Table 7.3.

In utero management of tachycardias

Diagnosis	In utero management	GOR/LOE	Comments
Intermittent tachycardia
SVT or AF	Observation	I/B	Frequent fetal HR auscultation
VT ≥ 200 bpm	Antiarrhythmic medication	IIa/C
Sustained tachycardia
SVT or AF with hydrops or ventricular dysfunction	First or second line (transplacental) drugs:		See Table 7.4, for dosing ranges and monitoring recommendations
	Digoxin	I/B
	Sotalol	I/B
	Combination of drugs (transplacental)	IIb/B	Combination treatments are used for severe, drug-refractory cases. Consider preterm delivery if near term
	Third line (transplacental):
	Amiodarone	I/B
	Contraindicated: verapamil	III/A
	Contraindicated: procainamide	III/B
	Direct fetal treatment:
	IM digoxin	IIa/B
	Intracordal digoxin	IIb/B
	Contraindicated: Intracordal adenosine	III/B
SVT ≥ 200 bpm, without hydrops or ventricular dysfunction (usually SVT has HR ≥ 220 bpm; consider other causes if HR < 220 bpm).	First or second line:
	Digoxin	I/B	See Table 7.4, for doses and monitoring recommendations
	Sotalol	I/B	Frequent monitoring of fetal well-being and maternal/fetal drug toxicity. Consider preterm delivery if near term.
	Third line:
	Amiodarone	IIb/B
	Contraindicated: verapamil	IIb/A
	Contraindicated: procainamide	III/B
	Observation	I/B
SVT < 200 bpm, without hydrops or ventricular dysfunction	Sotalol	I/B	Digoxin increases AVB and decreases ventricular response. Consider preterm delivery if near term
AF	Digoxin	I/B
	Amiodarone	IIb/B
	Contraindicated: procainamide	III/B
VT ± hydrops		I/C
First line treatment	Magnesium IV Lidocaine IV Propranolol (oral)	I/C	FMCG (if available) to measure QTc interval. Start with magnesium IV, then lidocaine, load + maintenance. Note: maternal intravenous magnesium should not be used for > 48 h. Consider preterm delivery if near term.
Second line treatment	Mexiletina (oral) Sotalol	I/C

AF: atrial flutter; GOR: grade of recommendation; IV: intravenous; HR: heart rate; IM: intramuscular; FMCG: fetal magnetocardiography; LOE: level of evidence; SVT: supraventricular tachycardia; VT: ventricular tachycardia.

Source: adapted from Donofrio MT et al.¹⁷