Investigations

• blood count ^d
• urea, electrolytes, and creatinine ^a
• cardiac enzymes ^d
• B-natriuretic peptide ^a
• arterial blood gas if dyspnoeic
• ECG ^b  looking for: ^b
  • anterior Q waves ^b  
  • left-bundle branch block ^b  
• insert a urinary catheter to monitor urine output ^d
• chest X-ray ^b looking for: ^b  
  • cardiomegaly
  • interstitial oedema
  • inverted pulmonary blood-flow distribution

In cases of clear pulmonary oedema look for ^b  

• pulmonary blood-flow distribution   
  (upper fields predominating make heart failure much more likely)
• pulmonary oedema distribution   
  (even distribution make heart failure more likely; central or patchy distribution makes it less likely)
• vascular pedicle width   
  (a narrow width makes heart failure less likely)

• Consider an echocardiogram ^d