Treatment of Fetal and Neonatal Arrhythmias

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Fetal and neonatal arrhythmias are diverse in type and severity. They include both tachycardias and bradycardias.1 The innate physiological properties of the fetal and neonatal myocardiums make them more vulnerable to these high or low ventricular rates. Irregularities of fetal and neonatal cardiac rhythm commonly occur, and rarely have serious consequences; however, it is important to realize that sustained tachycardias and bradycardias can lead to heart failure and hydrops fetalis.2,3


Fetal Arrhythmias
Fetal arrhythmias are noted in only 1% of all pregnancies and can be categorized by rate and regularity. Almost all arrhythmias fall into one of three categories: irregular, tachycardic, or bradycardic.4 Normal fetal heart rates range from 120 to 160bpm at 30 weeks of gestation, and from 110 to 150bpm at term.5,6 Heart rates below 100bpm are classified as bradycardia, and rates greater than 180bpm as tachycardia.1,7

Fetal arrhythmias are often first noted on auscultation during routine maternal pre-natal examinations once heart tones are appreciated, at around 10th weeks. Generally, the mother is asymptomatic and does not notice any decreased fetal activity.1,4 If a fetal tachycardia is heard, the referring practitioner should attempt to determine its rate and characteristics. Gradual onset and cessation are associated with normal fetal accelerations, especially with a rate below 200bpm. Abrupt changes, especially if the rate is over 200bpm, are more often associated with pathological tachycardias.8 Transient slowing of the fetal heart rate with immediate return to normal rates is common mid-trimester when patients lie supine, caused by normal variable-type fetal heart rate decelerations, and does not need further cardiac evaluation. This isolated physiological slowing of the heart must be differentiated from persistent bradycardia, which requires expedited evaluation.8,9

Approximately 50% of fetuses referred for evaluation of fetal arrhythmias are in normal sinus rhythm, with the vast majority having isolated supraventricular systoles. Fewer than 10% of fetuses are found to have sustained tachyarrhythmias or bradyarrhythmias.2

Once an arrhythmia is detected by auscultation, an additional evaluation is indicated. Currently, external acquisition of fetal electrocardiography is not available.8 Other non-invasive approaches include 2D fetal echocardiography, to exclude structural cardiac defects, and M-mode ultrasonography, which depicts cardiac motion as a function of time. A cursor placed through both the fetal atrium and ventricle allows the timing of atrial and ventricular contractions to be determined and premature beats to be identified.8,10,11 Similarly, pulsed Doppler can be used to identify fetal rhythms by assessing intracardiac flow patterns.10,12 Fetal magnetocardiography uses the magnetic field generated by electrical activity of the fetal heart for a more precise delineation of fetal rhythms.13,14

Fetal Tachyarrhythmias
Fetal tachycardias may have several causes. It is important to exclude fetal distress (with loss of beat-to-beat variability) and chorioamnionitis (with maternal fever), which may cause fetal heart rates of up to 200bpm.8 The three most common fetal tachyarrhythmias, aside from premature atrial contractions (PACs), are supraventricular (re-entrant) tachycardia (SVT), atrial flutter (AF), and ventricular tachycardia (VT). PACs are fetal extra-systoles, and are associated with good outcomes.8 In 0.4% of cases, PACs may progress to fetal tachycardia. Therefore, it is recommended that these patients be monitored weekly to exclude the development of tachyarrhythmias.8,15

AF accounts for approximately 21% of fetal tachycardia, and may be associated with structural abnormalities. Fetal hydrops is associated with 7% of AF cases.16,17 AF is defined as an atrial rate ranging from 250 to 500bpm with either fixed or variable atrioventricular (AV) block,18and diagnosis can be confirmed by fetal echocardiography, which documents the atrium beating at a faster rate than the ventricle.1 Medical management in cases without hydrops may consist simply of digoxin therapy, whereas in other cases adding a second agent such as flecainide, procainamide, or amiodarone may be needed.8 Drug therapy is successful in 82% of patients. Hydropic fetuses may require more medication and a longer treatment period to control the condition.19


  1. Tanel RE, Rhodes LA, Fetal and neonatal arrhythmias, Clin Perinatol, 2001;28(1):187├óÔé¼ÔÇ£207.
  2. Kleinman CS, Neghme RA, Cardiac arrhythmias in the human fetus, Pediatr Cardiol, 2004;25(3):234├óÔé¼ÔÇ£51.
  3. Wren C, Cardiac arrhythmias in the fetus and newborn, Semin Fetal Neonatal Med, 2006;11(3):182├óÔé¼ÔÇ£90.
  4. Cullen T, Evaluation of fetal arrhythmias, Am Fam Physician, 1992;46(6):1745├óÔé¼ÔÇ£9.
  5. Rooth G, Huch A, Huch R, Guidelines for the use of fetal monitoring, Int J Gynecol Obstet, 1987;25:159.
  6. Nijhuis IJM, ten Hof J, Mulder EJH, et al., Antenatal fetal heart rate monitoring; normograms and minimal duration of recordings, Prenat Neonat Med, 1998;3:314├óÔé¼ÔÇ£22.
  7. Kleinman CS, Neghme R, Copel JA, et al., Fetal cardiac arrhythmias: diagnosis and therapy. In: Creasy RK, Resnik R (eds), Maternal├óÔé¼ÔÇ£fetal Medicine, Philadelphia, PA: Saunders, 1998;301├óÔé¼ÔÇ£18.
  8. Copel JA, Friedman AH, Kleinman CS, Management of fetal cardiac arrhythmias, Obstet Gynecol Clin North Am, 1997;24(1): 201├óÔé¼ÔÇ£11.
  9. Mendoza GJ, Almeida O, Steinfeld L, Intermittent fetal bradycardia induced by midpregnancy fetal ultrasonographic study, Am J Obstet Gynecol, 1989;160:1038├óÔé¼ÔÇ£40.
  10. Cameron A, Nicholson S, Nimrod C, et al., Evaluation of fetal cardiac dysrhythmias with two-dimensional, M-mode, and pulsed Doppler ultrasonography, Am J Obstet Gynecol, 1988;158:286├óÔé¼ÔÇ£90.
  11. Silverman NH, Enderlein MA, Stanger P, et al., Recognition of fetal arrhythmias by echocardiography, J Clin Ultrasound, 1985;13(4): 255├óÔé¼ÔÇ£63.
  12. Kleinman CS, Copel JA, Hobbins JC, Combined echocardiographic and Doppler assessment of fetal congenital atrioventricular block, Br J Obstet Gynaecol, 1987;94(10):967├óÔé¼ÔÇ£74.
  13. Quartero HW, Stinstra JG, Golbach EG, et al., Clinical implications of fetal magnetocardiography, Ultrasound Obstet Gynecol, 2002;20(2):142├óÔé¼ÔÇ£53.
  14. Grimm B, Haueisen J, Huotilainen M, et al., Recommended standards for fetal magnetocardiography, Pacing Clin Electrophysiol, 2003;26(11):2121├óÔé¼ÔÇ£6.
  15. Strasburger JF, Fetal arrhythmias, Prog Pediatr Cardiol, 2000;11(1): 1├óÔé¼ÔÇ£17.
  16. Kleinman CS, Copel JA,Weinstein EM, et al., Treatment of fetal supraventricular tachyarrhythmias, J Clin Ultrasound, 1985;13(4): 265├óÔé¼ÔÇ£73.
  17. Jaeggi E, Fouron JC, Drblik SP, Fetal atrial flutter: diagnosis, clinical features, treatment, and outcome, J Pediatr, 1998;132(2):335├óÔé¼ÔÇ£9.
  18. Oudijk MA, Visser GH, Meijboom EJ, Fetal tachyarrhythmia├óÔé¼ÔÇØpart I: diagnosis, Indian Pacing Electrophysiol J, 2004;4(3):104├óÔé¼ÔÇ£13.
  19. Van Engelen AD,Weijtens O, Brenner JI, et al., Management, outcome, and follow-up of fetal tachycardia, J Am Coll Cardiol, 1994;24(5):1371├óÔé¼ÔÇ£5.
  20. Simpson JM, Sharland GK, Fetal tachycardias: management and outcome of 127 consecutive cases, Heart, 1998;79(6):576├óÔé¼ÔÇ£81.
  21. Hallak M, Neerhof MG, Perry R, et al., Fetal supraventricular tachycardia and hydrops fetalis: combined intensive, direct, and transplacental therapy, Obstet Gynecol, 1991;78:523├óÔé¼ÔÇ£5.
  22. Frohn-Mulder IM, Stewart PA, Witsenburg M, et al., The efficacy of flecainide versus digoxin in the management of fetal supraventricular tachycardia, Prenat Diagn, 1995;15(13): 1297├óÔé¼ÔÇ£1302.
  23. Taylor PV, Scott JS, Gerlis LM, et al., Maternal antibodies against fetal cardiac antigens in congenital complete heart block, N Engl J Med, 1986;315(11):667├óÔé¼ÔÇ£72.
  24. Copel JA, Buyon JP, Kleinman CS, Successful in utero therapy of fetal heart block, Am J Obstet Gynecol, 1995;173(5):1384├óÔé¼ÔÇ£90.
  25. Silverman ED, Congenital heart block and neonatal lupus erythematosus: Prevention is the goal, J Rheumatol, 1993;20:1101├óÔé¼ÔÇ£4.
  26. Groves AMM, Allan LD, Rosenthal E, Therapeutic trial of sympathomimetics in three cases of complete heart block in the fetus, Circulation, 1995;92:3394├óÔé¼ÔÇ£6.
  27. Dubin AM, Arrhythmias in the newborn, Neoreviews, 2000;1: 146├óÔé¼ÔÇ£51.
  28. Kothari DS, Skinner JR, Neonatal tachycardias: an update, Arch Dis Child Fetal Neonatal Ed, 2006;91(2):F136├óÔé¼ÔÇ£44.
  29. Salerno JC, Kertesz NJ, Friedman RA, Fenrich AL Jr, Clinical course of atrial ectopic tachycardia is age-dependent: results and treatment in children <3 or ├óÔÇ░─ä3 years of age, J Am Coll Cardiol, 2004;43(3):438├óÔé¼ÔÇ£44.
  30. Bauersfeld U, Gow RM, Hamilton RM, Izukawa T, Treatment of atrial ectopic tachycardia in infants <6 months old, Am Heart J, 1995;129(6):1145├óÔé¼ÔÇ£8.
  31. Epstein ML, Kiel EA, Victorica BE, Cardiac decompensation following verapamil therapy in infants with supraventricular tachycardia, Pediatrics, 1985;75(4):737├óÔé¼ÔÇ£40.