Coronary artery blood flow velocities in various fetal conditions

Objective: To determine fetal coronary artery peak blood flow velocities in normal and high-risk pregnancies. Methods: Coronary artery peak systolic and diastolic blood flow velocities were measured by pulsed-wave Doppler velocimetry after identification of the coronary arteries by color Doppler imaging. Peak blood velocities obtained from normal pregnancies were related to gestational age using linear regression analysis. Blood flow velocities in normal fetuses were compared to measurements obtained in various fetal conditions. Results: In normal fetuses coronary artery blood flow was visualized at a median gestational age of 33 + 6 weeks; median systolic and diastolic peak blood flow velocities were 0.21 and 0.43 m/s, respectively, and showed no significant change with gestational age. In growth-restricted fetuses coronary artery blood flow was visualized significantly earlier in gestation (median 28 + 2 weeks); systolic and diastolic peak blood flow velocities were higher at 0.25 and 0.48 m/s, respectively (P < 0.05). The highest coronary blood flow velocities were observed with fetal anemia. Coronary artery blood flow was also measured in fetuses with ductus arteriosus constriction due to indomethacin. Velocities did not differ from normal fetuses. Both in fetal anemia and ductus arteriosus constriction coronary artery blood flow could no longer be visualized with resolution of the underlying condition. Conclusion: Examination of coronary artery blood flow dynamics in the human fetus demonstrates acute increases in diastolic velocities in severe anemia and ductus arteriosus constriction based on the severity of the condition. In fetuses with growth restriction increased coronary blood flow velocities can be appreciated throughout the cardiac cycle. Clinical correlation in the interpretation of coronary blood flow dynamics in the human fetus is essential.