Cor pulmonale is enlargement of the right side of the heart, which pumps blood to the lungs. This enlargement occurs when the heart has to work harder to pump blood through damaged lungs, such as when a person's lungs are damaged because of chronic obstructive pulmonary disease (COPD).

People with cor pulmonale are short of breath because of their damaged lungs. They may have swollen legs and a swollen abdomen because of fluid retention (edema). With time, cor pulmonale leads to heart failure.