Investigation of heart failure assesses pulmonary congestion, rhythm, underlying cardiac disease, complications and prognosis.
Erect chest radiography
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An erect chest X-ray should be performed in all cases.
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Findings may include distension of upper lobe pulmonary veins, more prominent lung-field vascularity and dilated pulmonary arteries.
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Subsequent interstitial oedema thickens interlobular septa and dilates lymphatics, producing horizontal septal or Kerley B lines in the costophrenic angles.
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More advanced alveolar oedema causes hazy opacification spreading from the hila and pleural effusions.
Electrocardiography and echocardiography
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An electrocardiogram should be performed to assess for atrial fibrillation or atrial flutter.
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Echocardiography should be considered in all patients with heart failure to determine the aetiology.
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Echocardiography detects valvular disease, including occult mitral or aortic stenosis, and other potentially treatable conditions.
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It also identifies patients who may benefit from long-term drug therapy and cardiac device implantation.
Blood investigations
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Serum urea, creatinine, electrolytes, haemoglobin and thyroid function help establish the nature and severity of underlying disease and detect complications.
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BNP is elevated in heart failure and is a prognostic marker.
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BNP also helps differentiate heart failure from other causes of breathlessness or peripheral oedema.