Abnormal cardiac repolarization renders the heart susceptible to lethal ventricular
tachyarrhythmias, increasing the risk of sudden cardiac death in all ages; however,
little is known about the incidence and etiology of T-wave abnormalities in utero.
In this study, magnetocardiography was used to better define fetal T-wave characteristics,
including the QT interval in the normal fetus, and to characterize T-wave abnormalities
in the fetus with arrhythmia. The QT interval and T-wave alternans were assessed from
magnetocardiographic recordings obtained at 14 to 39 weeks’ gestation from 120 fetuses.
Of these fetuses, 78 were from uncomplicated pregnancies and 42 had various forms
of fetal arrhythmia (supraventricular tachycardia in 14, congenital atrioventricular
block in 17, long QT syndrome with Torsades de pointes in 1, ventricular tachycardia
in 2, sinus bradycardia in 4, and bradycardia due to blocked premature atrial contractions
in 4). Although the corrected QT interval in normal sinus rhythm was accurately described
by Bazett’s formula, the corrected QT interval in fetal arrhythmia exhibited a systematic
deviation at heart rate extremes. The dependence of the QT interval on the RR interval
in arrhythmia was approximately described by QT∝RR0.8. T-wave alternans was detected in 7 fetuses with arrhythmia, often in association
with QT prolongation, suboptimal outcome, or fetal demise. The results of our study
have demonstrated that QT-interval abnormalities exist and can be detected in fetal
patients. The potential importance of T-wave assessment in the fetus with cardiac
arrhythmia was evidenced by the high incidence of marked QT prolongation and T-wave
alternans in the fetuses with suboptimal outcomes.
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Article info
Publication history
Published online: June 23, 2006
Accepted:
March 6,
2006
Received in revised form:
March 2,
2006
Received:
January 5,
2006
Footnotes
This study was supported by Grant R-01 HL63174 from the National Institutes of Health, Bethesda, Maryland.
Identification
Copyright
© 2006 Elsevier Inc. Published by Elsevier Inc. All rights reserved.
