Magnesium sulfate-induced blocked premature atrial contractions resulting in fetal bradyarrhythmia

Takekazu Miyoshi, MD; Wataru Shimizu, MD; Takashi Noda, MD; Yoshinari Kobayashi, MD; Chizuko A. Kamiya, MD; Kaoru Yamanaka, MD; Reiko Neki, MD; Jun Yoshimatsu, MD; Shiro Kamakura, MD

doi:10.1016/j.joa.2013.11.002

Journal of Arrhythmia (Jun 2014)

Magnesium sulfate-induced blocked premature atrial contractions resulting in fetal bradyarrhythmia

Takekazu Miyoshi, MD,
Wataru Shimizu, MD,
Takashi Noda, MD,
Yoshinari Kobayashi, MD,
Chizuko A. Kamiya, MD,
Kaoru Yamanaka, MD,
Reiko Neki, MD,
Jun Yoshimatsu, MD,
Shiro Kamakura, MD

Affiliations

Takekazu Miyoshi, MD: Department of Perinatology and Gynecology, National Cerebral and Cardiovascular Center, 5-7-1 Fujishiro-dai, Suita, Osaka 565-8565, Japan
Wataru Shimizu, MD: Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center, Japan
Takashi Noda, MD: Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center, Japan
Yoshinari Kobayashi, MD: Department of Perinatology and Gynecology, National Cerebral and Cardiovascular Center, 5-7-1 Fujishiro-dai, Suita, Osaka 565-8565, Japan
Chizuko A. Kamiya, MD: Department of Perinatology and Gynecology, National Cerebral and Cardiovascular Center, 5-7-1 Fujishiro-dai, Suita, Osaka 565-8565, Japan
Kaoru Yamanaka, MD: Department of Perinatology and Gynecology, National Cerebral and Cardiovascular Center, 5-7-1 Fujishiro-dai, Suita, Osaka 565-8565, Japan
Reiko Neki, MD: Department of Perinatology and Gynecology, National Cerebral and Cardiovascular Center, 5-7-1 Fujishiro-dai, Suita, Osaka 565-8565, Japan
Jun Yoshimatsu, MD: Department of Perinatology and Gynecology, National Cerebral and Cardiovascular Center, 5-7-1 Fujishiro-dai, Suita, Osaka 565-8565, Japan
Shiro Kamakura, MD: Department of Perinatology and Gynecology, National Cerebral and Cardiovascular Center, 5-7-1 Fujishiro-dai, Suita, Osaka 565-8565, Japan

DOI: https://doi.org/10.1016/j.joa.2013.11.002
Journal volume & issue: Vol. 30, no. 3
pp. 201 – 203

Abstract

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Here, we present a rare case of fetal bradyarrhythmia following magnesium sulfate therapy for preterm labor. After we switched treatment from ritodrine hydrochloride to magnesium sulfate at 25 weeks' gestation, the fetal heart rate dropped from 150 bpm to 80–100 bpm. Fetal echocardiography and magnetocardiography indicated bigeminy and trigeminy of blocked premature atrial contractions. It is well known that magnesium sulfate decreases the baseline and variability of fetal heart rate. Studies have reported a substantial decrease of 2–15 bpm in the baseline fetal heart rate, and magnesium has various effects on fetal heart rate patterns with a lower baseline fetal heart rate within the normal range of 110–160 bpm. This is the first report of magnesium sulfate-induced fetal bradyarrhythmia by prolongation of the refractory period of the atrioventricular node in the case of blocked premature atrial contractions. Clinicians should consider fetal bradyarrhythmia when the baseline fetal heart rate drops to <100 bpm after magnesium sulfate administration.

Published in Journal of Arrhythmia

ISSN: 1880-4276 (Print); 1883-2148 (Online)
Publisher: Wiley
Country of publisher: Australia
LCC subjects: Medicine: Internal medicine: Specialties of internal medicine: Diseases of the circulatory (Cardiovascular) system
Website: https://onlinelibrary.wiley.com/journal/18832148

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