The posterior descending artery (PDA) is a blood vessel that supplies oxygen-rich blood to the heart muscle. It typically branches off from the right coronary artery in most individuals and runs along the back of the heart. The PDA plays a crucial role in nourishing the inferior part of the heart, particularly the ventricles. In some people, the PDA may arise from the left coronary artery, a condition known as left dominance. The health of the PDA is important, as blockages can lead to serious heart conditions, including myocardial infarction (heart attack) and other cardiovascular diseases.