COMPARISON OF GOLD VERSUS PLATINUM-ELECTRODES ON MYOCARDIAL LESION SIZE USING RADIOFREQUENCY ENERGY

During radiofrequency (RF) catheter ablation of arrhythmias, temperatu res that approach 100 degrees C cause a coagulum to form on the ablati on electrode that results in an increase in electrical impedance and p revents further energy delivery. Since gold has nearly four times the thermal conductivity as platinum, the metal commonly used, it was post ulated that gold tip electrodes could deliver more power and produce d eeper lesions because of ifs greater heat dissipation from the electro de-tissue interface to the circulating blood. To test this hypothesis, RF energy was applied to fresh bovine ventricular myocardium using 6 French catheters with 2-mm long distal electrodes made from gold or pl atinum. Similar studies were also conducted using 7 French catheters w ith 4-mm long distal electrodes. Maximum lesion depth was defined as t hat produced with She level of energy just below that causing an imped ance rise. A maximum lesion depth of 6.2 +/- 0.7 mm (mean +/- SD) was obtained with the gold 2-mm electrode and 4.7 +/- 0.5 mm with the plat inum electrode (P = 0.003). The 4-mm gold electrode produced a maximum lesion depth of 7.2 +/- 1.4 mm, while a catheter with a 4-mm platinum electrode caused a maximum lesion depth of 5.8 +/- 0.7 mm (P = 0.05). We conclude that deeper lesions should be able to be made when RF ene rgy is delivered to a gold rather than platinum tip electrode.