The Cardiac Electrical System - How the Heart Beats

Figure 5: This figure shows the electrical impulse spreading throughout the right and left ventricles, causing these chambers to contract. As the electrical signal travels through the ventricles, it generates the “QRS complex” on the ECG. The QRS complex is indicated by the solid purple line on the ECG below.

In this manner, the electrical system of the heart causes the heart muscle to contract, and causes it to contract in a coordinated manner, maximizing the efficiency of the beating heart.