Introduction

Cardiac disease is one of the major causes of sudden and unexpected natural death in children, adolescents, and young adults. Myocarditis, hypertrophic cardiomyopathy, congenital aortic stenosis, channelopathies, and cyanotic congenital heart disease with pulmonary obstruction are among the most common medical conditions that cause sudden death in this age group. This contrasts with older adults, in whom atherosclerotic coronary artery disease is a far more usual finding. Additionally, there are many rarer entities that may also result in sudden cardiac decompensation and death in the young. Determination of the precise incidence of a number of these rarer entities is difficult because of subtle autopsy findings and variable standards of postmortem investigation. Death is usually initiated by tachy- or bradycardias resulting in disorganized myocardial pumping, followed by hypotension and cellular hypoxia/ischemia.

A number of cases of sudden death are associated with exercise and may have been heralded by palpitations, dyspnea, chest pain, or syncope, although this is not always the case. The risk of sudden death in young athletes is 0.3–1 per 100,000 athlete–years. Cardiac syncopal episodes may be accompanied by seizure activity lasting 10–20 seconds, so called Stokes–Adams syndrome, which may incorrectly focus attention on possible neurological disease. Causes of sudden cardiac death in the young are listed in Table 5.1; complex gene linkages have now been established for many of these. Rowlatt, Rimoldi, & Lev have described measurements of normal cardiac parameters in children.