general condition in which the heart muscle does not contract and relax effectively, thereby reducing the performance of the heart as a pump and compromising blood circulation throughout the body. Heart failure is not a specific disease but the result of many different underlying conditions, such as myocardial infarction ( heart attack), hypertension (high blood pressure), cardiac valve insufficiency (leaking) or stenosis (narrowing), and exposure to toxins (alcohol or some cancer treatments).

When heart failure occurs, the ability of the heart to contract is decreased (systolic dysfunction), or the heart becomes stiff and does not relax normally (diastolic dysfunction); in some cases both conditions exist together. With less blood ejected from the heart at each beat, the body attempts to compensate for the decreased circulation to peripheral organs. Perhaps the most important response is the retention of salt and water by the kidneys in an attempt to increase intracardiac pressures and improve circulatory volume. As a result of these reflex actions, patients with heart failure usually show signs of congestion, along with weight gain and swelling of the extremities and abdominal organs—a condition known as congestive heart failure. Patients with congestion in the lungs or chest cavity suffer from short-windedness, particularly with exertion or while trying to lie flat. The heart's response to the systemic effects of circulatory failure is to enlarge the chambers (cardiomegaly) and increase the muscle mass (hypertrophy).

Treatment of heart failure is complex and multifaceted. Of prime importance is treatment of the specific underlying disease (such as hypertension, valvular heart disease, or coronary heart disease). Prescribed medications are usually aimed at blocking the adverse effects of the various neurologic, hormonal, and inflammatory systems activated by heart failure. These are generally drugs in the class of angiotensin-converting enzyme (ACE) inhibitors to lower blood pressure and decrease the heart's workload, beta-adrenergic blockers (beta-blockers (beta-blocker)) to stabilize the heartbeat, aldosterone antagonists to decrease salt retention, and vasodilators to relax the smooth-muscle lining of the veins and arteries. Diuretics (diuretic) are prescribed to remove excess fluid. Digoxin and digitoxin are commonly prescribed to increase the strength of heart contraction. (These latter drugs evolved from digitalis, which was introduced in the 18th century as one of the first effective remedies for congestive heart failure, known at the time as “dropsy.”) Patients are also advised to limit their intake of salt and fluids, avoid alcohol and nicotine, optimize their body weight, and engage in aerobic exercise as much as possible. Much can be done to prevent and treat heart failure, but ultimately the prognosis depends on the underlying disease causing the difficulty as well as the severity of the condition at the time of presentation.