Chest X-ray Abnormalities
Heart contour abnormalities

Key points

  • If there is cardiomegaly then 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

Cardiomegaly and heart failure

The heart size should be assessed on every chest radiograph. The heart is enlarged if the cardiothoracic ratio (CTR) 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 lines (or Kerley B lines), and pleural effusions.

Signs of heart failure

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Signs of heart failure

  • Cardiomegaly CTR = 18/30 (>50%)
  • 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

Septal (Kerley B) lines

Septal lines – also known as Kerley B lines – are due to thickening of the interlobular septa which separate the secondary lobules at the periphery of the lungs. They may be very subtle, but if seen in the context of clinical suspicion of heart failure, then septal lines are a strong indicator of interstitial oedema.

Conditions which limit lymphatic flow within the lungs – such as lymphangitis carcinomatosa or sarcoidosis – may also cause septal lines.

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 are a specific sign of interstitial oedema in the context of suspected heart failure

Differential diagnosis

  • If there is no clinical suspicion of heart failure, then conditions that cause lymphatic obstruction – such as sarcoidosis or lymphangitis carcinomatosa – should be considered a possible cause of septal lines

Heart chamber enlargement

If the heart is enlarged 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.

Left atrial enlargement

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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 (highlighted area)
  • Slight bulge in the left heart border (asterisk) 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 as pericardial effusions or aneurysms.