The pulmonary artery carries deoxygenated blood from the heart to the lungs. It is one of the only arteries (other than the umbilical arteries in the fetus) that carries deoxygenated blood.
The main hazard of DVT is acute stage thrombus shedding, which can cause a pulmonary embolism (PE) and acute respiratory distress syndrome when the blood flow blocks the pulmonary artery.