If the muscle of the heart becomes weak or the heart's valves become narrowed or leak, the heart can have more difficulty pumping blood. Less blood flow to the muscles of the body causes weakness and fatigue. Less blood flow through the kidneys causes less urine to be passed. Then fluid builds up in the legs and other parts. These changes cause symptoms of fatigue and shortness of breath, and may mean heart failure is present.
Heart failure is common.
Although heart failure can occur at any age, diseases of the heart and blood vessels usually become worse over many years. So heart failure occurs most in older people. Heart failure is a very common cause of shortness of breath, weakness, fatigue and swelling of the ankles. The symptoms can all happen together in the one person. More often, only one or two of the symptoms may appear in the early stages of heart failure.