Correct Answer - D
Ans. is 'd' i.e., None
The morphologic consequences of embolic occlusion of the
pulmonary arteries depend on the size of the embolic mass and the
general state of the circulation.
Large emboli may impact in the main pulmonary artery or its major
branches or lodge at the bifurcation as a saddle embolus. Sudden
death often ensues, owing largely to the blockage of blood flow
through the lungs. Death may also be caused by acute failure of the
right side of the heart (acute cor pulmonale).
Smaller emboli can travel out into the more peripheral vessels,
where they may cause infarction. In patients with adequate
cardiovascular function, the bronchial arterial supply can often
sustain the lung parenchyma despite obstruction to the pulmonary
arterial system. Under these circumstances, hemorrhages may
occur, but there is no infarction of the underlying lung parenchyma.
Only about 10% of emboli actually cause infarction. Although the
underlying pulmonary architecture may be obscured by the suffusion
of blood, hemorrhages are distinguished by the preservation of the
pulmonary alveolar architecture; in such cases, resorption of the
blood permits reconstitution of the preexisting architecture.