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Postnatal management of fetal arrhythmias

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Objectives

To promote early contact with cardiology and ensure appropriate monitoring for babies receiving a prenatal diagnosis of an arrhythmia

Scope

This guideline is for neonatologists and paediatric cardiology teams, caring for babies with a prenatal diagnosis of a fetal arrhythmia. 

Introduction / Background

Fetal arrhythmias are uncommon and the incidence of structural cardiac abnormalities in fetuses with irregular heart rhythms is low (<2%). Ectopic beats are estimated to be present in around 1% of unselected pregnancies and in the majority of cases will resolve before delivery. 

Fetal tachycardia can result in significant morbidity and mortality if left untreated in utero. The ideal management is to treat the tachycardia prior to delivery so that the fetus is delivered in a non-hydropic state, at term, without evidence of tachycardia. Prenatal therapy is guided by the fetal cardiology and fetal medicine team jointly and in our institution 1st line maternal therapy is flecainide, with the addition of digoxin in resistant tachycardias as a second line therapy. Therapy is carefully considered, implemented and monitored due to the potential adverse effects to the mother and fetus. 

Some patients may have been recruited as part of the international FAST trial (Fetal atrial flutter and supraventricular tachycardia trial). This study aims to compare the impact of different prenatal treatment strategies from the time of diagnosis of fetal supraventricular tachyarrythmia (SVT) to 30 days after birth. Maternal therapy will include a combination of digoxin, flecainide or sotolol, determined by trial randomisation or families may wish to be placed upon the registry, following normal institutional management. 

1. Fetal Irregular Heart Rhythm

a) If extrasystoles persist after birth

  • Remain on PNW for 48 hours before discharge home
  • 12 lead ECG
    • Mon-Fri 9-5pm arrange with cardiology department (84437), out of hours/weekend to be undertaken by the neonatal team
  • Auscultate HR for 1 minute
    • If ectopic every 10 beats - discuss with cardiology oncall (84440) whether a 24 hour ECG is required
    • If less frequent, no further investigations required but the baby should remain on PNW until 48 hrs old
  • Discuss 24 hour ECG with cardiology consultant and arrange f/u as required
  • If ventricular extra-systoles (VEs) on ECG, discuss with cardiology consultant or oncall cardiology registrar (84440)

b) If extra-systoles have resolved prior to birth

  • No postnatal follow-up or investigation is indicated.
2. Fetal Tachycardia

a) Failure to cardiovert medically during fetal life

  • Admit to NICU
  • Inform on call cardiology consultant or cardiology registrar (84440) immediately
  • Continuous ECG monitoring
  • Baseline echocardiogram and 12 lead ECG
  • Medical therapy/cardioversion as per on call cardiologist advice


b) Successful medical cardioversion during fetal life

  • Admit to NICU for 72 hours
  • Request cardiology consult (84440) within normal working hours if in sinus rhythm and cardiovascularly stable
  • Baseline echocardiogram and 12 lead ECG
  • Ensure parents are taught and competent at checking the heart rate by measuring the pulse/listening with stethoscope or ear.
  • Families will be provided with an information leaflet before discharge home, detailing monitoring and measuring heart rate – cardiac liaison nurses will provide leaflet.
  • Parents should assess the heart rate at least twice daily when baby settled.
  • On discharge, parental advice to seek urgent medical attention if evidence of poor feeding, or tachycardia i.e. >180bpm when baby settled.
  • Provide contact details for the cardiac liaison team for non urgent support between outpatient clinics: Cardiacliaison.nursespaeds@ggc.scot.nhs.uk (0141 452 4925)
  • Arrange Cardiology OPC for 2 weeks post discharge.

  • If tachycardia recurs before discharge, therapy and f/u as per on call cardiologist advice
References
  1. FAST Trial – Fetal Atrial Flutter and Supraventricular Tachycardia Trial. Multicentre, international registry and RCT. Jeaggi et al, Toronto Sick Kids Hospital, Toronto, Canada.
  2. Jaeggi E, Ohman A. Fetal and Neonatal Arrhythmias. Clin Perinatol. 2016 Mar;43(1):99-112.
  3. Simpson J, Silverman N. Diagnosis of cardiac arrhythmias during fetal life. In: Gembruch U, editor. Fetal Cardiology. London: Martin Dunitz; 2003. p. 333-344.
  4. Vergani P, Mariani E, Ciriello E, Locatelli A, Strobelt N, Galli M, Ghidini A. Fetal arrhythmias: natural history and management. Ultrasound med Bio 2005 Jan;31(1):1-6
  5. Van Engelen AD, Weijtens O, Brenner JI, Kleinman CS, Copel JA, Stoutenbeek P, et al. Management outcome and follow-up of fetal tachycardia. J Am Coll Cardiol 1994;24(5):1371-5.
  6. Simpson JM, Sharland GK. Fetal tachycardias: management and outcome of 127 consecutive cases. Heart 1998;79(6):576-81.
  7. Frohn-Mulder IM, Stewart PA, Witsenburg M, Den Hollander NS, Wladimiroff JW, Hess J. The efficacy of flecainide versus digoxin in the management of fetal supraventricular tachycardia. Prenat Diagn 1995; 15(13):1297-302.
  8. Echt DS, Liebson PR, Mitchell LB, Peters RW, Obias-Manno D, Barker AH, et al. Mortality and morbidity in patients receiving encainide, flecainide, or placebo. The Cardiac Arrhythmia Suppression Trial. N Engl J Med 1991;324(12):781-8.
  9. Fouron JC. Fetal arrhythmias: the Saint-Justine hospital experience. Prenat Diagn 2004;24(13):1068-80.
Editorial Information

Last reviewed: 01 May 2020

Next review: 31 May 2022

Author(s): Dr Lindsey Hunter; Dr Karen McLeod; Lorraine Mulholland; Kathleen O’Reilly

Version: 1

Approved By: Paediatric Cardiology & Neonatology

Reviewer Name(s): A Powls; M Worrall; G Bell