Embodiments of the invention provide an ablation apparatus for ablating target tissue adjacent pulmonary veins of a patient. The ablation apparatus can include a tube capable of being advanced around the pulmonary veins to form a loop. The tube can receive or include electrodes to ablate target tissue. Some embodiments provide a loop ablation device, which may include a cannula and two or more electrode rods carrying two or more bipolar electrodes. The electrode rods can be advanced through the distal ends toward the proximal ends of the loop and toward the target tissue. The bipolar electrodes can receive energy to ablate the target tissue. The bipolar electrodes may be surrounded by the liquid within the cannula while ablating the target tissue. The loop ablation device can further include a rotating grasping mechanism coupled to the electrode rods.