Gold-tip electrodes--a new "deep lesion" technology for catheter ablation? In vitro comparison of a gold alloy versus platinum-iridium tip electrode ablation catheter.

Gold-tip electrodes. Radiofrequency (RF) catheter ablation is widely used to induce focal myocardial necrosis using the effect of resistive heating through high-frequency current delivery. It is current standard to limit the target tissue-electrode interface temperature to a maximum of 60-70 degrees C to avoid char formation. Gold (Au) exhibits a thermal conductivity of nearly four times greater than platinum (Pt-Ir) (3.17 W/cm Kelvin vs 0.716 W/cm Kelvin), it was therefore hypothesized that RF ablation using a gold electrode would create broader and deeper lesions as a result of a better heat conduction from the tissue-electrode interface and additional cooling of the gold electrode by "heat loss" to the intracardiac blood. Both mechanisms would allow applying more RF power to the tissue before the electrode-tissue interface temperature limit is reached. To test this hypothesis, we performed in vitro isolated liver and pig heart investigations comparing lesion depths of a new Au-alloy-tip electrode to standard Pt-Ir electrode material. Mean lesion depth in liver tissue for Pt-Ir was 4.33+/-0.45 mm (n=60) whereas Au electrode was able to achieve significantly deeper lesions (5.86+/-0.37 mm [n=60; P<0.001]). The mean power delivered using Pt-Ir was 6.95+/-2.41 W whereas Au tip electrode delivered 9.64+/-3.78 W indicating a statistically significant difference (P<0.05). In vitro pig heart tissue Au ablation (n=20) increased significantly the lesion depth (Au: 4.85+/-1.01 mm, Pt-Ir: 2.96+/-0.81 mm, n=20; P<0.001). Au tip electrode again applied significantly more power (P<0.001). Gold-tip electrode catheters were able to induce deeper lesions using RF ablation in vitro as compared to Pt-Ir tip electrode material. In liver and in pig heart tissue, the increase in lesion depth was associated with a significant increase in the average power applied with the gold electrode at the same level of electrode-tissue temperature as compared to platinum material.