Dynamic Slow-Motion Display in the Diagnosis of Functional Pulmonary Atresia in Fetal Ebstein Anomaly.

Introduction

Fetal tricuspid valve disease with severe tricuspid valve insufficiency, including both Ebstein anomaly and tricuspid valve dysplasia, is frequently associated with cardiovascular compromise in utero. Therefore, the overall prognosis of affected fetuses is extremely poor. Above all, the presence or absence of anterograde flow to the pulmonary artery is an important factor determining a prognosis of Ebstein anomaly. However, it is difficult to diagnose the presence or absence of anterograde flow to the pulmonary artery as functional pulmonary atresia.

Case Presentation

A 23-year-old woman was referred to our hospital at 19 weeks' gestation because of cardiomegaly. Fetal echocardiography demonstrated cardiomegaly (cardiothoracic area ratio 45%) and severe tricuspid valve insufficiency in the four-chamber view. We diagnosed Ebstein anomaly. The pulmonary artery flow was observed in an anterograde direction.

At 32 weeks' gestation, fetal echocardiography showed severe cardiomegaly (cardiothoracic area ratio 55%), and pulmonary artery flow was observed in a retrograde direction. The blood flow direction of the ductus arteriosus spread toward the pulmonary artery. These findings suggested that the pulmonary valve was closed. Furthermore, investigation using dynamic slow-motion display visualized the movement of the pulmonary valve and a small amount of regurgitation flow at the pulmonary valve in end-systole more clearly (Figure 1, Video 1). Finally, we diagnosed functional pulmonary atresia. Diagnosis after birth was similar.

Figure 1

Dynamic slow-motion display. (A) A monochrome image of dynamic slow-motion display showing the right ventricular outflow tract. The motion of the pulmonary valve can be clearly visualized. (B) A color image of dynamic slow-motion display. A slight amount of pulmonary valve regurgitation is clearly seen at the end-systolic phase.

Discussion

It is necessary to find a small amount of pulmonary regurgitation to diagnose functional pulmonary valve atresia. However, to find a small amount of pulmonary regurgitation is difficult because the fetal heart rate is rapid. Therefore, fetal echocardiography must use a high frame rate. The color Doppler method is necessary to find small amount of pulmonary valve regurgitation. However, the dilemma is that the frame rate decreases if color Doppler is used.

With dynamic slow-motion display, slow reproduction is possible without decreasing frame rate. Therefore, dynamic slow-motion display is suitable for observation of the valve function of fetuses (Videos 1 and 2). In the present case we were able to visualize a small amount of pulmonary regurgitation clearly using dynamic slow-motion display.

Conclusion

Dynamic slow-motion display is useful for the diagnosis of fetal valve form and function.