Cardiomegaly or enlargement of the heart is a common finding on X-rays of the chest. This is a finding which has many causes. One of the most common is congestive heart failure. Other causes include disorders of the heart valves, cardiomyopathy which is disease of the heart muscle with decreased function, heart problems you are born with such as abnormal communication between the heart chambers, myocarditis or inflamed heart muscle, and lung disease such as emphysema or pulmonary embolism (clots to the lung). Pregnancy, anemia, kidney failure and sickle cell disease are some of the others.
The radiologist will often make this diagnosis by eye balling the X-ray instead of precise measurements. The enlargement is often graded as mild, moderate and severe. The cause of the enlarged heart is rarely identified on X-ray. Often other tests such as an ultrasound of the heart called an echocardiogram will be needed. A specialist in the heart or cardiologist will offer further testing, diagnosis and treatment.
Given the wide variety of conditions which can cause an enlarged heart on chest X-ray, it is very important to combine the imaging finding with the clinical history and physical exam findings. Some of the causes of an enlarged heart can cause breathlessness such as heart failure or be life threatening like pulmonary embolism or clots to the lungs. Many others such as heart valve problems or heart muscle disorders can be more chronic.
Sometimes a radiologist can tell which parts or chambers of the heart are enlarged based on the appearance. Other times, a specific diagnosis diagnosis can be offered like with heart failure. In these cases, there will be fluid in the lungs and along the covering of the lung or pleural effusion. In many others, there is no way to tell on X-ray alone. It is also not possible to tell whether the heart became enlarged recently or a long time ago. This is only possible if there are old X-rays available in your file.
Sometimes it is not your heart that is enlarged, but fluid around the heart or pericardial effusion. This will look exactly like an enlarged heart on X-ray. This may need prompt treatment if the fluid developed recently and is causing symptoms. In some cases, a mass abutting the heart can give the appearance of an enlarged heart.
In all cases, it will be very important for your clinical doctors to use all the available information to arrive at the most accurate diagnosis and treatment plan. The X-ray is just a start and alerts your doctors that something may be wrong. Further testing and consultation with specialists will likely be needed.