A Comparison of the Size and Shape of Radiofrequency Lesions Produced by Different Temperatures Using Straight and Curved Electrodes

Lee, Kee Heon; Yun, Seon Hye; Kim, Hyun Ju; Jung, Bae Hee; Lim, So Young; Shin, Keun Man; Hong, Soon Yong

Abstract

BACKGROUND: Understanding the electrophysiology of radiofrequency (RF) lesions and determining the size and shape of RF lesions is important for reducing side effects when applied to patients in a clinical setting. We compared the shape and size of RF thermocoagulation produced by straight and curved 20-gauge electrodes and considered its application in clinical settings.
METHODS
The white from a fresh hen's egg was warmed to 37oC and placed in a rectangular glass container. Straight and curved 20-gauge electrodes were immersed. The transparency of the egg white and the glass container made it possible to photograph the changes in size of the RF lesions over time. We applied thermocoagulation for 60 seconds at 70, 80, and 90oC. Photographs were taken at 60 seconds. We measured the maximal size of the lesions. A two-way statistical analysis of variance was performed.
RESULTS
The thermocoagulations were started at the junction of the insulated and uninsulated portion of the electrode and did not extended beyond the tip. The thermocoagulation size was 4.2 +/- 0.8 at 70oC, 6.1 +/- 2.9 at 80oC and 6.1 +/- 1.9 at 90oC using the 20-gauge, 10 mm active tip, straight electrode and 4.5 +/- 1.1 at 70oC, 7.2 +/- 1.9 at 80oC and 7.9 +/- 2.7 at 90oC using the 20-gauge, 10 mm active tip, curved electrode. There was no observable difference in the size of the lesions produced by the straight and curved electrodes.
CONCLUSIONS
We found that temperature was the more important factor in determining lesion size. When the temperature setting is the same, lesions produced by straight and curved electrode of the same gauge are also same size. Therefore the choice of straight or curved electrode should be made to optimize ease of handling and ensure proper location of the electrode tip.