The heart is made of four chambers that form two pumps. Each of the pumps include an upper atrium and a lower ventricle. The right atrium receives deoxygenated (no oxygen) blood from the veins and sends it to the right ventricle, where it is pumped through the lungs to become oxygenated (oxygen filled). Oxygenated blood returns to the heart via the left atrium, enters the left ventricle and is pumped around your body in arteries. During heart failure, the left ventricle does not empty itself of blood effectively. This can lead to a pressure increase in the upper atrium chamber and local veins. The backlog of blood in the heart triggers fluid retention in the lungs, causing shortness of breath. In right-sided heart failure, blood pools in the veins, causing swelling in the tissues, particularly the legs and abdominal organs. This can affect the kidneys, altering their function and causing the body's retention of salt and water. Heart failure can be caused by several other medical conditions: coronary artery disease and heart attack; hypertension; faulty heart valves; cardiomyopathy; myocarditis; congenital heart defects; heart arrhythmias, and; thyroid disease.
