Fetal supraventricular tachycardia
Fetal supraventricular tachycardia (SVT) is considered the most common type of fetal tachyarrhythmia and can accounts for 60-90% of such cases.
It has a typical ventricular rate of ~230-280 beats per minute (bpm) 1 and is
often associated with an accessory AV conduction pathway. There is a 1 to 1 atrio-ventricular conduction. A supraventricular tachycardia is only rarely associated with intra or extra-cardiac anomalies (in contrast to other tachyarrhythmias).
- Wolfe-Parkinson-White syndrome: may be present in ~10% of cases
The diagnosis of supraventricular tachycardia can be established using M-mode echocardiography, which may demonstrate paroxysms of atrial tachycardia in the range of 230 - 280 beats per minute (BPM), often following an extra-systole. M-mode echocardiography uses a sampling line placed across atrial and ventricular walls and times electromechanical events in the fetal cardiac cycle. However it is often not possible to completely identify its precise electropathophysiologic mechanism by this method.
- development of hydrops fetalis
Treatment and prognosis
The management of the fetus with a normal anatomical survey and supraventricular tachycardia is dependent upon the gestational age at diagnosis, and the presence or absence of hydrops fetalis. Digoxin is often considered the drug of first choice. Compared with other arrhythmias, the overall perinatal mortality rate is considered low at ~5-10% (particularly if there are no complications such as development of hydrops fetalis).
- 1. Hornberger LK, Sahn DJ. Rhythm abnormalities of the fetus. Heart. 2007;93 (10): 1294-300. doi:10.1136/hrt.2005.069369 - Free text at pubmed - Pubmed citation
- 2 Mongiovì M, Pipitone S. Supraventricular tachycardia in fetus: how can we treat ? Curr. Pharm. Des. 2008;14 (8): 736-42. Curr. Pharm. Des. (link) - Pubmed citation
- 3. Simpson LL, Marx GR, D'alton ME. Supraventricular tachycardia in the fetus: conservative management in the absence of hemodynamic compromise. J Ultrasound Med. 1997;16 (7): 459-64. J Ultrasound Med (abstract) - Pubmed citation
- 4. 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