Chest x-ray abnormalities

Heart contour abnormalities

Cardiomegaly and heart failure

The heart size should be assessed on every chest radiograph. The heart is enlarged if the cardiothoracic ratio is greater than 50% on a PA view. If the heart is enlarged, check for other signs of heart failure such as pulmonary oedema, septal (Kerley B) lines, and pleural effusions.

Key points

  • If there is cardiomegaly - look for other signs of heart failure
  • It may be possible to determine which chamber is enlarged
  • An obscured heart border may indicate disease of the adjacent lung
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Signs of heart failure

  • Cardiomegaly CTR = 18/30
  • Upper zone vessel enlargement (1) - a sign of pulmonary venous hypertension
  • Pulmonary oedema (2) - bilateral increased lung markings (classically peri-hilar and shaped like bats wings - more widespread in this case)
  • Septal (Kerley B) lines (3) - See next picture
  • Pleural effusions (4)

Clinical information

  • Worsening exercise tolerance
  • Chronic uncontrolled hypertension
  • Rapid onset of shortness of breath
  • Atrial fibrillation

Diagnosis

  • Left ventricular failure with pulmonary oedema
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Septal (Kerley B) lines

Septal lines, also known as Kerley B lines, are due to fluid accumulating between the secondary lobules of the lungs. They are an elusive sign, but once spotted, pulmonary oedema is almost always the cause, especially in a patient with a cardiac history.

Septal lines (Kerley B lines)
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Septal lines (Kerley B lines)

  • Costophrenic angle (detail of above image)
  • Horizontal lines reaching the lung edge

Diagnosis

  • Septal lines - a specific sign of pulmonary oedema

Differential diagnosis

  • Occasionally conditions that cause lymphatic obstruction may cause septal lines - such as sarcoidosis or lymphangitis carcinomatosa

Heart chamber enlargement

If there is cardiomegaly it is sometimes possible to determine which chamber is enlarged. For example, signs of left atrial enlargement include a double right heart border, bulging of the left heart border, and splaying of the carina to greater than 90 degrees.

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Left atrial enlargement

  • The left and right heart borders are marked (arrows)
  • Extra right heart border - formed by the edge of the enlarged left atrium (blue area)
  • Slight bulge in the left heart border (*) due to enlargement of the left atrial appendage
  • Splaying of the carina to greater than 90 degrees - the carina lies directly above the left atrium

Clinical information

  • History of rheumatic heart disease and cardiac surgery - note the sternotomy wires and prosthetic aortic and mitral heart valves (arrowhead)

Diagnosis

  • Cardiomegaly with left atrial enlargement due to chronic mixed mitral valve disease

Abnormal heart contours

The cardiac contour may be abnormal due to congenital heart disease, such as atrial or ventricular septal defects, or due to acquired abnormalities such pericardial effusions or aneurysms.

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Left ventricular aneurysm

  • AP erect chest x-ray
  • Heart clearly enlarged despite the AP view
  • Bulging left heart border
  • Circular rim of calcification (arrowheads)

Clinical information

  • Previous myocardial infarction

Diagnosis

  • Left ventricular aneurysm - an uncommon complication of myocardial infarction

Obscured heart contours

An obscured heart border may be due to disease of the adjacent lung. Just as right middle lobe consolidation obscures the right heart border (right atrial edge), so consolidation of the lingula (an anterior segment of the left upper lobe) leads to an obscured left heart border (left ventricular edge).

Consolidation of the lingula
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Consolidation of the lingula

  • Bilateral lower zone consolidation
  • Poorly defined left heart border - indicates lingular involvement
  • The left hemidiaphragm is also poorly defined - indicates left lower lobe involvement

Clinical information

  • Smoker with known Chronic Obstructive Pulmonary Disease (COPD)
  • Productive cough
  • Raised white cell count

Diagnosis

  • Pneumonia - exacerbating COPD

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