– ATX-II TFA, a specific Na+ channel modulator toxin, is derived from the venom of the sea anemone (Anemonia sulcata). This compound impedes the inactivation of Na+ channels and has been associated with arrhythmogenesis in the pulmonary vein and atrial fibrillation [1] [2]. It interacts with halothane, caffeine, and ryanodine in this modulation.