Analysis of the variables that affect electrode and tissue temperature during RF ablation in a finite element analysis model

Blood coagulation, char formation, and microexplosions have been problems with RF ablation procedures which limit the formation of linear and transmural lesions. Monitoring the temperature (T) on the ablation electrode has been shown to alleviate some of these problems. This study was to investigate this relationship between the minimum tissue T (maxT) and electrode T during low and high power delivery. A 3D finite element model of a tank was built with convection from blood cooling. A 8 mm long solid metal tip was placed along the interface of blood and myocardium. The model results indicate that electrode T does not correlate well with maxT. The difference between maxT and electrode T was dependent on the power setting and the time of ablation. Lower power setting created larger lesion, more uniform temperature distribution and smaller difference between ET and maxT.