Sometimes, people who have heart failure don't even know it until the problem progresses to a more serious form, called congestive heart failure. With less blood leaving the heart, the returning blood gets backed up and the resulting increase in pressure causes seepage into surrounding tissues. This can lead to swelling, usually of the legs, ankles, or feet. In some cases, fluid seeps into vital organs, such as the lungs and liver. When fluid builds up in the lungs, breathing is difficult.
Heart failure occurs under a number of circumstances.
The most common cause is damage to the heart resulting from a heart attack. Other causes include narrowing of blood vessels, weakening of the heart caused by high blood pressure, leaking heart valves, birth defects, alcohol use, diabetes, and viral infections. Weight gain and ankle swelling may occur. Fatigue and increased urination at night are common. A person who has heart failure may awaken suddenly from a sound sleep gasping for breath.