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

In this study we evaluated changes in left ventricular (LV) function and myocardial microstructure in fetuses with right ventricular hypoplasia (RVH) using 2-dimensional speckle tracking echocardiography, diffusion tensor cardiovascular magnetic resonance imaging, and proteomics analysis.

Fifty-one singleton fetuses diagnosed with RVH and 51 normal fetuses were retrospectively included. LV global longitudinal strain and global circumferential strain were acquired using 2-dimensional speckle tracking echocardiography. Fraction anisotropy, mean diffusivity, and helix angle were measured using diffusion tensor cardiovascular magnetic resonance imaging in 4 fetal specimens with RVH and 3 normal fetal specimens. Bioinformatics analysis was performed for differentially expressed proteins between RVH and normal specimens.

In RVH fetuses, LV global longitudinal strain and regional longitudinal strain were significantly lower than in controls (P < 0.001), whereas LV sphericity index and LV global circumferential strain were increased. In RVH fetuses, fraction anisotropy was higher in middle and apical segments than in normal fetuses (P < 0.001). LV mean diffusivity was reduced in all of the segments (P < 0.001). Circumferentially oriented myocytes and left-handed oriented myocytes were increased, but right-handed oriented 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.

In fetal RVH, the left ventricle demonstrates altered function with reduced longitudinal but augmented circumferential strain, which might support its need to augment its preload and consequent cardiac output. Decreased right-handed and increased circumferentially oriented myocytes might contribute to this adaptation. The left ventricle in fetal RVH also demonstrates a differential expression of various myocardial proteins.