To understand the underlying causes of heart rhythm problems, such as tachycardia, it is essential to grasp the heart's complex electrical system. The heart consists of four chambers: two upper chambers (atria) and two lower chambers (ventricles). Your heartbeat is regulated by the sinus node, located in the right atrium, which functions as the heart's natural pacemaker. The sinus node generates electrical impulses that initiate each heartbeat. These impulses spread across the atria, causing the atrial muscles to contract and pump blood into the lower chambers (ventricles). The electrical impulses then reach a cluster of cells called the atrioventricular (AV) node. The AV node slightly delays the signals before transmitting them to the ventricles. This delay allows sufficient time for the ventricles to fill with blood. Once the electrical impulses reach the ventricular muscles, they contract, causing blood to be pumped to the lungs or the rest of the body. Any disruption in this well-synchronized system can cause the heart to beat too fast (tachycardia), too slow (bradycardia), or with an irregular rhythm.