Prolongation of the QT interval is the cause of about 10% cases of sudden infant death syndrome (SIDS) in newborns. Neonatal electrocardiographic screening is highly cost-effective and it may permit the early identification of infants at risk for SIDS.
Long QT syndrome (LQTS) is an electrophysiological disorder characterized by a lengthening of the repolarization phase of the ventricular action potential (prolongation of the QT interval on the basis of a surface EKG).
The effectiveness of a surface EKG as a screening method for LQTS in new-borns was addressed by the present report.
- The major changes in the paediatric EKG occur in the first year of life with the majority of normal adult values being abnormal in the newborn. Likewise, many normal newborn values and patterns would be abnormal in the adult.
- The QT duration may change over time so it is recommended repeating EKG in those infants with a prolonged QTc on the first EKG. To decrease the rate of false-positives, implementation of EKG screening at days 15 to 25 was advised.
- 10 to 15 % of SIDS causes are due to LQTS and the early treatment is life-saving. Medications, use of automatic implantable defibrillators, and modifications of activities have been associated with significant reduction in risk of sudden death.
- EKG screening and subsequent molecular testing of all neonates with QTc morethan 440 msec could probably identify the majority of LQTS cases, including the ones that will not die of SIDS, but who are still at risk of sudden death at a young age.
- A prolonged QT interval on days 3 to 4 of life was associated with a significantly higher risk of Sudden infant death syndrome (SIDS).
- The newborns with QTc values over 470 msec often normalize by themselves in the first month of life, a phenomenon is called as “spurious QTc”.
- A QTc close to 500 msec implies a clear abnormality even taking into account potential measurement errors.
It is established that newborns with prolonged QTc (greater than 440 msec) on the fourth day of life have an increased risk for sudden death.