The heartbeat is controlled by the electrical system of the heart (Fig. 1). This system is made of several parts that tell the muscle of the heart when to contract. The SA node starts the heartbeat causing the atria, or upper chambers of the heart, to contract. The signal then travels through the AV node, the Bundle of His, Bundle Branches, and Purkinje fibers. This causes the ventricles, the lower chambers of the heart, to contract. The flow of electrical signals produces a normal heartbeat (Fig. 2). Normal heartbeats can be seen on an electrocardiogram, or ECG.
Atrial Flutter is a type of heart arrhythmia, or irregular heartbeat. In atrial flutter, abnormal electrical signals circulate in the heart’s upper chambers, or atria, which causes the rhythm of the lower chambers to be fast (Fig. 3). Because contractions are not timed as in the normal heartbeat, the heart does not pump blood as effectively to the rest of the body. Irregular heartbeats can be seen on an electrocardiogram, or ECG (Fig. 4).
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