PathologyPulmonary embolism and infarction
Pulmonary embolism usually originating from thrombus in the veins of the pelvis or lower extremities is very common, especially in bedridden patients who have undergone major surgery. In most patients, the flow of blood through the bronchial circulation is sufficient to prevent the occurrence of tissue necrosis and infarction. In patients with heart failure and reduced oxygenation, the bronchial circulation may not be sufficient, so that pulmonary infarction occurs.
The findings on a standard chest radiograph will depend on whether infarction or bleeding is present, and may be described as follows:
Chest radiograph in pulmonary embolism
1) Embolism without infarction
a) Without bleeding
No pathological changes
Elevation and reduced mobility of ipsilateral dome of diaphragm
Narrowing of vessel shadows peripheral to the embolus
Blunting of the costophrenic angle by pleural fluid (confirmed by lateral
decubitus view)
b) With bleeding
Diffuse, indistinct opacity which is rapidly absorbed
2) Embolism with infarction
Basal pyramidal or hemispherical opacity with the base towards the
pleura and the tip pointing to the hilum (Hampton's hump)
Healed infarct or bleeding may be seen as residual linear opacities, often combined with pleural involvement such as a blunted costophrenic angle and pleural thickening.
The findings on standard chest radiographs are not specific and isotope scanning or angiography is needed to confirm the diagnosis. Ultrasonography or phlebography should be used to identify deep venous thrombosis of the lower extremities.
Isotope scanning, perfusion and ventilation scintigraphy are useful, as areas with reduced perfusion and normal ventilation are typical of pulmonary embolism (Fig. 52 a + b) (see Modalities). If there is uncertainty, pulmonary angiography can be done. This is the most accurate method for identifying dot in the individual pulmonary arteries (see Modalities).
Alf Kolbenstvedt, Arnulf Skjennald and Charles B. Higgins