Heart failure (sometimes known as congestive heart failure [CHF]) is a serious condition in which the heart is not pumping well enough. In late stages, the heart is unable to meet the body’s demand for oxygen. Heart failure is so named because the heart is failing to pump efficiently, which often results in congestion in the lungs. As a result, the heart tries to overcompensate for the problem, which only makes the problem worse.

Conditions that could lead to heart failure include the following:

• Coronary artery disease
• High blood pressure (hypertension)
• Heart attack
• Diabetes mellitus
• Cardiomyopathy
• Valvular heart disease (e.g., valvular stenosis or valvular regurgitation)
• Infection in the heart valves (valvular endocarditis) or of the heart muscle (myocarditis)
• Congenital heart disease (cardiac conditions present since birth)
• Severe lung disease (e.g., pulmonary hypertension) or obstructive sleep apnea
• Pericardial disease (pericarditis)

What is heart failure?
Heart failure is a serious condition in which the heart is not pumping well enough. In late stages, the heart is unable to meet the body’s demand for oxygen. Like a traffic jam, this can lead to congestion within the lungs as blood flows backward from the heart. Once this congestion begins, the patient may experience shortness of breath (dyspnea) that initially occurs only during exercise, and later even while at rest.

Contrary to its name, heart failure does not necessarily indicate that the heart has completely failed/stopped, which is the case when someone has gone into cardiac arrest. It means that the heart is operating at a decreased efficiency level and, therefore, is working harder to try and make up for the shortcoming in function. For example, the heart may pump more frequently to compensate for its weakened pumping ability. The longer the heart overworks itself to compensate for its shortcomings, the more its pumping ability is damaged and the more likely that serious pumping failure will result.

The increased workload of the heart may lead to changes in various parts of the body, as they try to compensate for the heart’s weakened ability to function. These changes can include the following:

   

• Remodeling. A significant physical change known as remodeling occurs with heart failure. Remodeling is most notably characterized by enlargement of the heart’s left ventricle. In addition, the left ventricle becomes thinner. There is an increased use of oxygen, greater degree of mitral valve regurgitation, and decreased ejection fraction. The process is a complex one. Contributing factors include the release of hormones in response to inflammation brought on by heart failure, or the extent to which a person's genes determine how the heart adapts after it is injured or diseased. Whatever the causes, left ventricular remodeling sets in motion an unhealthy domino effect, as progressive damage to heart cells leads to reduced cardiac output and more severe heart disease. This weakening may be “global,” as in cardiomyopathy, or regional, affecting only part of the left ventricle (e.g., heart attack).
• Hypertrophy of the heart walls. The heart walls may thicken in an attempt to strengthen their pumping ability.
• Tachycardia. An abnormally fast heartbeat that could result from the heart’s attempt to function more efficiently.
• Kidney malfunction. Initially, the kidneys respond to the heart’s low volume output by retaining water and salt. The kidneys perceive a low volume state, as if the person is dehydrated, and respond in kind. Unfortunately, the kidney’s response actually worsens the fluid buildup, and can contribute to high blood pressure. This places added stress on the filters in the kidneys (nephrons), and is a major cause of kidney failure.
  

Which conditions could lead to heart failure?
There are a variety of conditions that could lead, or are associated with, heart failure. These conditions include the following:

• Coronary artery disease (CAD). One of the most common causes of heart failure. CAD is a chronic disease in which there is a “hardening” (atherosclerosis) of the arteries on the surface of the heart. The term “hardening” refers to a condition that causes the arteries to become so narrowed and stiff that they block the free flow of blood. Severely reduced blood flow to the heart may weaken s the heart muscle. In this situation, restoration of blood flow (Coronary artery bypass or Balloon angioplasty)
• Arrhythmia. A serious arrhythmia can diminish the effectiveness of the heart's pumping ability.
• Heart attack (myocardial infarction). Following a heart attack, part of the heart muscle is replaced with scar tissue that prevents the heart from working efficiently. As the weakened heart muscle struggles to pump blood, the muscle fibers of the heart stretch, resulting in enlarged and weakened chambers in the heart (remodeling). The AHA estimates that about 22 percent of patients who suffer a heart attack will become disabled with heart failure within six years.
• High blood pressure (hypertension). High blood pressure has been called the single most common risk factor for the development of heart failure. Nearly 75 percent of all heart failure cases involve patients with previously diagnosed hypertension. Uncontrolled high blood pressure causes the heart muscle to overwork itself in order to pump blood under high pressure throughout the body. Untreated, hypertension will cause the heart to overwork itself to the point where serious complications such as heart failure could result. Increases in blood pressure are associated with a greater incidence of heart attack.
• Cardiomyopathy. A type of chronic heart disease in which the heart muscle becomes abnormally enlarged, thickened and/or stiffened. As a result, the heart muscle’s ability to pump blood can become increasingly weakened. This condition is often seen with viral infections or alcohol abuse, but in many patients the cause is never found.
• Valvular heart disease. Narrowing (stenosis) or leaking (regurgitation) of one or more of the heart’s four valves. The resulting restriction in blood flow in stenosis, or overload of blood in regurgitation, can lead to heart failure. These patients are initially treated with medication, but will often require valve surgery. There may also be an infection in the heart valves (valvular endocarditis). Valvular disease is most often a result of the aging process, but may also be a type of congenital heart disease (present from birth). Less commonly, it results from rheumatic heart disease.
• Congenital heart disease. A heart-related problem that is present from birth. It involves one or more defects in the heart (e.g., ventricular septal defect, atrial septal defect), the veins leading to the heart, the arteries leaving the heart or connections among these various parts of the body.
• Severe lung disease (e.g., pulmonary hypertension). When the right side of the heart cannot generate enough force to pump blood through a diseased pair of lungs, congestive heart failure can result.
• Diabetes mellitus. This is a strong risk factor for developing coronary artery disease or heart attack, which may lead to heart failure and also cardiomyopathy.
• Obstructive sleep apnea (OSA). A condition commonly found among individuals with congestive heart failure. Muscles in the back of the throat normally work to keep the throat open, but the airway can become blocked if the muscles relax during sleep. When the brain detects a drop in oxygen from not breathing, it quickly sends a signal to the chest muscles and diaphragm to gulp in air. As a result, the sleeper makes a gasping or snorting sound and is awakened. This struggle to breathe and arousal from sleep causes tension in the left ventricle and increases in heart rate, blood pressure, and the body's demand for oxygen. This increases the risk for developing ischemia, arrhythmia, chronic high blood pressure, pulmonary hypertension and carotid artery disease. Treatment includes continuous positive airflow pressure (CPAP), in which a bedside machine delivers air continuously through a plastic mask over the nose. The predetermined air pressure acts as a splint to keep the airway open, while still allowing the person to exhale. CPAP has shown to be effective in lowering blood pressure and increasing ejection fraction, suggesting that the relief of obstructive sleep apnea can also impact on symptoms of heart failure.
• Anemia. Anemia is a deficiency in red blood cells and/or hemoglobin, the iron-rich, oxygen-carrying molecules in red blood cells. Chronic, severe anemia can be a cause of congestive heart failure, and can worsen as heart failure progresses. Even mild to moderate anemia is a common finding in patients with congestive heart failure. This is because the heart must work harder in order to circulate a decreased number of red blood cells throughout the body. But recent studies have shown that correcting anemia could improve heart failure. Patients treated with a combination of intravenous (I.V) iron and injections of erythropoietin (a protein that increases red blood cell production) have exhibited an increased ejection fraction, decreased need for diuretics.

There also appears to be a link between clinical depression and cardiovascular health. Clinical depression is diagnosed in 15 to 20 percent of heart patients with no history of heart attack, and up to 65 percent of heart patients who have had a heart attack.

Not only can clinical depression increase the likelihood of developing or dying from a heart problem, but also a heart problem can increase the likelihood of clinical depression. It is felt that clinical depression triggers higher levels of stress hormones (e.g., adrenaline) in people with depression than in those without. This may help to explain why the hearts of clinically depressed people beat faster, even during sleep. It is also consistent with earlier findings that people with both heart disease and clinical depression have reduced heart rate variability (the heart’s ability to handle stress).

Other conditions that may lead to heart failure include lupus, rheumatoid arthritis, hyperthyroidism, certain chemotherapy drugs, alcohol abuse and abuse of some types of drugs (primarily amphetamines and cocaine).

The risk of developing heart failure is also increased by the presence of certain risk factors, which include the following:

• Smoking
• Obesity (more than 20 percent over one’s ideal weight)
• Lack of exercise
• Dietary habits, such as high salt intake or the failure to take medication properly
• Uncontrolled hypertension
• Arrhythmias
• Worsening lung disease (emphysema) or pulmonary embolism
• Infection
• Emotional distress
• Certain medications
• Fluid overload
• Hyper- or hypothyroidism

What are the different types of heart failure?
There are a number of different types of heart failure, which are classified according to which side of the heart is more affected, which phase of the heartbeat is more affected and how severe the condition is.

Two types of heart failure are identified according to which side of the heart is most affected:

• Left-sided heart failure occurs when the left ventricle cannot adequately pump oxygen-rich blood from the heart to the rest of the body. The main symptoms for this condition include shortness of breath, fatigue and coughing, especially at night and/or while lying down. There may also be lung congestion (with both blood and fluid).
• Right-sided heart failure (cor pulmonale) takes place when the right ventricle is not pumping adequately, which tends to cause fluid build-up in the veins and swelling (edema) in the legs and ankles. Right-sided heart failure usually occurs as a direct result of left-sided heart failure. It can also be caused by severe lung disease (e.g., chronic obstructive pulmonary disease, pulmonary hypertension) in which the right side of the heart cannot generate enough force to pump blood through a diseased pair of lungs.

Another two types of heart failure are identified according to which phase of the heart’s pumping cycle is more affected:

• Systolic heart failure means that the heart is unable to pump out adequate amounts of blood during its contraction (systole). Lung congestion and swelling (edema) of the lower extremities are typical symptoms of systolic heart failure.
• Diastolic heart failure refers to the heart’s inability to relax between contractions (diastole) and allow enough blood to enter the ventricles. Symptoms are identical to systolic heart failure. Diastolic heart failure is often a precursor to systolic heart failure. Patients with diastolic heart failure may or may not have normal systolic function.

Heart failure tends to get progressively worse over time. Four levels of heart failure, each more serious than the one before it. These levels are as follows (with approximate percentage of patients):

• Class I: No obvious symptoms, no limitations on patient physical activity (35 percent of heart failure patients).
• Class II: Some symptoms during or after normal activity, mild physical activity limitations (35 percent of heart failure patients).
• Class III: Symptoms with mild exertion, moderate to significant physical activity limitations (25 percent of heart failure patients).
• Class IV: Significant symptoms at rest, severe to total physical activity limitations (5 percent of heart failure patients).

Aggressive treatment of high blood pressure, diabetes mellitus and coronary artery disease could prevent development of symptomatic heart failure. The AHA/ACC stages are:

• Stage A: The patient at high risk for heart failure, but has no heart abnormalities.
• Stage B: The patient has structural abnormalities of the heart, but no symptoms.
• Stage C: The patient has past or present symptoms associated with heart disease.
• Stage D: The patient has end-stage disease, requiring specialized treatment (e.g., continuous intravenous (IV) drug therapy, left ventricular assist device, heart transplant).
  
  

• Shortness of breath (dyspnea). This is one of the earliest symptoms of heart failure. The patient gets winded and fatigued more quickly than before, just by doing regular daily activities or even lying in bed. There is also decreased tolerance to exercise, and the muscles may feel weaker than before.
• Swelling (edema) of the legs is another common symptom in heart failure, though it could also be caused by unrelated conditions.
• Swollen neck veins.
• Abdominal discomfort such as swelling, pain or nausea.
• Mental confusion.
• Galloping heartbeat (palpitations).
• Kidney malfunction or failure (in the later stages of heart failure).

In addition to the symptoms listed above, which the patient may notice, the physician may also be able to detect signs of congestive heart failure, which include the following:

• An abnormal heart murmur (a telltale sign of a valve-related disorder).
• A crackling sound of fluid in the lungs (rales), which is a sign of pulmonary congestion.
• A rapid heartbeat (tachycardia) or abnormal heart rhythm (arrhythmias).
• Swelling and fluid retention (edema) in the liver or gastrointestinal tract (in advanced stages of heart failure).
• Hypertrophy or enlargement of the heart. '
• Liver malfunction.

• Blood tests. Traditional tests evaluate potential causes of heart failure, such as anemia and thyroid function, and electrolytes and kidney function. However, a new test may be effective in diagnosing heart failure. The blood test measures levels of B-type natriuretic peptide (BNP), a protein that is produced by the heart as it fails.
• Echocardiogram of the heart and major arteries. This test uses ultrasound technology to closely examine the overall muscle function of the heart, allowing the physician to evaluate the size, thickness and pumping action of the heart, and how well the heart valves are functioning. A stress echocardiogram may also be useful in assessing how well the heart is functioning at rest and during exercise. An echocardiogram is the single most important test for the diagnosis of heart failure.
• Electrocardiogram (EKG). A test that measures the heart’s electrical activity. It is designed to detect any abnormal heart rhythms, heart enlargement, cardiac ischemia or heart attack.
• Exercise stress test. A test in which an EKG is performed at rest and then under the physical stress of exercise, to compare the heart's performance at rest and during times of physical exertion.
• Radionuclide imaging tests, such as a radionuclide stress test or ventriculogram. These provide contrast images of the heart, which can pinpoint areas of damage and/or dysfunction and determine how well the heart is pumping.
• Chest roentgenography (x-ray) to evaluate the size and shape of the heart, as well as to view the lungs and any fluid that may have built up.

More invasive exploratory tests may be ordered in conjunction with, or instead of the above. These tests include a coronary angiogram, in which a contrast dye is delivered by catheter to the coronary arteries to visualize the blood vessels and identify heart damage or dysfunction

• Limiting physical activity until approved by one’s physician, and then staying as active as possible. Heart failure patients who exercise regularly typically show significant improvement, whereas heart failure patients who were inactive showed a clear decline. Heart failure patients should consult their physician before beginning an exercise program.
• Scheduling relaxation and rest periods throughout the day.
• Avoiding excessive fluid intake.
• Keeping a diary of one’s daily weight, and notifying one’s physician if there is a weight gain of three or more pounds in a single week (which may indicate fluid retention and the need for an immediate change in treatment).

Patients with heart failure should always consult their physician before taking any over-the-counter medicines, vitamins or herbal supplements.

Depending upon the nature of the underlying damage or malfunction that leads to heart failure, medications may be prescribed to reduce the heart’s workload, affect remodeling, counter abnormal hormonal levels, increase blood flow, widen vessels or eliminate excess water from the body. Medications used to treat heart failure and related conditions include the following:

• ACE inhibitors. A type of vasodilator that expands blood vessels to allow blood to flow easier and more freely, allowing the heart to pump more efficiently. ACE inhibitors act by preventing the production of a chemical that causes blood vessels to tighten and narrow. ACE inhibitors lower blood pressure so that the heart does not have to work as hard to pump blood. Reports from the National Institutes of Health indicate that the use of ACE inhibitors has been the most significant factor in heart failure survival rate improvement over recent years. They also have a favorable impact on the heart itself (e.g., affecting remodeling).
• Angiotensin II receptor blockers may also be used in conjunction with ACE inhibitors. They can also be used in patients who cannot take ACE inhibitors or beta blockers.
• Beta blockers. May prevent progression of the disease and improve symptoms by slowing the heart's contraction rate and reducing its pumping action, thus lessening the heart’s workload. For many years beta blockers were considered inappropriate for people with heart failure because they can potentially weaken the heart muscle and cannot be used when the patient’s health is unstable. Recent studies have shown that selected beta blockers may be very helpful in treating heart failure. They have been shown to decrease mortality and improve left ventricular function in these patients. Beta blockers also reduce the likelihood that these patients will suffer from significant rhythm problems of the heart.
• Diuretics. Often referred to as water pills, these reduce the symptoms of congestion by helping to flush away excess salt and fluids from the body. They are very useful in treating people with heart failure and fluid retention. Spironolactone, a “potassium-sparing” diuretic, has been found to be effective therapy in patients with severe heart failure.
• Digoxin. Helps the heart to contract more vigorously and effectively, and helps to reduce the symptoms of heart failure. It is most often used to control the fast heart rate of atrial fibrillation. It may be ineffective in women with heart failure and abnormal rhythm.
• Inotropes. Intravenous drugs that increase the force of the heart's contractions, allowing the heart to beat less frequently and more effectively. Individuals with severe heart failure often benefit from being hospitalized and being given these powerful medicines intravenously for 24 to 48 hours.

• Balloon angioplasty. A catheter-based procedure in which plaque is pressed back against artery walls to make more room for blood to flow through the artery.
  
• Coronary stenting. The insertion of a wire mesh metal tube called a stent into a clogged vessel in order to help keep it open.

• Coronary artery bypass surgery, for patients with severe or total artery blockage.
• Heart valve surgery, in patients with severe valvular regurgitation or valvular stenosis
• Pacemaker insertion to correct the slow heart rhythm (bradycardia) that can worsen heart failure.
• Cardiac resynchronization (e.g., biventricular pacemaker)
• Aneurysm surgery in selected patients.
• Heart transplant surgery, in the most severe cases.
• Insertion of a left ventricular assist device prior to transplant surgery.
• Implantable cardioverter defibrillator (ICD): though not used to treat heart failure per se, many heart failure patients are at risk for life threatening (arrhythmias).

• Total artifical heart. The Food and Drug Administration (FDA) approved clinical trials for a fully implantable total artificial heart. The grapefruit-sized device is powered by a battery that can be recharged from outside the body without the need for tubes to remain connected through the skin. Subjects of the study are end-stage heart failure patients who are not eligible for a heart transplant, cannot be helped by other available therapies and are at imminent risk of death. Initial results have been poor.
• Vascular endothelial growth factor (VEGF). A form of therapeutic angiogenesis currently being studied in a trial named VIVA (VEGF for Ischemia in Vascular Angiogenesis). Two methods of administering VEGF are being explored. The first method is to inject a protein that commands tissue to produce VEGF directly into the heart. The heart muscle then begins producing its own VEGF. The second method is to deliver the actual VEGF protein by direct infusion into the heart or through intravenous (IV) injection. The second method has begun testing in human patients. Early results have been promising.
• Heart jacket. A synthetic, elastic material that is surgically attached and wrapped around the heart surface. The mesh-like fabric supports the ventricles (the heart's lower chambers), providing a snug fit but without constricting the heart. The goal is to reverse remodeling of the left ventricle (see What is heart failure?). Remodeling was assumed to be irreversible. But recent successes with beta blockers and ventricular assist devices show that remodeling can be improved. In earlier animal and now human studies, the heart jacket support device demonstrated that it does more than keep the left ventricle from enlarging. It can actually reshape and restore it to a more normal form. This led to a significant decrease in the process of self-destruction of heart muscle cells - another hallmark of heart failure. There was a rise in cardiac output as well as improved ejection fraction. Even with the success of the device so far, it is expected that patients receiving heart jackets would continue their medications (e.g., beta blockers).
• Heart valve repair. When a heart becomes enlarged it often prevents the heart's valves from properly closing, allowing blood to leak back in the wrong direction (regurgitation). Certain heart valve surgeries can implant an annuloplasty ring to restore the normal dimensions of the valve, allowing it to come together properly. While these surgeries are common as treatments for valvular heart disease, they are still considered experimental for treating heart failure. The University of Michigan is currently planning a research project that will compare the outcomes of valvular surgery for heart failure patients with more traditional medication-based methods of treatment.