Mitral valve anomalies associated with Ebstein's malformation of the tricuspid valve.

The original description of Ebstein's anomaly mentioned a mild deformity of the mitral valve. Reviews of large series of cases with Ebstein's malformation have, however, tended to omit reference to accompanying mitral valve malformations. We have compared the mitral valves in 19 specimens with Ebstein's malformation with those in 30 age-matched controls in order to determine the prevalence and nature of these anomalies. In the Ebstein's group the mitral valve was abnormal in 14 hearts with orificial anomalies in four, leaflet anomalies in 11, cord anomalies in 11 and papillary muscle anomalies in 13. In the control group, five cases showed mild shortening of the tendinous cords. Half of the changes found in the Ebstein's group were of moderate or significant degree suggesting a primary involvement of the mitral valve. In time, dynamic alterations within the left ventricle might become superimposed and contribute to the development of clinically significant lesions.