Case Report
A 24-year-old primigravida, booked low risk in a different hospital. Her booking blood results ultrasound scan were normal with Haemoglobin level of 144 g/L, and she had a normal anomaly scan at 20 weeks gestation. She had regular uneventful antenatal midwife-led care and had no significant past medical history of note. At each clinic visit, the fetal heart rate (FHR) was normal in keeping with gestational age.
At 37 weeks gestation she attended her routine antenatal care, also with first episode of reduced fetal movement. There was difficulty in detecting the FHR by both the hand-held fetal Doppler and cardiotocographic (CTG) machine as the heartbeat was too fast. A quick bedside ultrasound scan showed FHR of 220 beats per minute (bpm). The maternal pulse was 100bpm with blood pressure of 128/76 mmHg. She was quickly transferred by ambulance to the Obstetric Unit of the nearest general hospital. A quick transabdominal ultrasound scan done by the Obstetric team showed live active singleton gestation with ventricular FHR of 260bpm with an impression of fetal SVT made. There was a discussion to go for emergency caesarean section however this was forestalled by specialist advice from the paediatric cardiologist in a tertiary hospital who advised for the patient to be transferred by ambulance to the University teaching hospital to provide adequate neonatal care after delivery.
On arrival at the tertiary hospital 2 hours later, obstetric ultrasonography showed estimated fetal weight compatible with her gestation, with normal liquor volume and normal anterior placentation. Fetal cardiac ultrasound done by the paediatric cardiologist revealed an atrial heart rate of 480bpm, and ventricular rate of 240bpm using the M-mode function. There was a mild tricuspid valve regurgitation, but no obvious cardiac structural anomaly or hydrops noted. A clinical impression of fetal AF at 480bpm with 2:1 nodal AV block was made. Options of management were discussed with the patient including medical antenatal treatment or abdominal delivery with neonatal management. Since the pregnancy was term, a joint agreement with the obstetric team was for urgent abdominal delivery and postnatal treatment to which the patient consented. She had an emergency caesarean section under regional block. The Outcome was a live female neonate who weighed 3530 grams at birth with favourable Apgar score although with poor colour.
The baby required some continuous positive airway pressure (CPAP) for support for a few minutes as the oxygen saturation was at 70% and was transferred immediately to the neonatal intensive care unit (NICU). ECG done showed ventricular hear beat of 235bpm (Figure 1), with persistent AF. A single synchronised direct-current cardioversion of 4 joules following ketamine sedation reverted the arrhythmia to sinus rhythm at 175 bpm. Loading dose of digoxin was started (15 mcg/kg) followed later by maintenance dose of 10mcg twice daily with serum digoxin level monitored. A neonatal echocardiography done on the day of delivery showed a patent foramen ovale (PFO), and mild tricuspid regurgitation with otherwise normal ventricular function.
The baby’s mother had a good post-operative recovery and was well debriefed with follow up plan made. There was no neonatal recurrence of AF while on admission, and on day 4 neonatal life, the baby was discharged back to the NICU of the general hospital where she was monitored for 3 days. She was then discharged home on same dose of digoxin for prophylaxis and the last serum digoxin level before discharge was normal at 1.5ug/L. Follow up echocardiogram done 8 weeks after discharged showed similar findings as before with normal ventricular function. The baby is to be followed up every few months with an echocardiogram and review, and there has been no concern so far. Her development has been normal up to the point of writing this article at the age of 4 months.