Fetal cardiac time intervals determined by Doppler echocardiography

Area of Science:

• Cardiovascular Physiology
• Fetal Medicine
• Diagnostic Imaging

Background:

• Doppler echocardiography is crucial for assessing fetal cardiovascular function.
• Understanding normal fetal hemodynamics is essential for detecting abnormalities.
• Gestational age influences fetal cardiovascular parameters.

Purpose of the Study:

• To evaluate the relationship between Doppler-derived hemodynamic parameters and gestational age in normal fetuses.
• To establish normative data for fetal aortic and pulmonary blood flow velocity waveforms.
• To identify parameters that reliably track fetal development.

Main Methods:

• 111 Doppler echocardiographic examinations were performed on 88 normal fetuses (16-41 weeks gestation).
• Assessed parameters included maximal velocity (MV), acceleration time (AT), ejection time (ET), acceleration velocity (AV), and AT/ET ratio.
• Analysis focused on aortic and pulmonary artery blood flow velocity waveforms.

Main Results:

• Aortic MV, pulmonary MV, aortic AT, and pulmonary AT showed significant correlations with gestational age.
• Aortic AT/ET ratio and pulmonary AT/ET ratio also correlated well with gestational age.
• No significant correlations were found between gestational age and aortic AV, aortic ET, pulmonary AV, or pulmonary ET.

Conclusions:

• Maximal velocity and acceleration time of fetal aortic and pulmonary arteries are reliable indicators of gestational age.
• Acceleration velocity and ejection time may be less sensitive to gestational age changes in normal fetuses.
• Observed correlations suggest changes in fetal vascular resistance with advancing gestation.