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.