EP09.57: Intracardiac intermediate diastolic velocity in response to fetal anemia: using hemoglobin Bart's disease as a study model

To compare the intermediate diastolic velocity (IDV) measurements, as well as E/IDV and A/IDV ratios of cardiac Doppler between the fetuses affected and unaffected by Hb Bart's disease among pregnancies at risk. The prospective database of pregnancies at risk of having a fetus affected by Hb Bart's disease at 17-22 weeks were accessed to retrieve the consecutive records, including baseline data, clinical data, and echocardiographic findings. The digital spectral Doppler images were also retrieved for off-line blinded measurements of IDV, E/IDV and A/IDV ratios. A total of 418 fetuses were evaluated for cardiac function, including 84 fetuses with Hb Bart's disease and 334 unaffected fetuses. In the right ventricle, the IDV was significantly lower in the affected group (24.51##+5.76 vs 26.66##+6.88, p value = 0.010), whereas the IDV in the left ventricle was significantly higher in the affected group (22.36##+5.79 vs 20.54##+5.54, p value = 0.008). E/IDV and A/IDV ratios were significantly lower in the left ventricle, whereas they tended to be higher in the right ventricle, though not significantly, in the affected group. The other parameters of cardiac function in the affected fetuses showed significant changes, such as increased cardiac output and increased myocardial performance index (MPI) on the right side, which were significantly greater than those on the left side. The findings indicate that cardiac workload secondary to fetal anemia was more pronounced on the right side. In fetal anemia, at the initial phase, the heart seems to improve ventricular diastolic function, more obviously seen in the left ventricle, probably caused by a decrease in afterload induced by anemic hypoxia. Nevertheless, with progressive changes of volume load and pressure load in response to longstanding anemic hypoxia, the overworked heart causes a gradually progressive deterioration of ventricular diastolic function, which is more predominant in the right side.