Impaired Distensibility of the Proximal Aorta in Fetuses With Tetralogy of Fallot

Background Increased aortic wall stiffness, which even persists after repair, has been reported in patients with tetralogy of Fallot (TOF). We aimed to observe the distensibility of the ascending aorta and descending aorta in fetuses with TOF and explore its relation with aortic blood flow volume and aortic and pulmonary annular size. Methods and Results Twenty-three fetuses with TOF and 23 gestational age-matched normal fetuses were included in this prospective cross-sectional study. The distensibilities of the ascending aorta and descending aorta were assessed by aortic strain (AS), which was defined as follows: 100×(maximum internal diameter in the systolic phase-minimum internal diameter in the diastolic phase)/minimum internal diameter in the diastolic phase. The maximum internal diameter in the systolic phase and minimum internal diameter in the diastolic phase of the ascending aorta and descending aorta were measured by M-mode echocardiography. Associations between AS and aortic blood flow volume and aortic and pulmonary valve diameters were assessed in both groups. AS of the ascending aorta in TOF group was lower than that in controls (20.48%±4.19% versus 28.17%±4.54%; P<0.001), whereas there was no significant difference in the descending aorta. The multivariate regression model demonstrated that AS was significantly related to aortic valve size (P=0.014) and aortic blood flow volume (P=0.022) in fetuses with TOF, whereas only aortic blood flow volume was significantly correlated with AS in the control group (P=0.01). No significant association was found between AS and pulmonary valve size. Conclusions Impaired distensibility of proximal aorta was observed in fetuses with TOF. Both intrinsic abnormalities of the aortic wall and aortic volume overload probably play roles in the altered aortic distensibility.