The functional right ventricle and tricuspid regurgitation in Ebstein's anomaly

The size of the functional right ventricle of patients with Ebstein's anomaly is, according to contemporary opinion, small. However, the in vivo size of the functional right ventricle in patients with Ebstein's anomaly is unknown. Furthermore, it is unknown how the apical displacement and regurgitant fraction of the tricuspid valve in Ebstein's anomaly affects the size of the functional right ventricle. Therefore the primary aim of this study was to determine the volume of the functional right ventricle in patients with Ebstein's anomaly. The secondary aim of this study was to assess correlation of the volume of the functional right ventricle to the apical displacement and regurgitant fraction of the tricuspid valve.

Thirty-two consecutive patients with Ebstein's anomaly without previous cardiac surgery or shunts were studied prospectively by cardiovascular magnetic resonance. Functional right ventricle, left ventricle, and atrialized right ventricle volumes and tricuspid valve regurgitation were measured.

Functional right ventricle end diastolic volumes were median 127 ml/m² (range: 76-339 ml/m²) and were median 2.5 (range: 1.3-8.8) times larger than the left ventricle volumes. Furthermore, functional right ventricle volumes correlated in a strong positive fashion with tricuspid valve regurgitation (p<0.001, R(2)=0.65) and modestly with the atrialized right ventricle volumes (p=0.027, R(2)=0.16).

Patients with untreated Ebstein's anomaly have large functional right ventricles. The size of the enlarged functional right ventricle seems to depend on the degree of tricuspid valve regurgitation and not on the size of the atrialized right ventricle or the age of the patient.