The shape and function of the right ventricle in Ebstein's anomaly

Ebstein's anomaly involves both the right ventricle (RV) and tricuspid valve.

The functional RV and tricuspid orifice were traced from magnetic resonance images in 29 adult Ebstein patients and 9 normal subjects and reconstructed for visualization and measurement of regional RV size, function, and shape at 20 cross sections, and inlet and outflow tract ejection fractions (EFs).

The RV in Ebstein's had RV dilation (end diastolic volume index 179 ± 69 vs. 84 ± 22 ml/m(2) in normals, p<0.001) and global dysfunction (EF 45 ± 8 vs. 55 ± 5% in normals, p<0.001). Longitudinal contraction was preserved (26 ± 13 vs. 26 ± 4 mm in normals) and correlated more weakly with EF than short axis fractional shortening (r=0.44 vs. r=0.71, p<0.05 for both). The apical region in Ebstein's RV was enlarged, rounded and contributed more than normal to the global stroke volume. However this contribution correlated inversely with global EF. In contrast slices in the basal region had normal cross sectional area and their function correlated directly with global EF. Inlet EF was depressed (46 ± 8% vs. 55 ± 6 in normals, p=.002); outflow tract EF was even more depressed (39 ± 14, p=0.019).

The three dimensional shape of the RV in adult Ebstein patients was demonstrated. The Ebstein's RV remodels in diverse regional patterns rather than following a shape continuum. Changes at the apex and base had opposing effects on function. Global EF was supported more by short axis than longitudinal contraction.