Pulmonary arteries transport oxygen-depleted blood from the right ventricle to the lungs. Pulmonary embolism is a blockage in one of the pulmonary arteries. This generally occurs when a blood clot (embolus) travels from the leg to the lung. Since pulmonary embolism almost always occurs in combination with deep vein thrombosis (DVT), the conditions are often referred to as venous thromboembolism.
Although anyone can develop DVT and pulmonary embolism, factors that increase your risk include: immobility, medications, smoking, genetic predisposition, an increased number of red blood cells (polycythemia), cancer, pregnancy, surgery and damage to blood vessel walls.
Pulmonary embolism can lead to pulmonary hypertension. Pulmonary hypertension is when the blood pressure in your pulmonary arteries increases. This happens because the obstruction in the pulmonary arteries makes it harder for the lower right side of your heart (right ventricle) to push blood through the lungs.