Congestive heart failure is a condition in which the heart is so weakened that it is not strong enough to pump blood to maintain normal circulation. The lungs may become congested, and the blood may push back into the veins supplying blood to the heart. Fluid may escape from the blood into the tissues, causing the ankles to become puffy and swollen.

Causes of CHF include high blood pressure, coronary heart disease, and congenital birth defects to the heart.