This illustrated text teaches electrophysiology and cardiology fellows-in-training the concept of connecting ventricular arrhythmias’ QRS morphology with the arrhythmia site of origin. Thirty case studies, including multimodality imaging and anatomy data, illustrate the precise locations of the sites of origin of different ventricular arrhythmias. Mapping approaches are discussed, with an emphasis on how the 12-lead ECG helps to identify critical sites of the arrhythmias. Illustrated with 106 figures that include 12-lead ECGs, intracardiac ECG tracings, and electroanatomical maps that are complemented by reconstructed intracardiac echo images.