Adaptation of Left Ventricular Function and Myocardial Microstructure in Fetuses with Right Ventricular Hypoplasia.

Background: This study aimed to evaluate changes in left ventricular (LV) function and myocardial microstructure in fetuses with right ventricular hypoplasia (RVH) using two-dimensional speckle tracking echocardiography (2D-STE), diffusion tensor cardiovascular magnetic resonance imaging (DT-CMR) and proteomics analysis.
Methods: 51 singleton fetuses diagnosed with RVH and 51 normal fetuses were retrospectively included. LV global longitudinal strain (GLS) and global circumferential strain (GCS) were acquired by 2D-STE. Fraction anisotropy (FA), mean diffusivity (MD) and helix angle were measured using DT-CMR in four fetal specimens with RVH and three normal fetal specimens. Bioinformatics analysis was performed for differentially expressed proteins between RVH and normal specimens.
Results: In RVH fetuses, LVGLS and regional longitudinal strain were significantly lower than in controls (p<0.001), whereas LV sphericity index and LVGCS were increased. In RVH fetuses, FA was higher in middle and apical segments than in normal fetuses (p<0.001). LV MD was reduced in all the segments (p<0.001). Circumferentially oriented myocytes and left-handed oriented myocytes were increased, but right-handed orientated myocytes were decreased (p<0.001). Using proteomics, 95 myocardial proteins differed with upregulation of 66 and downregulation in RVH, hearts including myocardial contractile fibrillar proteins and cell membrane protein complexes.
Conclusions: In fetal RVH, the left ventricle demonstrates altered function with reduced longitudinal but augmented circumferential strain which may support its need to augment its preload and consequent cardiac output. Decreased right-handed and increased circumferentially oriented myocytes may contribute to this adaptation. The left ventricle in fetal RVH also demonstrates a differential expression of various myocardial proteins.
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