Neonatal long QT syndrome and sudden cardiac death.

Neonatal sudden cardiac death most often results from cardiac electrical diseases, cardiomyopathies, or sudden infant death syndrome. In infants without a known premortem diagnosis or abnormalities identified at autopsy, sudden infant death syndrome accounts for the vast majority of sudden deaths. Potential cardiac causes of some sudden infant death syndrome cases may include malignant brady- or tachyarrhythmias and congenital long QT syndrome. The possible mechanisms include abnormal brain stem respiratory control of arousal, dysautonomia and malignant cardiac bradyarrhythmias or tachyarrhythmias. Screening for neonatal sudden cardiac death may not be feasible, but hopefully through careful review of history, physical examination, and family health history, and judicious diagnostic testing, can the risk of cardiac sudden death be reduced. Further comprehension of the genetic basis of inherited arrhythmia disorders may help elucidate the mechanisms of arrhythmogenesis and etiologies of sudden infant death. Prevention and treatment of these disorders may also be improved through more detailed understanding of the molecular basis of cardiac electrical pathophysiology.