Nonuniform heating patterns of commercial electrodes for radiofrequency catheter ablation

Previous investigations of the biophysics of myocardial ablation using radiofrequency energy have focused mainly on the electrode-myocardial interface. Relatively little has been written about the overall function of commercial electrodes used for ablation. The purpose of this study was to evaluate the heating patterns of several commercial electrodes used for myocardial ablation.

The specific absorption rate, a unit of measure proportional to the initial 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 each electrode. These measurements were combined to form a specific absorption rate pattern, which reflected the spatial pattern of energy deposition from the electrode. There was significant nonuniformity of the specific absorption rate pattern of each electrode evaluated. The proximal edge of the electrode and the curvature of the distal portion of the electrode were two sites of accentuated heating relative to the remaining portions of the electrode. The magnitude of this nonuniformity was similar between the 4-mm length electrodes of different manufacturers, but increased progressively in larger (5- and 8-mm length) electrodes.

The heating patterns of commercial electrodes used for myocardial ablation are nonuniform. These data have implications for electrode design and utilization.