cardiovascular disorders
Electrocardiography
Introduction
The standard electrocardiogram (ECG) provides 12 different vector views of the heart’s electrical activity as reflected by electrical potential differences between positive and negative electrodes placed on the limbs and chest wall. Six of these views are vertical (using frontal leads I, II, and III and limb leads aVR, aVL, and aVF), and 6 are horizontal (using precordial leads V1, V2, V3, V4, V5, and V6). The 12-lead ECG is crucial for establishing many cardiac diagnoses (see table), including Overview of Arrhythmias None Atrial enlargement Conditions that predispose to syncope or sudden death (eg, Brugada Syndrome , Myocardial ischemia Ventricular hypertrophy (see table) For more information on ECG interpretation, see Diagnosis and 