The electrocardiogram (ECG) is a diagnostic test that records the electrical activity of the heart to test for any kind of pathology. It also constitutes one of the most important tools to find out and evaluate most of the cardiac conditions. Also, electrocardiography provides an invaluable tool for the diagnosis of the growth of the heart chambers (atria and ventricles). In many cases, the diagnosis of congenital heart diseases comes from the characteristic ECG graphic. In fact, the ECG provides important data for the evaluation of more than 80% of heart diseases.