Heart failure is a condition that occurs when the muscles in the heart fail to pump out enough blood to help maintain normal functioning of the body. Due to this insufficient supply of blood, your body develops a blood and fluid buildup over some time. Usually, the fluid buildup takes place in the lungs and causes swelling over the body. As a result, your body gets deprived of the essential functioning element oxygen, causing shortness of breath and several complications in various organ systems.