Transurethral needle ablation (TUNA) of the prostate using low-level radiofrequency energy: An animal experimental study

Transurethral needle ablation of the canine prostate using low level radiofrequency energy was examined for efficacy and safety in a two-stage experimental study. Eleven mongrel dogs were treated via the bladder neck and prostatic urethra using a specially designed cathether through which needle antennas were advanced into the prostatic tissue. A radiofrequency energy source was connected to the catheter and used to create tissue ablation. In the first 5 dogs this was found to be feasible. Necrotic lesions were created around the needle antennas. Typically, lesions were 1 cm in diameter and conical in shape. The actual size of the lesion was directly related to power level used, time of ablation and length of needle deployment. In the next 6 dogs temperatures were simultaneously measured in the prostatic urethra and rectum. The dogs were sacrificed 0, 2, 2, 14, 28 and 30 days following the experiments and the bladder, prostate and anterior rectal wall were removed en bloc and examined macroscopically and histopathologically for any changes. It was found that urethral temperatures increased to 46.1°C on the average while rectal temperature did not rise during the entire experiment. The lesions found in the prostate were similar to those found in the first 5 dogs. No macroscopic or histopathologic changes were noted at the bladder base, anterior rectal wall or in the distal prostatic urethra. It was concluded that prostatic tissue ablation in the canine model can be achieved safely and could justify the start of human trials.