PMC5420015_01
Case 1. A: At 29 weeks, a fetal echocardiogram showed ventricular tachycardia (VT) with a ventricular rate of 220 beats per minute (bpm), compared with an atrial rate of 130 bpm. B: Fetal magnetocardiography (fMCG) revealed polymorphic VT. C: fMCG showed a prolonged QT interval (591 ms) during sinus rhythm.
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One week later, a follow-up fetal echocardiogram showed a ventricular rate of 220 bpm (atrial rate was 130 bpm) (Figure 1A). An fMCG was then performed which revealed nonsustained VT alternating with sinus rhythm (rate 130 bpm) (Figure 1B). The QTc was 591 ms (Figure 1C).
Case 1. A: The infant's heart rate at the time of birth was 56 beats per minute (bpm), and he had a 2:1 atrioventricular block. B: On the 14th day of life, the electrocardiogram showed a sinus rhythm with a left bundle branch block pattern. C: At the age of 5 months, an implantable cardioverter-defibrillator was implanted.
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The heart rate at birth was 56 bpm owing to functional second-degree AVB with 2:1 conduction (Figure 2A). On the 14th day of life, the infant's electrocardiography showed sinus rhythm with a left bundle branch block pattern (Figure 2B). The shock lead was implanted subcutaneously through the left thoracodorsal region, and the generator was placed under the right abdominal rectus muscle (Figure 2C).
PMC5420015_02
Case 2. A: At 24 weeks' gestation, the initial fetal echocardiography showed fetal ventricular tachycardia with a ventricular rate of 187 beats per minute (bpm) and an atrial rate of 123 bpm. B: Fetal magnetocardiography (fMCG) revealed sustained ventricular tachycardia with a V rate of 220 bpm. C: fMCG showed a prolonged QT interval (511 ms) during transient sinus rhythm. D: At this time, the fetus also developed ascites, skin edema, and pericardial effusion as symptoms of severe hydrops.
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The fetal echocardiogram revealed a peristent tachycardia with atrioventricular dissociation (Figure 3A). The fMCG confirmed the clinical diagnosis of VT with a rate of 220 bpm (Figure 3B) with a prolonged (511 ms) QTc during brief (<20% of the recording time) episodes of sinus rhythm (rate 110-120 bpm) (Figure 3C). However, despite maternal serum magnesium levels of 1.28 mmol/L (normal range 0.65-1.05 mmol/L), the VT persisted and the fetus became hydropic (Figure 3D).