NONUNIFORM HEATING PATTERNS OF COMMERCIAL ELECTRODES FOR RADIOFREQUENCY CATHETER ABLATION

Introduction: Previous investigations of the biophysics of myocardial ablation using radiofrequency energy have focused mainly on the electr ode-myocardial interface. Relatively little has been written about the overall function of commercial electrodes used for ablation, The purp ose of this study was to evaluate the heating patterns of several comm ercial electrodes used for myocardial ablation. Methods and Results: T he specific absorption rate, a unit of measure proportional to the ini tial rate of rise of the temperature at the electrode-tissue interface and reflecting the energy deposition from the electrode, was measured during radiofrequency energy application at multiple points around ea ch electrode, These measurements were combined to form a specific abso rption rate pattern, which reflected the spatial pattern of energy dep osition from the electrode, There was significant nonuniformity of the specific absorption rate pattern of each electrode evaluated, The pro ximal edge of the electrode and the curvature of the distal portion of the electrode were two sites of accentuated heating relative to the r emaining portions of the electrode, The magnitude of this nonuniformit y was similar between the 4-mm length electrodes of different manufact urers, but increased progressively in larger (5- and 8-mm length) elec trodes. Conclusions: The heating patterns of commercial electrodes use d for myocardial ablation are nonuniform. These data have implications for electrode design and utilization.