Heart is established by the sinoatrial node, the heart's pacemaker. Here an electrical signal is created that travels through the heart, causing the heart muscle to contract. The sinoatrial node is found in the upper part of the right atrium near to the junction with the superior vena cava. The electrical signal generated by the sinoatrial node travels through the right atrium in a radial way that is not completely understood. It travels to the left atrium via Bachmann's bundle, such that the muscles of the left and right atria contract together. The signal then travels to the atrioventricular node. This
Bachmann's bundle found that clamping the muscular bundle of fibers that connects the atria caused a significant conduction delay. The Bachman's bundle receives its blood supply from the sinoatrial nodal artery (right, left or both). Besides Bachmann's bundle, the other three conduction tracts that constitute the "atrial conduction system" are known as the anterior, middle, and posterior tracts, which run from the sinoatrial node to the atrioventricular node, converging in the region near the coronary sinus. "Atrial automaticity foci" are within the atrial conduction system. The concentration of converging conduction tracts near the coronary sinus results in considerable automaticity activity originating in