Sudden infant death - Sudden cardiac death?

The unexplained and sudden nature of death ascribed to sudden infant death syndrome (SIDS) makes an arrhythmic cause an attractive hypothesis. Over 30 years, a number of infants have been documented to have had a Long QT interval on an ECG prior to death, and a few have had documented Torsade-de-Pointes. The QT interval is normally longest at the peak time of SIDS (2-3 months). Mutations in the long QT genes have recently been identified in about one third of a series of SIDs cases; whether they are truly pathogenic is uncertain. The commonest post-mortem finding of sub-pleural petechial haemorrhage is much more suggestive of an asphyxial death, and the association with maternal smoking supports a respiratory cause. Infants who lie on their back have a greatly reduced risk of SIDS- suggesting that heat stress may be a factor (they don't get stuck under the sheets). A minority of SIDS is due to Long-QT syndrome, perhaps heat or asphyxial stress is a trigger for ventricular tachycardia.