Echocardiogram (ECG) is a simple, useful and practical diagnostic test for cardiac diseases. ECG helps physicians to make the correct diagnosis, evaluate myocardial function and monitor the efficacy of treatment. This book, in short, describes most of the available changes in ECG pattern in different heart ailments along with possible interpretations, which are helpful for medical students and practicing physicians. Now a days, a proper clinical diagnosis is impossible without ECG. So, this is a widespread application not only in cardiology but also in other branches of medical sciences. This book is a culmination of knowledge gathered from standard textbooks or journals and authors’ own experience. This book consists of 16 chapters, which discusses about the introduction, anatomy and physiology, electrocardiographic leads, essential basic electrocardiogram principles, normal electrocardiogram, axis and vectors, abnormalities of wave intervals and segments, hypertrophy, arrhythmias: disorders of the cardiac rhythms, heart block, myocardial ischemia, injury, infarction, drugs and electrolytes effects and miscellaneous conditions. Congenital heart diseases, pacemakers and exercise tolerance test, and echocardiogram interpretation and diagnosis also discussed in this book.