Laparoscopic renal cryotherapy in swine: comparison of puncture cryotherapy preceded by arterial embolization and contact cryotherapy.
Variable results of open, percutaneous, and laparoscopic cryosurgery of the kidney have been reported. Minimally invasive approaches to lower-pole renal ablation were prospectively compared in swine: laparoscopic puncture cryoablation preceded by arterial embolization, laparoscopic contact cryosurgery, and arterial embolization alone. Eighteen kidneys in nine domestic pigs were randomized to one of three treatment groups of six organs each: (1) puncture cryotherapy preceded by selective lower-pole arterial embolization; (2) contact cryotherapy alone; and (3) arterial embolization alone. Under general anesthesia, appropriate animals underwent selective arterial embolization of the lower pole via femoral cutdown using Gelfoam pledgets. Animals randomized to cryotherapy underwent dissection of the lower pole of the kidney using a single 12-mm umbilical and two midclavicular-line ports in the lateral position. Under external ultrasound guidance, two 3-mm cryoprobes (Cryomedical Sciences, Rockville, MD) were positioned in the lower pole of the kidney, and double-freeze technique to -190 degrees C was performed using puncture or contact application. Ultrasonography was used to guide probe insertion during puncture cryotherapy only. Kidneys were harvested 11 to 14 days after the procedure. Both puncture and contact kidneys demonstrated cell death and subsequent necrosis by light microscopy and electron micrography. On average, puncture lesions were heavier than contact lesions, 19.3 g v 10.1 g (P = 0.02; unpaired t-test), whereas the kidneys were equivalent in weight: 74.1 g v 74.1 g. Puncture lesions represented 26.4% of total kidney weight v 13.5% in the contact group (P = 0.002; unpaired t-test). Only focal infarcts were identified in the embolization group. No evidence of adjacent visceral injury was identified in any of the groups, and no animal required conversion to open laparotomy. One kidney bled after contact cryotherapy, and hemostasis was achieved laparoscopically. Laparoscopic cryotherapy is reproducible and effective using either the puncture technique preceded by arterial embolization or the contact technique, without evidence of damage to adjacent structures. Contact lesions were less voluminous and more peripheral than puncture lesions. Embolization alone produces focal infarcts and focal zones of cell death.