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Chest X-Ray

Mediastinal Size

February 15th, 2021

Mediastinal Widening

  • Look For

  • The mediastinal contour measuring more than 8cm at the level of the aortic arch.
Note that the mediastinum will be artificially widened on an AP film, and this should only be assessed on a PA film.
  • Causes of Mediastinal Widening

  • Lymphadenopathy - infection, sarcoidosis, malignancy
  • Mediastinal tumour - lymphoma, thymoma, metastasis
  • Vascular pathology - thoracic aortic aneurysm, tortuosity of the aorta, aortic rupture
  • Pneumomediastinum
  • Retrosternal goitre
  • Hiatus hernia


  • Look For

  • The cardiac shadow accounting for more than 50% of the chest width.
Note that the cardiac shadow will be artificially widened on an AP film, and this should only be assessed on a PA film.
  • No Overlay
  • Causes of Cardiomegaly

  • Dilated Cardiomyopathy

  • Familial dilated cardiomyopathy
  • Ischaemic heart disease
  • Infection - viral myocarditis, HIV, trypanosomiasis
  • Toxins - alcohol, cocaine, anthracyclines, trastuzumab
  • Connective tissue disease - scleroderma, systemic lupus erythematosus
  • Tachycardia-mediated cardiomyopathy
  • Peripartum cardiomyopathy
  • Left Ventricular Hypertrophy

  • Physiologic - athletes, pregnancy
  • Hypertensive heart disease
  • Valvular disease - aortic stenosis, aortic regurgitation, mitral regurgitation
  • Hypertrophic (obstructive) cardiomyopathy
  • Aortic coarctation
  • Right Ventricular Hypertrophy

  • Cor pulmonale - pulmonary arterial hypertension, chronic lung disease, chronic pulmonary embolism
  • Valvular disease - tricuspid regurgitation, mitral stenosis
  • Congenital heart disease - atrial septal defect, ventricular septal defect, tetralogy of Fallot
  • Constrictive pericarditis
  • Other

  • Large pericardial effusion
  • Infiltrative disease - haemochromatosis, amyloidosis, sarcoidosis
  • Hyperdynamic state - anaemia, hyperthyroidism, obesity, AV fistula
  • Arrhythmogenic right ventricular cardiomyopathy
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