Determination of the most efficient temperature for radiofrequency ablation of renal cells: a prospective study in dogs.
OBJECTIVE
Radiofrequency (RF) ablation of renal tumors is a major technique for tumor cell destruction while preserving healthy renal parenchyma. There is no consensus in the literature regarding the optimal temperature, impedance, and time for RF application for effective cell destruction. This study investigated two variables while keeping time unchanged: Temperature for RF cell destruction and tissue impedance in dog kidneys.


METHODS
Sixteen dogs had renal punctures through videolaparoscopy for RF interstitial tissue ablation. A RF generator was applied for 10 minutes to the dog's kidney at different target temperatures: 80 degrees C, 90 degrees C, and 100 degrees C. On postoperative day 14, the animals were sacrificed and nephrectomized. All lesions were macroscopically and microscopically examined. The bioelectrical impedance was evaluated at three different temperatures.


RESULTS
Renal injuries were wider and deeper at 90 degrees C (P < 0.001), and they were similar at 80 degrees C and 100 degrees C. The bioelectrical impedance was lower at 90 degrees C than at the temperatures of 80 degrees C and 100 degrees C (P < 0.001). Viable cells in the RF ablation tissue area were not found in the microscopic examination.


CONCLUSIONS
The most effective cell destruction in terms of width and depth was achieved at 90 degrees C, which was also the optimal temperature for tissue impedance. RF ablation of renal cells eliminated all viable cells.
Queiroz
Marcus
M
Learning and Research Surgery Center (CEPEC) Vicky Safra, and Urology Department, Universidade de São Paulo Medical School (FMUSP), São Paulo, Brazil. mvbqueiroz@globo.com
Duarte
Ricardo
R
Chan
Chen
C
Saldanha
Luiz
L
Mitre
Anuar
A
Srougi
Miguel
M
D000818:Animals; D017115:Catheter Ablation / Q000379:methods*; D004285:Dogs; D017097:Electric Impedance; D007668:Kidney / Q000473:pathology* / Q000601:surgery*; D009336:Necrosis; D011446:Prospective Studies; D011677:Punctures; D013696:Temperature