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Congenital Long QT Syndrome Type 8 Characterized by Fetal Onset of Bradycardia and 2:1 Atrioventricular Block

Authors :
Donghoon Joo
Hyoung Doo Lee
Taehong Kim
Hoon Ko
Joung-Hee Byun
Source :
Neonatal Medicine, Vol 28, Iss 1, Pp 59-63 (2021)
Publication Year :
2021
Publisher :
Korean Society of Neonatology, 2021.

Abstract

An important, albeit rare, cause of fetal bradycardia is long QT syndrome (LQTS). Congenital LQTS is an ion channelopathy caused by mutations in genes encoding cardiac ion channel proteins. Fetal onset of LQTS imposes high risk of life-threatening tachyarrhythmias and sudden cardiac death. Here, we report the case of a female newborn with fetal onset of bradycardia and a 2:1 atrioventricular (AV) block. After birth, a 12-lead electrocardiogram (ECG) revealed bradycardia with QT prolongation of a corrected QT (QTc) interval of 680 ms and pseudo 2:1 AV block. Genetic testing identified a heterozygous Gly402Ser (c.1204G>A) mutation in CACNA1C, confirming the diagnosis of LQTS type 8 (LQT8). The patient received propranolol at a daily dose of 2 mg/kg. Mexiletine was subsequently administered owing to the sustained prolongation of the QT interval and pseudo 2:1 AV block. One week after mexiletine inception, the ECG still showed QT interval prolongation (QTc, 632 ms), but no AV block was observed. There were no life-threatening tachyarrhythmias in a follow-up period of 13 months.

Details

Language :
English, Korean
ISSN :
22879412, 22879803, and 92044166
Volume :
28
Issue :
1
Database :
Directory of Open Access Journals
Journal :
Neonatal Medicine
Publication Type :
Academic Journal
Accession number :
edsdoj.0bd95f9204416694d7883f1c0986ca
Document Type :
article
Full Text :
https://doi.org/10.5385/nm.2021.28.1.59