The diagnosis of pulmonary embolism.

A blind assessment of abnormalities of pulmonary scintiscans in patients with pulmonary emboli and other clinical conditions showed that there was no abnormality specific for pulmonary embolism. However, a normal lung scan virtually excluded pulmonary embolism and an area, or areas, of absent perfusion was confirmatory evidence of embolism, without infarction, if the chest radiograph was normal, and of embolism with infarction if the clinical and radiographic findings were compatible. A controlled analysis of biochemical and electrocardiographic abnormalities associated with pulmonary embolism showed that abnormalities of liver function and blood urea were more frequent than in a group of patients suspected of, but not having, emboli. A similar analysis of the electrocardiograms showed that a Q3R3S1 with T wave inversion over the right ventricular leads and lead III (+avf) that developed or regressed was pathognomonic of embolism, but other features were of little value. It is suggested that all hospital patients should have an electrocardiogram performed on admission so that serial changes may be assessed and that lung scanning should be used as a screening test in patients suspected of having pulmonary embolism.