Purpose: To evaluate the feasibility and efficacy of antegrade renal cooling during radiofrequency (RF) ablation to protect the renal collecting system in pigs.
Materials and methods: With the approval of the institutional animal care and use committee, RF ablation was planned bilaterally after nephrostomy in 20 kidneys from 10 domestic pigs. A coaxial assembly consisting of a 7-F pigtail catheter and a 12-F arterial sheath was placed at the renal pelvis. Cooled 5% dextrose in water solution was perfused in only one of the kidneys in each pig. A 17-gauge internally cooled tip RF electrode with a 3-cm tip was placed near the renal pelvis with ultrasonographic guidance. On postprocedural days 1 and 7, computed tomography (CT) was performed to evaluate the RF ablation effect, the presence of a fluid collection, and the leakage of contrast material. Ex vivo retrograde pyelography was performed to assess the integrity of the urinary tract after kidney harvest. Histologic findings related to the urothelial damage were scored semiquantitatively.
Results: The mean maximal diameter of the RF ablation area measured at CT and in specimens was not significantly different between cooled and noncooled kidneys. A fluid collection around the RF ablation area was seen in eight of the 10 noncooled kidneys on day 7 CT scans compared with two of the 10 cooled kidneys; the difference was statistically significant (P = .035). Ex vivo retrograde pyelography depicted leakage of contrast material in only the noncooled group. The mean histologic damage score was lower in the cooled group than in the noncooled group.
Conclusion: RF ablation after placement of an antegrade cooling system in pig kidneys was feasible. Antegrade cold dextrose infusion of the urinary tract during RF ablation is effective in protecting the renal collecting system without compromising the RF ablation effect.
(c) RSNA, 2010.