the atrioventricular node or av node is a part of the electrical conduction system of the heart that coordinates the top of the heart. it electrically connects the atria and ventricles. the av node lies at the lower back section of the interatrial septum near the opening of the coronary sinus, and conducts the normal electrical impulse from the atria to the ventricles. the av node is quite compact (~1 x 3 x 5 mm).