A 75 year old man who had been on bed rest for the past 14 days, complains of breathlessness and chest pain. The chest X-ray is normal. The next investigation should be:
Lung ventilation-perfusion scan
Pulmonary aeriography
Pulmonary venous angiography
Echocardiography
This patient might be having pulmonary embolism, for which Pulmonary aeriography is diagnostic. Actually Chest CT with contrast has viually replaced invasive pulmonary angiography as a diagnostic test. Lung scanning has become a second-line diagnostic test for PE, used mostly for patients who cannot tolerate intravenous contrast. Echocardiography is not a reliable diagnostic imaging tool for acute PE because most patients with PE have normal echocardiograms. Ref: Harrisons principles of internal medicine, 18th edition, chapter 262.