Saline infusion markedly reduces impedance and improves efficacy of pulmonary radiofrequency ablation

Radiofrequency ablation (RFA) is a relatively new technique that has been investigated for the treatment of lung tumors. We evaluated for the first time the in vivo use of saline infusion during radiofrequency ablation of sheep lung. We performed RFA on 5 sheep using open and closed chest RFA and the RITA starburst XL and Xli probes using saline infusion with the Xli probe. The impedance and volume of ablation were compared. A total of 16 ablations were produced, 5 percutaneously and 11 open. The impedance during percutaneous and open RFA without saline infusion was 110 +/- 16.2 and 183.3 +/- 105.8 Omega, respectively. With the saline infusion the impedance was 71.3 +/- 22Omega and 103.6 +/- 37.5Omega. The effect of this was a significantly larger volume of ablation using the saline infusion during percutaneous RFA (90.6 +/- 23 cm(3) vs 10.47 +/- 2.9 cm(3), p = 0.01) and open RFA (107.8 +/- 25.8 cm(3) vs 24.9 +/- 19.3 cm(3), p = 0.0002). Saline infusion during RFA is associated with lower impedance, higher power delivery and larger lesion size.