Abnormal flow patterns in ascending aorta in fetuses with tetralogy of Fallot: evaluation by blood speckle-tracking echocardiography.

Abstract

To evaluate the blood flow pattern in the ascending aorta (AAo) of fetuses with tetralogy of Fallot (ToF) using high-frame-rate ultrasound with blood speckle-tracking echocardiography (BST), and to investigate its relationship with cardiac geometry. Included in this cross-sectional study were 35 fetuses with ToF and 35 gestational-age-matched normal fetuses (controls) who underwent routine obstetric ultrasound examination and complete echocardiography between April 2022 and August 2023. Flow patterns in the AAo were recorded and assessed using BST in all fetuses. Left ventricular (LV) inflow and outflow tract angle (IOA) was measured in both groups. The association between the presence and number of vortices in the AAo and cardiac geometry in the ToF group was also determined. On BST, at a median gestational age of 24.9 (interquartile range (IQR), 23.7-28.7) weeks for all fetuses, vortex flow in the AAo was detected in 91.4% (32/35) of fetuses with ToF and 17.1% (6/35) of normal fetuses (P < 0.001). Compared with the controls, the median number of vortices in the AAo was significantly higher in fetuses with ToF (1 (range, 0-3) vs 0 (range, 0-1); P < 0.001). There was no significant difference in vortex duration between the two groups. The fetuses with ToF exhibited significantly smaller median LV-IOA compared with the control fetuses (36.06° (IQR, 32.55°-41.24°) vs 42.90° (IQR, 36.30°-46.37°); P = 0.006). Correlation analysis indicated that the presence of vortices was associated significantly with aortic valve size in fetuses with ToF (r = 0.54 (P = 0.001)), as well as the LV-IOA (r = - 0.376 (P = 0.026)). The number of vortices correlated significantly with aortic valve size (r = 0.476 (P = 0.004)). There was no correlation between the presence and number of vortices and pulmonary valve size. On BST, fetuses with ToF exhibited a higher incidence and a greater number of blood flow vortices in the AAo compared with gestational-age-matched controls. The association between the abnormal flow pattern in the AAo and LV outflow tract morphology, as well as cardiac geometry, may help to elucidate the pathophysiology of the aorta in fetuses with ToF. © 2025 International Society of Ultrasound in Obstetrics and Gynecology.