Pulmonary embolism, artwork - stock illustration

Circulatory system of heart and lungs, computer artwork, showing a thrombus in the right lung. This occurs when one of the pulmonary arteries is blocked, usually by an abnormal blood clot, that have broken off the wall of a vein in the leg or pelvis after forming in deep vein thrombosis. The two branches of the pulmonary artery (red) carry deoxygenated blood from the heart to the lungs. Oxygenated blood returns from the lungs in the two branches of the pulmonary vein (blue-violet).