Zhong Xin, Luo Yuanchen, Zhou Dan, Liu Minghui, Zhou Jiawei, Xu Ran, Zeng Shi
Department of Ultrasound, Hunan Provincial People's Hospital (The First Affiliated Hospital of Hunan Normal University), Changsha, China.
Department of Ultrasound Diagnosis, The First Hospital of Changsha, Changsha, China.
Front Cardiovasc Med. 2022 Feb 28;9:840494. doi: 10.3389/fcvm.2022.840494. eCollection 2022.
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.
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.
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 ( = 0.635, < 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 ( = 0.465, < 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 ( < 0.001).
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.
本研究旨在评估胎儿升主动脉（AA）壁的圆周应变和纵向应变，并建立妊娠后半期主动脉壁应变与孕周相关的纵向参考标准。
前瞻性收集孕周（GA）为20 + 0至24 + 6周的单胎胎儿，来自低风险人群。使用速度向量成像（VVI）技术，每隔4周连续测量升主动脉的整体圆周应变（GCS）和平均纵向应变（MLS）。采用分数多项式来获得GA与AA应变之间的最佳拟合曲线。通过多水平建模建立GCS和MLS的GA特异性参考百分位数。
共纳入223例胎儿，总计1127次连续观察。GCS沿GA呈现二次分数多项式平滑回归（ = 0.635， < 0.05）。31周前胎儿主动脉GCS保持在约27.29%（20.36 - 35.6%）不变，从31周时的31.36%（26.38 - 37.12%）显著增加至足月时的43.29%（30.5 - 56.78%）。MLS沿GA呈现三次分数多项式平滑回归（ = 0.465， < 0.05）。20至31周期间MLS保持稳定在约10.03%（3.28 - 17.62%），然后从32周时的12.68%（7.42 - 20.1%）显著增加至足月时的17.5%（9.67 - 25.34%）。升主动脉壁的GCS显著高于MLS（ < 0.001）。
胎儿升主动脉壁的圆周应变明显大于纵向应变。两种应变在妊娠晚期前保持稳定，然后逐渐增加直至分娩，提示主动脉弹性力学逐渐成熟。
