The dilated heart here means large cardiac shadow on chest X ray.This may be actual or as a result of technical error while taking film. In AP(anteroposterior) film heart looks bigger. The true measurement is around more than 50 to 60% of maximum chest width.
If enlarged it is due to heart dysfunction the causes of which may be outside the heart(anemia,hypertension
) or with in the heart( disease of any of three layers of heart pericardium, myocardium, endocardium,: valves or electrical disturbances in heart)
A complete workup by a team of pediatrician
and pediatric cardiologist along with pediatric cardiac surgeon
Most of such disorders are treatable and treatment modalities are available at many centres of country.