A medical animation showing the anterior and coronal views of the heart and lungs with the mechanism of a pulmonary embolism. A pulmonary embolism occurs following the presence of a deep vein thrombosis (DVT) in which an embolus breaks off and travels up the bloodstream. The embolus then breaks into multiple clots, travels through the heart, and becomes lodged in the pulmonary arteries. The pulmonary arteries become blocked and oxygenated blood is no longer exchanged. Anatomy highlighted in this view includes the lungs, aorta, pulmonary artery, heart, inferior vena cava, atriums, and ventricles.