Prolonged QT interval and sudden infant death--report of two cases.

In the two cases where infants died suddenly and unexpectedly the electrocardiogram (ECG) of a younger sibling (case 1) and of a living twin (case 2) led to the suspicion that the two infants could have died from long QT syndrome (LQTS). In case 1, a His bundle (HB) dispersion and a pronounced hypoplasia of the right external nucleus arcuatus were detected. In case 2, a severe interstitial pneumonia and an accompanying mild myocarditis were found by histology. Molecular genetic investigations of the coding regions of the genes, HERG, KVLQT1 and SCN5A gave no indication for the mutations, thus, affecting related myocardial ion channels as possible sources of inhomogeneity of repolarisation. Since a molecular genetic deviation could not yet be elaborated the possible role of related disturbance remains unknown.