The effect of changing the size and position of the anode and cathode during direct current Transcatheter Electrocoagulation (TCEC) was evaluated in dogs. The results showed that there was no difference in the time required for vessel occlusion when the size and position of the electrodes were changed. However, there were differences noted in the amount of voltage needed to maintain the constant current. Based on these results, for TCEC we recommend positioning the largest possible guidewire anode against the vessel wall. The cathode should be a highly lubricated sponge covered Bovie ground plate.