoablative lesions were induced laparoscopically in four 40 kg female piglets. We correlated between intraoperative temperature, ice ball geometry, intraoperative ultrasonographic properties, and histology. Results: Laparoscopic manipulation of the cryoprobes was straightforward. No port site bleeding occurred during insertion, freezing, thawing or upon removal of the probes. The 0°C, -20°C, and -40°C isotherms were measured at 6, 8, and 12 mm from the probe circumferentially. Ice-ball volume stabilization as determined by ultrasound occurred after 10 min of activation. Lower temperatures were reached after 10 min of probe activation as compared with 5 min (ice ball diameter 30 mm, ΔT = 13-21°C). Using a second 10-min-long freeze cycle resulted in a 14-22°C lower temperature within the ice ball compared to a single cycle. Full coagulative necrosis was noted in the areas between the inserted probes with an additional 1-2 mm circumferential rim of severe tubular damage and apoptosis. Conclusions: Our novel cryoprobe can be used effectively and conveniently in laparoscopic renal cryosurgery. Considering the size of the cryogenic lesion, using a cluster of probes may be advisable.