3-DIMENSIONAL FINITE-ELEMENT ANALYSIS OF CURRENT-DENSITY AND TEMPERATURE DISTRIBUTIONS DURING RADIOFREQUENCY ABLATION

This study analyzed the influence of electrode geometry, tissue-electr ode angle, and blood flow on current density and temperature distribut ion, lesion size, and power requirements during radio-frequency ablati on, We used validated three-dimensional finite element models to perfo rm these analyses, We found that the use of an electrically insulating layer over the junction between electrode and catheter body reduced t he chances of charring and coagulation, The use of a thermistor at the tip of the ablation electrodes did not affect the current density dis tribution, For longer electrodes, the lateral current density decrease d more slowly with distance from the electrode surface, We analyzed th e effects of three tissue-electrode angles: 0, 45, and 90 degrees, Mor e power was needed to reach a maximal tissue temperature of 95 degrees C after 120 s when the electrode-tissue angle was 45 degrees, Consequ ently, the lesions were larger and deeper for a tissue-electrode angle of 45 degrees than for 0 and 90 degrees, The lesion depth, volume, an d required power increased with blood flow rate regardless of the tiss ue-electrode angle, The significant changes in power with the tissue-e lectrode angle suggest that it is safer and more efficient to ablate u sing temperature-controlled RF generators, The maximal temperature was reached at locations within the tissue, a fraction of a millimeter aw ay from the electrode surface, These locations did not always coincide with the local current density maxima, The locations of these hottest spots and the difference between their temperature and the temperatur e read by a sensor placed at the electrode tip changed with blood flow rate and tissue-electrode angle.