Fetal supraventricular tachycardia, treating the baby by targeting the mother

Abstract

Fetal supraventricular tachycardia (SVT) is the most common form of fetal tachycardia. If started early in pregnancy, it can cause non-immune fetal hydrops. Echocardiography is the preferred method for the diagnosis with simultaneous pulsed Doppler recording from the superior vena cava and ascending aorta. Transplacental therapy with digoxin is the most common way of treatment. We present a case of fetal SVT detected at 26 weeks of pregnancy. Digoxin therapy restored the rhythm initially, but later paroxysms of fetal SVT persisted necessitating the addition of second antiarrhythmic medication which was discussed with the parents. The couple chose to proceed for premature delivery at 32 weeks.

Figure 1

Fetal echocardiography still image of simultaneous mitral inflow and aortic outflow obtained via five-chamber view. The heart rate was 143/min. The positive signal is due to aortic outflow and the negative signals are due to mitral inflow. The mechanical PR interval was 95 m/s. Ao, aortic outflow; E, mitral E wave; A, mitral A wave.

Figure 2

Simultaneous pulse Doppler recording during sinus rhythm, from the right pulmonary artery (positive signal) and right pulmonary vein (negative signal). The atrial contraction is denoted by an indentation in the pulmonary vein signal. The mechanical PR interval in this recording was 92 m/s.

Figure 3

Simultaneous pulse Doppler recording from the superior vena cava (SVC) and ascending aorta. The positive signal is caused by SVC blood flow, while the negative signal is caused by aortic flow. The A wave reversal is seen as negative signal, moving away from the heart. Note that the AV interval is longer than the VA interval. Ao, aortic outflow; D, SVC D wave (diastole); S, SVC S wave (systole); A, SVC A wave reversal (atrial contraction).