This child had the clinical signs of mild valvar pulmonary stenosis, for which this RV angiogram in RAO was performed. Diastole on the left, systole on the right.
The right ventricle is clearly abnormal. It has a trabeculated apical half which shows increased contractility, reducing to almost nothing on the systolic frame. The basal half is smooth and non-contractile: indeed it enlarges slightly in systole.
At first one might think this is Ebstein's malformation of the tricuspid valve, with the atriallised part of the RV showing typically reduced function. However it is not: the tricuspid valve was easily identified on the full cine run, in a normal position, and only trivially incompetent. Follow through showed a normal looking left ventricle.
This was diagnosed at the time as selective basal endocardial fibroelastosis. With only mild pulmonary stenosis, RV function was not compromised and the valve did not require relief, so the morphology of the RV was never determined. However, since this case I have seen a few examples of the same pattern affecting the left ventricle, and sometimes both. These were in children and teenagers and most presented with congestive heart failure (have you seen Stamp 6 yet?- this was one of them). In those which reached autopsy or explant, the non-contractile bases of the left ventricles did show extensive endocardial fibroelastosis.
These appearances have been described as "two chambered ventricle", a grouping which includes sporadic cases of even more bizzare regional ventricular dysplasia, sometimes verging on aneurysm formation. It is not to be confused with non-compaction.