The Prenatal Diagnosis and Perinatal Management of Congenital Long QT Syndrome: A Comprehensive Literature Review and Recent Updates

Figures

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  Figure 1. Pulsed-wave Doppler evaluation of a 29-week fetal patient with 2:1 AV block. From left to right: The evaluation of mitral valve inflow–aortic valve outflow Doppler with atrial rate (A) and ventricular rate (B) measured and superior vena cava–aorta Doppler with atrial rate (C) and ventricular rate (D) measured. Red A = atrial beat; red V = ventricular beat.

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  Figure 2. M-mode evaluation of two fetal patients with confirmed LQTS. (A) M-mode cursor through atria and ventricular walls demonstrating 2:1 AV block in a 29-week gestational age fetus. (B) M-mode of short episode of ventricular tachycardia with ventricular rate > 200 bpm in a 32-week gestational age fetus. Red A = atrial beat; red V = ventricular beat.

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  Figure 3. The fMCG evaluation of a 36-week gestational age fetus with familial LQT 2: (A) Signal-averaged fMCG showing 3 QRS complexes. Note that the T waves are of different morphology and polarity as well as very prolonged (627 ms QTc). (B) A rhythm strip showing A:B:A:B-type T wave alternans during 1:1 AV conduction. Maternal complexes can also be seen in the lower panel. (C) Five-second rhythm tracing, showing the onset of organized TdP ventricular tachycardia, which at the time exceeded 300 beats per min.

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  Figure 4. The fMCG evaluation of a 26-week gestational age fetus with negative family history, 2:1 AV block, and hydrops fetalis: (A) Fetal heart rate trend graph and fetal movement (actogram) over 5 min, showing multiple brief episodes of fetal rhythm a little faster than sinus, yet the pattern is due to TdP. This fetus had spontaneous fetal demise at 28 weeks gestational age and later was confirmed with genetics to have de novo LQT3, SCN5A mutation. (B) 20 s and 5 s rhythm tracings showing disorganized TdP ventricular tachycardia self-terminating to 2:1 AV block, with severe QTc prolongation. (C) Signal-averaged fMCG showing central QRS with severe QTc prolongation 854 ms. This fetus did not show prominent T wave alternans.

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  Figure 5. Flow diagram showing multidisciplinary approach to the prenatal management of suspected LQTS from diagnosis through delivery.