What causes pulmonary edema?
1. Heart failure
The most common cause of pulmonary edema is congestive heart failure. Typically, the heart pumps blood from the lungs into the aorta, the biggest blood vessel in the body.
A diseased heart, however, may not pump the blood efficiently. Thus, with each heartbeat, more and more blood accumulates in the heart’s left ventricle. This excessive volume causes the pressure to increase in the pulmonary veins, the vessels that transport blood from the lungs to the heart. Eventually, the pressure becomes so excessive that a lot of blood stays in the lung vessels, and then moves into the air spaces.