If heart failure affects the left side of the heart, the heart cannot pump enough oxygen-rich blood to the rest of the body. If it affects the right side, the heart cannot pump enough blood to the lungs to pick up oxygen. When the heart is weakened by heart failure, blood and fluid can back-up into the lungs and fluid builds up in the feet, ankles and legs. People with heart failure often experience tiredness, dizziness, shortness of breath and a cough that is worse when lying down.
Attribution: Straight Talk Foundation