Comparison of methods in approximation of blood flow in finite element models on temperature profile during RF ablation

Abstract

The difficulties in controlling factors that affect lesion size in vitro and in vivo suggest that a theoretical approach may be advantageous. Due to complexities in describing flow velocity field in the equations, heat lost to convection due to blood flow was approximated by film boundary condition at blood/tissue and blood/electrode interfaces in the existing models in literature. Experimental data has shown that the temperature distribution is sensitive to convection. However, no modeling work has been reported on either alternative approaches or the impact of film boundary condition on temperature distribution. Here, the authors introduce body flux for convection in blood and compare the results with film boundary condition and with no convection. After 60 seconds of 10 W RF energy delivery, lesion size remains almost the same by using either body flux or film boundary condition. However, the difference in maximum temperature in tissue and electrode temperature may have implication in temperature controlled RF ablation. The maximum temperature in tissue varies from the surface of electrode into one millimeter deep in tissue due to convection.