title: [Sudden infant death--the QT interval in ECG and bradyarrhythmias].
abstract: Prolongation of ventricular repolarization, as evidenced from an increased QT-interval, makes the ventricles more susceptible to fibrillation. The theory has previously been advanced that some cases of sudden infant death syndrome may be due to a non-hereditary QT-prolongation, resulting in fibrillation and cardiac death. This theory has been seriously doubted, since in subsequent long series of recordings in newborns the QT-interval has been found normal at rest. However, the QT-theory has recently been revived by a report that in some babies with sudden infant death syndrome the ability to shorten the QT-interval as the heart rate increases is impaired, an observation which is consistent with the QT-theory. The present experiments on infant and adult rodents have shown that during the innate fear paralysis reflex, elicited by a variety of frightening stimuli of a type that commonly occur during ordinary daily life, the QT-interval may be transiently prolonged and is usually associated with bradycardia and changes of the ST-segment and T-wave. The fear paralysis reflex has previously been proposed as a triggering mechanism for SIDS. These findings lend support both to the fear paralysis theory and the QT-theory. The reflex may represent an external cause of QT-prolongation which adds to the intrinsic impairment of repolarization resulting in a condition which favours ventricular fibrillation. A second unfavourable intrinsic factor is chronic hypoxia.
authors.forename: B
authors.initials: B
authors.lastname: Kaada
mesh_terms: D001145:Arrhythmias, Cardiac / Q000150:complications*; D001919:Bradycardia / Q000150:complications / Q000503:physiopathology; D004562:Electrocardiography; D006339:Heart Rate; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008133:Long QT Syndrome / Q000150:complications*; D013398:Sudden Infant Death / Q000503:physiopathology*
vernacular_title: Krybbedød--QT-intervallet i EKG og bradyarytmier.