This book dedicates the first seven chapters to cardiac electrophysiological dysfunction that can lead to ventricular fibrillation and sudden death. The next six chapters expand the topics of sudden death to other causes. Brugada Syndrome is the top cause of non-traumatic sudden death in young males of Southeastern Asian and southern European origins. Chapters One and Two review extensively the history and current status, mechanisms of arrhythmias, and related gene mutations in Brugada Syndrome, and discuss gaps in the current knowledge. Chapter Three presents clinical studies on the A1180V and R1193Q mutations of the cardiac sodium channel gene, SCN5A. The authors identified R1193Q mutation in 12.8%-16% of a healthy Chinese population. This result prompted the question of whether SCN5A mutations are still the top genetic bases of Brugada and long QT syndromes. Chapters Four, Five and Seven discuss the pathophysiology causes, risk factors, predictors, prevention, and possible therapeutical strategies of sudden cardiac death. Chapter Six reviews the scope and causes of sudden cardiac death in athletics.Chapter Seven is dedicated to the roles of electrical cardiac systole in sudden death. Chapter Eight reviews sudden death related to cardiac and brain tumours, pulmonary tumour embolism, asphyxia, massive exsanguinations, and their pathophysiology. Chapter Nine summarises the pathophysiology of sudden death caused by myocardial tuberculosis. Chapter Ten introduces pathophysiology of sudden death during hot baths in deep bathtubs, which occurs frequently in elderly people in Japan. Chapter Eleven discusses air pollution as a trigger of sudden death. Chapter Twelve presents biochemical, cytological and histopathological examination of sudden unexpected death in infancy. The last chapter of the book, Chapter Thirteen, reviews post-mortem cardiac markers in different body fluids and their application in forensic pathology diagnosis of sudden cardiac death. In combination, these chapters cover a broad range of topics about sudden death.