Altered Cardiac Repolarization in Some Victims of Sudden Infant Death Syndrome

Dror Sadeh, Daniel C. Shannon*, Shimon Abboud, J. Philip Saul, Solange Akselrod, Richard J. Cohen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

33 Scopus citations


Abnormal prolongation of cardiac repolarization, as reflected by a long QT interval with respect to the RR interval on the electrocardiogram, is known to be associated with ventricular tachyarrhythmias. To test the hypothesis that prolonged cardiac repolarization may characterize some babies who die of sudden infant death syndrome (SIDS), we studied the dependence of the QT interval on the preceding RR interval in 10 babies with SIDS and 29 healthy control babies. We analyzed approximately 5000 pairs of QT and RR intervals in each subject over a wide range of RR intervals. We found that the QT intervals demonstrated less dependence on the preceding RR intervals in 5 of 10 babies who subsequently died of SIDS than in normal controls. No ventricular arrhythmias were observed, however, during the six-hour recording period. Our data suggest that in some babies with SIDS the ability to shorten the QT interval as the heart rate increases is impaired. These observations are consistent with the hypothesis that relatively prolonged cardiac repolarization may predispose such babies to ventricular arrhythmias. (N Engl J Med 1987; 317:1501–5.), THE ability of the autonomic nervous system and heart to alter the duration of cardiac repolarization and consequently the QT interval in response to changes in the heart rate (i.e., the RR interval) is an essential component of cardiovascular control. Decreases in the RR interval that are not accompanied by an appropriate decrease in the QT interval will eventually lead to either blocked depolarizations or the “R on T” phenomenon, which may predispose to ventricular reentry and fibrillation. A prolonged QT interval with respect to the RR interval may reflect an abnormality in the repolarization process. Such a mechanism has…

Original languageEnglish
Pages (from-to)1501-1505
Number of pages5
JournalNew England Journal of Medicine
Issue number24
StatePublished - 10 Dec 1987
Externally publishedYes


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