Fetal atrioventricular valve junction in normal fetuses and in fetuses with complete atrioventricular septal defect assessed by 4D volume rendering.

OBJECTIVES

To assess the feasibility and clinical potential of 4D volume rendering of the atrioventricular (AV) valve junction, to standardize the acquisition method, and to display the AV valve junction morphology in normal fetuses and in those with a complete atrioventricular septal defect (AVSD).

METHODS

We performed sonography in 40 normal fetuses and 10 fetuses with complete AVSD, and volume datasets were acquired from apical and lateral four-chamber views. The render box was placed systematically. First, it included the AV valves, with the reference dot at the level of the crux of the heart. Then, it included the papillary muscles, with the reference dot in the interventricular septum at the level of the distal opening of the tricuspid valve leaflet.

RESULTS

Volume acquisition and rendering were technically possible in all cases. Volume rendering of the left ventricle showed the position of the anterolateral and posteromedial papillary muscles in 36/40 normal fetuses (90%). At the level of the right ventricle, the septal, anterior and posterior papillary muscles were visualized in 33/40 normal fetuses (82%). In cases of complete AVSD, the AV valve has five leaflets, with anterosuperior and posteroinferior bridging leaflets straddling the septa. The morphology of the anterosuperior bridging leaflets and the abnormal position of the papillary muscles could be displayed in all cases.

CONCLUSIONS

Our study suggests that some of the components of the AV junction can be reconstructed easily from sonographic volumes acquired from an apical or lateral four-chamber view. This new technique may have a role in obtaining views that are not easily accessible by standard sonography, enabling a rapid complementary assessment of normal and abnormal intracardiac anatomy.