Heart failure

Illustration of a person with heart failure

Heart failure occurs when your heart muscle doesn't pump blood as well as it should. When your heart doesn't pump enough blood to meet your needs, blood often backs up and causes fluid to build up in your lungs (congest) and in your legs, causing your legs to swell and turn blue from lack of oxygenated blood flow (cyanosis). This fluid in your lungs can make you short of breath. Some types of heart failure can lead to an enlarged heart.