Pulmonary embolism treatment. X-ray of a section through the abdomen of a 53-year-old patient on anticoagulant medication to help prevent a pulmonary embolism (PE), showing a vena cava filter (faint lines, centre) in place in the vena cava. PE occurs when a blood clot (thrombus) in a vein breaks off and migrates in the blood system to a pulmonary artery, causing a blockage. The blockage causes pulmonary arterial hypertension, heart failure and cardiogenic shock. Vena cava filters are used as preventative measures along with anticoagulant medication in patient's at high risk of developing PE.