Fetal Cardiac Inflow Characteristics in Response to Fetal Anemia: Based on Fetal Hemoglobin Bart's Disease at Mid-Pregnancy

Abstract

Objectives: To identify the inflow (filling time fraction [FTF] and E/A ratio) characteristics of fetuses with anemia, and to evaluate the performance of the inflow markers in predicting the affected fetuses. Methods: Fetuses at risk of hemoglobin (Hb) Bart's disease at 17–22 weeks were prospectively recruited to undergo echocardiography before diagnostic cordocentesis. Cardiac Doppler images were digitally stored for off-line blinded measurements of FTF and E/A ratio. Results: A total of 428 fetuses at risk of Hb Bart's disease were analyzed, including 88 affected fetuses (20.6%). The mean gestational age at the time of diagnosis was 19.43 ± 1.5 weeks. The FTFs in both sides were significantly lower in the affected fetuses, whereas the E/A ratios of both sides were significantly higher in the affected group. According to the receiver operating characteristic curves, the performance of the FTF of the right side in predicting affected fetuses was slightly better than that of the left side (area under curve: 0.707 versus 0.680, P <.001). Likewise, the performance of the E/A ratio of the tricuspid valve was slightly better than that of the mitral valve. Also, FTF was superior to E/A ratio in predicting the affected fetuses. Conclusions: New insights leading to a better understanding of the fetal cardiac response to anemia are: 1) the FTFs in both sides were significantly decreased, suggesting some degree of diastolic ventricular dysfunction; 2) the E/A ratios of both sides were significantly increased, indicating volume load; and 3) The inflow parameters may be useful as a new predictor of fetal anemia, especially among pregnancies at risk.