pulmonary infarction

An infarction is the death of tissue starved of its blood supply, the same word used for a heart attack of the heart muscle. A pulmonary infarction is that process in the lung: when an embolus blocks a pulmonary artery, the segment of lung it fed can die for lack of oxygen-rich blood, much as a leaf on a vine withers when its stem is pinched off.

The lung is partly protected from this fate because it has a second blood supply, the bronchial arteries, and because oxygen can also diffuse in from the airways. For these reasons only a minority of pulmonary emboli actually cause infarction, and it tends to happen with smaller, more peripheral clots or when the back-up circulation is already compromised, as in heart failure.

When infarction does occur, it typically causes sharp chest pain worsened by breathing, coughing up blood, and sometimes a small pleural effusion. On a CT scan it may appear as a wedge-shaped area with its base against the lung surface. Many infarcts heal over weeks, sometimes leaving a small scar, while the underlying embolism is treated with anticoagulation.