Atrioventricular node Atrioventricular node 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, which conducts the normal electrical impulse from the atria to the ventricles. The AV node is quite compact (~1 x 3 x 5 mm). The AV node lies at the lower back section of the interatrial septum near the opening of the coronary sinus, which conducts the
Artificial cardiac pacemaker which is the mode of choice when atrioventricular conduction is intact but the natural pacemaker the sinoatrial node is unreliable – sinus node disease (SND) or sick sinus syndrome. Where the problem is atrioventricular block (AVB) the pacemaker is required to detect (sense) the atrial beat and after a normal delay (0.1–0.2 seconds) trigger a ventricular beat, unless it has already happened – this is VDD mode and can be achieved with a single pacing lead with electrodes in the right atrium (to sense) and ventricle (to sense and pace). These modes AAIR and VDD are unusual in the US