"The ventricles then recover their normal electrical state (shown as the T wave on the EKG). The muscle stops contracting to allow the heart to refill with blood. This entire process continues over and over with each new heartbeat. The animation below shows how your heart's electrical system works and how an EKG records your heart's electrical activity. Click the ""start"" button to play the animation. Written and spoken explanations are provided with each frame. Use the buttons in the lower right corner to pause, restart, or replay the animation, or use the scroll bar below the buttons to move through the frames. The animation shows how an electrical signal moves through your heart and how an EKG records your heart's electrical activity."