Do you know that electrical and chemical signals are used by our nerve and muscle cells to communicate with one another? Our heartbeat is likewise controlled by regular electrical signals.
The sinoatrial node (SA node), a collection of cells in the right atrium of the heart, transmits these signals, which travel through the heart muscle as minute electrical impulses. As a result, the heart’s atria contract before the ventricles do.
On the surface of our skin, we can also measure how these signals travel through the heart. These variations in electrical signals—or, more precisely, voltage—on various sections of skin are measured by a device called a Holter monitor and graphed. An electrocardiogram is a name given to the resulting ECG graph.
