Purpose or Case Report: A 22-year-old G2P1 female presented to our institution at 22 weeks for fetal cardiology evaluation of hypoplastic left heart syndrome (HLHS) with mitral stenosis and aortic atresia. Fetal echocardiogram confirmed the diagnosis and suggested a severely restricted atrial septum with a pulmonary venous forward/reverse time-velocity integral ratio (VTI) of 2.7.
At 29 weeks' gestation, she underwent a fetal CMR to evaluate for pulmonary lymphangiectasia and interatrial septum.
Fetal cardiac gating was obtained with an MR-compatible Doppler ultrasound device (Smartsync, Northh Medical) and imaging was performed at 3T.
In addition to the findings of HLHS, findings at fetal CMR included an intact/severely restrictive atrial septum with markedly dilated pulmonary veins. Additionally, there was an anomalous pulmonary vein connecting the right sided pulmonary veins to both the azygos vein and the SVC. 4D flow MRI quantified the distribution of blood flow, demonstrated a similar pulmonary venous forward/reverse flow ratio of 2.4 and visualized the anomalous vessel decompressing the pulmonary venous system into the systemic venous system. There was a segmental pattern of pulmonary lymphangiectasia, present in the right middle lobe and lingula.
Same day fetal echocardiography also confirmed the anatomical findings. The patient was determined not to be a candidate for fetal intervention and following counselling, the family elected for comfort care at delivery. After delivery, the baby did not demonstrate clinical signs of a restrictive atrial septum, despite an atrial septal gradient of 11mmHg by echocardiography, and following re-evaluation, underwent a staged single ventricle palliation. At surgery for stage 1 (Norwood-Sano), the atrial septum was found to be almost intact. The infant continues to do well and currently is status post stage 2 with a superior cavopulmonary anastomosis.
This case demonstrates the use of fetal CMR with an MR compatible doppler ultrasound device in the fetal evaluation of HLHS with a suspected restrictive atrial septum. In this case, fetal CMR with 4D flow was able to calculate a pulmonary venous forward/reverse flow ratio similar to echocardiography and demonstrated the anomalous pulmonary venous drainage pathway, which likely accounted for the absence of the expected severe manifestations of an intact atrial septum in addition to the relatively mild manifestations of pulmonary lymphangiectasia.
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