Citation, DOI and article data
Fetal tachycardia is an abnormal increase in the fetal heart rate. It is variably defined as a heart rate above 160-180 beats per minute (bpm) and typically ranges between 170-220 bpm (higher rates can occur with tachyarrhythmias).
The estimated prevalence is ~0.4-1% of pregnancies 3,7.
In the majority of cases, the abnormal electrical impulses originate from the atria.
A fetal tachycardia can be associated with many maternal, as well as fetal conditions, which include:
- maternal hyperthyroidism
- maternal medications
- maternal tachycardia (e.g. systemic infection)
An M-mode Doppler study is best for assessment of heart rate. It is recommended that the sampling line intercepts both the atrial and ventricular walls, thereby allowing simultaneous assessment of both ventricular and atrial contractility.
Ultrasound may also show evidence of associated complications, such as signs of hydrops fetalis.
Treatment and prognosis
The long-term prognosis for most fetuses diagnosed with sinus tachycardia is generally good, with the abnormal rhythm resolving spontaneously during the first year of life in the majority of cases 5. Treatment options (if required) include transplacental administration of antiarrhythmic drugs.
History and etymology
It was first recognized by A S Hyman in 1930 2.
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- 2. Hyman AS. Irregularities of the fetal heart: a phonocardiographic study of the fetal heart sounds from the fifth to eighth months of pregnancy. Am J Obstet Gynecol. 1930;20:332–347.
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- 5. Lulić jurjević R, Podnar T, Vesel S. Diagnosis, clinical features, management, and post-natal follow-up of fetal tachycardias. Cardiol Young. 2009;19 (5): 486-93. doi:10.1017/S1047951109990497 - Pubmed citation
- 6. Brown DL. Sonographic assessment of fetal arrhythmias. AJR Am J Roentgenol. 1997;169 (4): 1029-33. AJR Am J Roentgenol (citation) - Pubmed citation
- 7. Entezami M, Albig M, Knoll U et-al. Ultrasound Diagnosis of Fetal Anomalies. Thieme. (2003) ISBN:1588902129. Read it at Google Books - Find it at Amazon