Congenital heart disease is the most common serious congenital defect. It occurs in ~1% of all live births, and annually about 1.5 million children are born with congenital heart disease. (A similar number have bicuspid aortic valves, but these seldom cause problems in childhood.) Given the high potential early mortality and morbidity of these diseases, any book such as this one that improves the effectiveness of treatment will make a major contribution to world health. Neonatal cardiology is concerned mainly with congenital heart disease. The period of transition from fetus to neonate is often difficult, and congenital or acquired disease at this age may, for many reasons, be more difficult to manage than at older ages. It is not surprising, therefore, that the highest mortality in children with congenital heart disease who are not treated occurs in the neonatal period. What is surprising is that so few books have concentrated on this critical period. This third edition of Neonatal Cardiology has gone a long way to correcting the deficiency. With the advances in imaging methods, diagnostic cardiac catheterization has been replaced by echocardiography, CT, and MRI. As a result, the emphasis today is placed on anatomic abnormalities rather than on their physiological consequences, even though it is these consequences that often determine the outcome. The authors of this book, basing their work on the groundbreaking studies by Dr. Abraham Rudolph of abnormal fetal development and the physiological changes due to congenital heart disease, have shown how understanding the physiology as well as the anatomy of these lesions improves our ability to treat these patients. In this third edition, Drs. Teitel, Mahony, and Artman have updated and expanded what was in the second edition with added information about myocytes, arrhythmias, and genetics. In addition, they have enlisted Dr. Gittenberger de Groot and her colleagues to discuss current concepts of cardiac embryology.