Pulmonary infarction occurs with all except -
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 the 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, haemorrhages may occur, but there is no infraction 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, haemorrhages are distinguished by the preservation of the pulmonary alveolar architecture; in such cases, resorption of the blood permits reconstitution of the preexisting architecture.
Saddle embolus at bifurcation
Blockage of 2nd and 3rd gen end arteries
Arterioles are blocked
None