Recognizing Adult Heart Disease

There are normally 15 to 50 cc of fluid in the pericardial space between the parietal and visceral pericardial layers. Abnormal accumulations of fluid begin in the dependent portions of the pericardial space that, in the supine position, is posterior to the left ventricle ( Fig. 11.1A ). As the pericardial effusion increases in size, it tends to accumulate more along the right heart border until it fills the pericardial space and encircles the heart ( Fig. 11.1B ).

CT scans can demonstrate small pericardial effusions, although pericardial ultrasonography is usually the imaging study of first choice. Conventional radiographs are poor at defining a pericardial effusion.

Some of the causes of pericardial effusions are outlined in Box 11.1 .

Sometimes, there is an extracardiac cause of apparent cardiac enlargement on conventional radiography that may cause the cardiothoracic ratio (see Fig. 3.1 ) to appear greater than 50%, while the heart itself may actually be normal in size.

The extracardiac causes of apparent cardiomegaly are outlined in Table 11.1 . Magnification of the heart produced by projection, usually on an antero-posterior (AP), supine, portable chest examination, is the most common cause of apparent cardiomegaly.

So, is it possible to estimate the size of the heart on a portable chest radiograph? The answer is “yes.” A good rule of thumb: If the heart appears enlarged on a well-inspired, portable chest radiograph , it probably is enlarged ( Table 11.2 and Fig. 11.2 ).

Generally speaking, evaluation of cardiac size using conventional radiography is best made on the frontal chest radiograph. To evaluate for the presence of enlargement of the cardiac silhouette in the lateral projection, look at the space posterior to the heart and anterior to the spine at the level of the diaphragm. In a normal person, the cardiac silhouette will usually not extend posteriorly and project over the spine ( Fig. 11.3A ).

As the cardiac silhouette enlarges , whether that enlargement is due to cardiomegaly or pericardial effusion, the posterior border of the heart may extend to, or overlap, the anterior border of the thoracic spine. This can be useful as a confirmatory sign of an enlarged cardiac silhouette ( Fig. 11.3B ).

The incidence of congestive heart failure (CHF) has grown rapidly over the last two decades so that CHF is one of the most common diagnoses in hospitalized patients over the age of 65.

Causes of congestive heart failure

• In the United States, the two most common causes of CHF are coronary artery disease and hypertension .

• Other causes of CHF:

  • Cardiomyopathy , such as from long-standing alcohol abuse

  • Cardiac valvular lesions like aortic stenosis and mitral stenosis

  • Arrhythmias

  • Hyperthyroidism

  • Severe anemia

  • Left-to-right shunts

Typically, congestive heart failure presents with one of two radiographic patterns : pulmonary interstitial edema or pulmonary alveolar edema. Not every feature of each pattern is always present and there is often overlap between the two patterns.