Temperature-controlled and constant-power radio-frequency ablation: what affects lesion growth?

Radio-frequency (RF) catheter ablation is the primary interventional therapy for the treatment of many cardiac tachyarrhythmias. Three-dimensional finite element analysis of constant-power (CPRFA) and temperature-controlled RF ablation (TCRFA) of the endocardium is performed. The objectives are to study: (1) the lesion growth with time and (2) the effect of ground electrode location on lesion dimensions and ablation efficiency. The results indicate that: (a) for TCRFA: (i) lesion growth was fastest during the first 20 s, subsequently the lesion growth slowed reaching a steady state after 100 s, (ii) positioning the ground electrode directly opposite the catheter tip (optimal) produced a larger lesion, and (iii) a constant tip temperature maintained a constant maximum tissue temperature; (b) for CPRFA: (i) the lesion growth was fastest during the first 20 s and then the lesion growth slowed; however, the lesion size did not reach steady state even after 600 s suggesting that longer durations of energy delivery may result in wider and deeper lesions, (ii) the temperature dependent electrical conductivity of the tissue is responsible for this continuous lesion growth, and (iii) an optimal ground electrode location resulted in a slightly larger lesion and higher ablation efficiency.