Retrograde renal cooling during radio frequency ablation to protect from renal collecting system injury

Purpose: We evaluated the protective effect of continuous retrograde irrigation of ice-cold saline on the renal collecting system during central parenchymal temperature based radio frequency ablation (RFA). Materials and Methods: In 10 domestic pigs bilateral, centrally located renal parenchymal RFA lesions (intended 2 cm in diameter) were created that intentionally involved the collecting system. RFA probe placement was guided by fluoroscopy with retrograde collecting system opacification and simultaneous direct laparoscopic visualization. In 1 renal unit RFA was performed while infusing ice-cold saline through a previously placed ureteral access sheath and pigtail stent. RFA without renal cooling was performed in the contralateral renal unit. Kidneys were harvested at 7 days. The renal collecting system was inspected for injury by performing retrograde pyelograms and by histological examination of the collecting system adjacent to the ablation zone. The size of RFA lesions was measured. Results: In retrograde cooling procedures the temperature of saline irrigant was -1.0C and the mean temperature of the effluent was 13C. One of 10 cooled renal units demonstrated contrast material extravasation from the collecting system involved by the ablation zone compared with 7 of 10 noncooled renal units (p = 0.025). Lesion size was comparable between cooled kidneys and controls (2.67 and 2.72 cm, respectively, p = 0.629). Conclusions: Retrograde renal cooling helps protect the renal collecting system from injury during RFA without a decrease in expected lesion size. Clinically retrograde renal cooling may decrease the risk of collecting system injury and subsequent complications during RFA.