CARDIOMEGALY, X_RAY. CARDIOMEGALY, X_RAY Cardiomegaly is an enlargement of the heart due to dilatation of the heart cavities. This can result from many conditions including a disease of the heart muscle myocardial disease, defective valve function, or hypertrophy of the heart muscle due to stenosis of the aortic valve. Pericardial effusion fluid collection in the fibrous envelope of the heart can also lead to considerable cardiomegaly visible on the x_ray. Left untreated, cardiomegaly can lead t