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Intracardiac Intermediate Diastolic Velocity in Response to Fetal Anemia: Using Hemoglobin Bart's Disease as a Study
Rapeepat Auekitrungrueng1, Suchaya Luewan1,2, Theera Tongsong1,2
1Department of Obstetrics and Gynecology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.
Insights
Fetal Hb Bart's disease impacts diastolic function, initially enhancing it in the left ventricle but later causing deterioration, particularly in the right ventricle. This study compared diastolic velocity measurements in affected and unaffected fetuses.
Area of Science:
- Fetal Medicine
- Cardiology
- Hematology
Background:
- Hemoglobin Bart's disease is a severe form of alpha-thalassemia.
- Fetal anemia significantly impacts cardiovascular function.
- Understanding diastolic function changes is crucial for managing affected fetuses.
Purpose of the Study:
- To compare intermediate diastolic velocity (IDV) and E/IDV, A/IDV ratios in fetuses with and without Hb Bart's disease.
- To assess the impact of Hb Bart's disease on fetal cardiac function.
- To investigate early diastolic function changes in fetal anemia.
Main Methods:
- Retrospective analysis of 418 fetuses at risk for Hb Bart's disease (17-22 weeks gestation).
- Off-line, blinded assessment of IDV, E/IDV, and A/IDV ratios.
- Evaluation of cardiac function parameters including cardiac output and myocardial performance index (MPI).
Main Results:
- Significantly lower right ventricular IDV and higher left ventricular IDV in affected fetuses.
- Lower left ventricular E/IDV and A/IDV ratios in fetuses with Hb Bart's disease.
- Affected fetuses showed greater right-sided cardiac output and MPI compared to the left.
Conclusions:
- Early fetal anemia may lead to enhanced ventricular diastolic function, especially in the left ventricle.
- Progressive disease and chronic anemic hypoxia overwhelm compensatory mechanisms.
- Diastolic function deteriorates over time, predominantly affecting the right ventricle.
Objective:
To compare intermediate diastolic velocity (IDV) measurements, as well as E/IDV and A/IDV ratios, between fetuses affected and unaffected by Hb Bart's disease.
Methods:
Fetuses at risk of Hb Bart's disease between 17 and 22 weeks of gestation were off-line and blindly assessed for IDV, E/IDV, and A/IDV ratios, along with parameters of cardiac function.
Results:
A total of 418 fetuses were included, comprising 84 affected and 334 unaffected cases. The IDV in the right ventricle was significantly lower in the affected group (24.5 ± 5.76 vs. 26.66 ± 6.88; p = 0.010), while the IDV in the left ventricle was significantly higher (22.36 ± 5.79 vs. 20.54 ± 5.54; p = 0.008). The E/IDV and A/IDV ratios in the left ventricle were significantly lower in the affected group. Among the affected fetuses, right-sided cardiac output and myocardial performance index (MPI) were significantly greater than those on the left side.
Conclusion:
In the early stages of fetal anemia, the heart appears to enhance ventricular diastolic function, more prominently in the left ventricle. However, as the condition progresses, with increasing volume and pressure load due to chronic anemic hypoxia, the compensatory mechanisms are eventually overwhelmed, leading to a gradual deterioration of diastolic function, predominantly affecting the right ventricle.
