Table 2 The treatment of choices for fetal tachyarrhythmias [43, 44]

Indication

Paroxymal SVT, short VA SVT, nonhydropic fetuses

SVT with NIHF, refractory SVT, SVT with heart failure unresponsive to soltalol and digoxin

AF, SVT

SVT resistant to digoxin, AF

Dose

Loading: 1.5–2 mg over 24–48 h; Maintenance: 0.375–1 mg/day

Loading: 200–300 mg divided b.i.d., or t.i.d.;

Maintenance: 450 mg/day if no response

Loading: 160–320 mg divided b.i.d.;

Maintenance: increased to 480 mg/day

Loading: 1600–2400 mg/day 2–4 times per day;

Maintenance: 200–400 mg/day b.i.d.

Route

p.o., or i.v.

p.o.

p.o.

p.o., or i.v.

Fetal/maternal serum level (%)

40–90

10–50

Advantage

Safe and effective

Not accumulate in fetus, not cause intrauterine growth retardation

Little or no negative inotropic effect

Adverse effect

Digoxin monotherapy showed a lower effective rate than combined;

Hydropic fetuses refractory to digoxin

Intrauterine death

Negative inotropic effect, intrauterine death

Arrhythmogenic effect, fetal thyroid functional impairement, maternal thrombocytopenia and skin rash