An electrocardiogram, also called an EKG, is a noninvasive test used to monitor the electrical activity of your child's heart and to help diagnose many types of common heart problems. Each beat of the heart is activated by an electrical impulse produced from special cells in the right upper chamber of your heart. An electrocardiogram records these electrical signals as they travel through your heart. Your doctor may use an electrocardiogram to detect abnormalities in your heart rhythm or some heart defects. The results are often available the same day.