PULMONARY EMBOLISM - The lodgment of a blood clot in the lumen of a pulmonary artery, causing a severe dysfunction in respiratory function. Pulmonary emboli often have origin in the veins of the lower extremities (clots form in the leg veins and then travel to the lungs in the venous circulation). Symptoms and features include acute onset of shortness of breath, chest pain (worse with breathing), and rapid heart rate and respiratory rate. Some individuals may have a bloody cough. Diagnosis can be made using ventilation perfusion scanning of the lung or pulmonary angiogram.