Congenital Mitral Valve Dysplasia is a condition where the mitral valve (separating the left atrium and left ventricle) did not form correctly at birth.  As a result, the valve does not close (coapt) normally.

This poor coaptation allows reverse blood flow (left ventricle into left atrium), which is termed regurgitation or insufficiency.  

This disease is progressive in that the chambers will continue to dilate, but the valve structure likely will not change.  

Routine rechecks are required to monitor for any changes to the left atrium or ventricle that may warrant additional testing or direct medical management of this disease.  

Eventually, this disease can lead to the development of congestive heart failure (fluid in the lungs), which is a medical emergency that makes breathing very difficult.