Left Ventricular Vortex Characteristics in Fetuses With Coarctation of the Aorta by Blood Speckle-Tracking Echocardiography.

OBJECTIVES: The aims of this study were to assess the vortex characteristics of left ventricle (LV) in fetuses with coarctation of the aorta (CoA) using high-frame rate ultrasound with blood speckle-tracking (BST) and explore its relationships with cardiac function and morphology parameters. METHODS: Thirty fetuses with CoA and 30 gestational-age matched normal fetuses were included in this cross-sectional study. The area, length, width, and position of the vortex in the LV were recorded and quantitatively analyzed by BST echocardiography. The associations of vortex properties with ventricular function and morphology were also determined. RESULTS: Based on BST imaging, the LV vortex can be observed in 93% of the fetuses. The fetuses with CoA exhibited significantly larger and wider vortex than the controls (P < .05). Linear regression analysis indicated that vortex area was positively related to sphericity index of LV as well as isovolumic relaxation time (r = .52, P = .003 and r = .42, P = .021). There was a negative correlation between vortex area and mitral valve size (r = -.443, P = .014). No significant association was found between vortex area and myocardial performance index and aortic isthmus size. CONCLUSIONS: It is feasible to quantitatively evaluate the left ventricular vortex in fetuses by BST. The fetuses with CoA exhibited greater vortex area and width, and the altered vortex property is associated with geometry of LV. This will facilitate our comprehension of the unique flow patterns and early cardiac remodeling in fetuses with CoA.

Evaluation of fetal foramen ovale blood flow by pulsed Doppler ultrasonography combined with spatiotemporal image correlation : To define the normal reference range of fetal foramen ovale blood volume for each gestational age: a cross-sectional study.

OBJECTIVE: The objective of this study was to determine fetal foramen ovale blood flow utilizing pulsed Doppler combined with spatiotemporal image correlation. METHODS: A cross-sectional study was performed in 440 normal fetuses between 20 and 40 weeks of gestation. In order to calculate foramen ovale blood flow, the foramen ovale flow velocity-time integral was obtained by pulsed Doppler ultrasonography, and the foramen ovale area was measured by using spatiotemporal image correlation rendering mode. Foramen ovale blood flow was calculated as the product of the foramen ovale area and the velocity-time integral. RESULTS: Gestational age-specific reference ranges are given for the absolute blood flow (ml/min) of foramen ovale, showing an exponential increase from 20 to 30 weeks of gestation, and a flat growth trend during the last trimester, while the weight-indexed flow (ml/min/kg) of foramen ovale decreased significantly. The median weight-indexed foramen ovale blood flow was 320.82 ml/min/kg (mean 319.1 ml/min/kg; SD 106.33 ml/min/kg). CONCLUSIONS: The reference range for fetal foramen ovale blood flow was determined from 20 to 40 weeks of gestation. The present data show that the volume of foramen ovale blood flow might have a limited capacity to increase during the last trimester.

Maturation Fetus Ascending Aorta Elastic Properties: Circumferential Strain and Longitudinal Strain by Velocity Vector Imaging.

Objective: This study aimed to assess the circumferential and longitudinal strain of the fetal ascending aortic (AA) wall and establish a gestational age-associated longitudinal reference for aortic wall strain during the second half of pregnancy. Methods: Singleton fetuses with gestational age (GA) at 20 + 0 to 24 + 6 weeks were prospectively collected from a low-risk population. Global circumferential strain (GCS) and mean longitudinal strain (MLS) of the ascending aorta were measured serially at 4-week intervals using the velocity vector imaging (VVI) technique. Fractional polynomials were conducted to obtain the best-fitting curves between GA and AA strains. GA-specific reference percentiles of GCS and MLS were established by multilevel modeling. Results: A total of 223 fetuses with a total of 1,127 serial observations were enrolled. GCS presented a second-degree fractional polynomial smoothing regression along GA (R 2 = 0.635, P < 0.05). Fetal aortic GCS remained unchanged at ~27.29% (20.36-35.6%) before 31 weeks and increased significantly from 31.36% (26.38-37.12%) at 31 weeks to 43.29% (30.5-56.78%) at term. MLS presented a third-degree fractional polynomial smoothing regression along GA (R 2 = 0.465, P < 0.05). MLS remained steady at ~10.03% (3.28-17.62%) between 20 and 31 weeks and then increased significantly from 12.68% (7.42-20.1%) at 32 weeks to 17.5% (9.67-25.34%) at term. The GCS was significantly higher than the MLS in the ascending aorta wall (p < 0.001). Conclusion: The fetal ascending aorta wall demonstrates obviously greater circumferential strain than longitudinal strain. Both strains remained steady before the late trimester and then gradually increased until delivery, suggesting progressive maturation of aortic elasticity mechanics.