Clinicians have a variety of diagnostic methods available for evaluating a child with an arrhythmia. The ECG and Holter ECG remain the cornerstones for a good diagnostic and a correct management. Many pediatric cardiologists have some experience in Holter ECG interpretation, but many are still uncertain about their ability to recognize normal variants and pathological rhythms. This book is written specifically for pediatric cardiologists and provides a short and practical review of the issue. Following a brief introduction of the theoretical basis of the Holter ECG, the chapters give a systematic method to interpretation of ECG signals. Several print screens from the different softwares are included to assist users in more confidently diagnosing arrhythmias. The book's second part provides a comprehensive collection of real-life cases and Holter ECG tracings in an easy-to-use manner. The cases cover the most common arrhythmias seen in pediatrics and will assist build the skills needed to analyse the Holter ECG quickly and effectively in both infants and older children.