This book describes in detail the specific aspects of ECG during childhood and adolescence, pursuing an accessible, didactic and easy-to-read approach. Instructive, self-contained and intelligently written, it succeeds in making this diagnostic tool, the interpretation of which is especially complex in younger patients, more comprehensible, while also offering a sound and extensive reference guide for all those who diagnose young patients with electrocardiography. Though ECG produces a relatively simple set of readings, its interpretation and diagnosis are complex. If misinterpreted, a  butterfly effect  of hidden, often neglected heart signals can lead to important and sometimes devastating consequences.