What is heart failure?

Congestive heart failure, often known simply as heart failure, is a condition in which your heart is unable to pump enough blood around your body. The heart cannot work as well if there has been damage to the heart tissue, including weakened or stiffened heart muscle. This can occur from scarring due to heart attacks, high blood pressure, and faulty heart valves.

If your heart is struggling to work, you may feel tired and fatigued. You may also feel a shortness of breath or notice your legs and ankles swelling up. This is due to blood 'damming up' or congesting within the heart and vessels, eventually causing fluid to leak into and collect within your lungs or other body tissue.


The heart is comprised of four chambers that form two pumps. Each of the pumps include an upper atrium and a lower ventricle. The right atrium receives deoxygenated (low oxygen) blood from the veins, then 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, either or both ventricles do not completely empty of blood. The backlog of blood in the heart can trigger fluid retention in the lungs, causing breathlessness, or fluid retention in the veins, causing swelling particularly in the legs and abdominal organs.

Healthy heart muscle has a normal blood flow (solid lines). Weakened or stiffened heart muscle has a decreased blood flow (dashed lines). 

Heart failure can be caused by numerous underlying medical conditions:

Coronary artery disease

Coronary artery disease is caused by fatty deposits (known as atherosclerosis) clogging up arteries that supply blood to your heart. This causes blood flow to slow down through these narrowed arteries and deliver less oxygenated blood to certain parts of your heart. This eventually damages the heart tissue, which predisposes to heart failure.

Heart attack

A heart attack is caused by a sudden stoppage of blood flow to your heart when a clot blocks one or more of your coronary arteries. If the artery is not unblocked quickly, heart muscle is irreversibly damaged, which can lead to heart failure.


Hypertension is also known as high blood pressure. Hypertension is a common condition in which there is increased pressure of your blood against the inner walls of your arteries while it is pumped by your heart. Over time your heart must work harder to pump blood around your body. This can cause your heart muscle to compensate for this extra workload by becoming thicker. Eventually, the heart muscle may not be able to properly pump blood, as it has become too thick or weak.

Faulty heart valves

The flow of blood in your heart is controlled by the heart valves. Heart valves can become faulty due to age, infections or coronary artery disease. A faulty heart valve places extra pressure on the heart to pump sufficient blood to the rest of the body. Over time, your heart can become weakened by this extra work.


Cardiomyopathy is a condition where the heart muscle becomes inflamed and enlarged, usually due to genetic causes. The enlargement of the heart reduces its ability to effectively pump blood around the body.


This is a condition in which a virus or other infection has damaged the cardiac muscle.

Congenital heart defects

These are heart defects that you are born with. Defects can include valves or chambers that are not formed correctly and therefore make your heart work harder. This can eventually lead to heart failure.

Heart arrhythmias

An arrhythmia is an abnormal heart rhythm. This can cause the heart to beat faster than it should, making extra work for the heart and weakening it over time. An abnormally slow heartbeat can also lead to heart failure if it cannot circulate enough blood around the body.


Hyperthyroidism is a thyroid disease characterized by overproduction of the hormone thyroxine by the thyroid gland. This can increase the heart's work and potentially lead to heart failure.

In addition to the specific causes of heart failure, some medical conditions that can contribute to heart failure include:

Amyloid disease

A condition in which abnormal proteins accumulate in organs and tissues of the body, including the tongue, intestines, heart, skin, liver, kidneys and brain.


A deficiency in red blood cells or hemoglobin in the body.


A metabolic disorder that is caused by problems with insulin secretion and regulation and which is characterized by high blood sugar levels. Also known as diabetes mellitus.


A long-term, progressive condition in which the air sacs in the lungs are damaged. This causes breathlessness, as the lungs cannot adequately exchange gases across membranes.

Coronary arteries

An artery that supplies blood to the heart muscle.


The thickened or solid mass formed from a liquid, such as blood. Blood clots normally form at an injury site to prevent further blood loss.


There are many different ways in which heart failure can be grouped. The more common of these include:

Right and left heart failure

This is based on whether the right or left side of the heart is not pumping adequately. If the left ventricle is not working adequately, this can cause the build-up of fluid in the lungs leading to breathlessness. Right-sided heart failure is usually the result of left heart failure or chronic lung conditions, and can cause swelling in your abdomen, legs and feet.

Systolic and diastolic heart failure

Systolic heart failure occurs when the left ventricle can no longer contract properly. This leaves the heart without enough force to pump blood around the body. Diastolic heart failure occurs when cardiac muscle becomes too stiff and are unable to relax normally. During this condition, the heart is unable to fill correctly in between heartbeats. The symptoms of diastolic and systolic heart failure are very similar.

Chronic and acute heart failure

Many people with heart failure can develop symptoms gradually and will require long-term treatment for their condition. This is chronic heart failure. Acute heart failure occurs after an event that effects the heart and causes a rapid decline in heart function, such as a heart attack.

Signs and symptoms

The main symptom of heart failure is shortness of breath. It commonly occurs when lying down flat and characteristically causes individuals to wake up in the middle of the night gasping for air. Other signs and symptoms can include:

  • Tiredness or lethargy;
  • Muscular fatigue;
  • Unexplained coughing and wheezing;
  • Nausea or loss of appetite;
  • Swelling of the ankles, legs and stomach;
  • Dizziness;
  • Weight gain from fluid retention, and;
  • Chest pain.

Methods for diagnosis

Heart failure is usually diagnosed with a physical exam and a number of tests. These include:

Blood tests

There is a specific blood marker, called brain natriuretic peptide (BNP), which can be performed to help confirm the diagnosis, assess severity and monitor response to treatment. Several other blood tests can also be performed to identify the underlying cause for the heart failure. These include full blood count, cardiac enzyme tests and thyroid hormone tests.

Chest X-ray

A chest X-ray can show whether the cardiac muscle is enlarged, or if there is fluid build-up caused by heart failure.


Echocardiography uses ultrasound waves to create an image of the heart. It allows your doctor to see the size of your heart and also how well it's working. It can show how hard your heart is pumping blood, whether it's leaking and highlight areas of damage.

Electrocardiogram (ECG)

Electrocardiography uses electrodes attached to your chest and limbs to check your heart rhythm. The beat of your heart is caused by coordinated electrical currents through its cells. During an electrocardiogram, electrodes are attached to your chest while you lie on your back. These record your heart's electrical activity from different angles. This test is used to determine if there are any abnormalities in your heart rhythm.

A person with electrodes on their chest undergoing an electrocardiogram.An electrocardiogram procedure. 

Some other tests that may be performed include:

Myocardial perfusion imaging (MPI)

This is a nuclear medicine test that uses substances such as thallium or sestamibi, to view how well the muscles of the heart are working and how the blood is getting to these muscles.


Angiography involves a thin catheter inserted into one of your major arteries through your arm or leg, to check for blockages in your arteries. Once the catheter is inserted, a dye is administered and X-rays taken to visualize the coronary arteries, and any narrowing or blockages that are present.


A thin, flexible tube inserted through a narrow opening into a body cavity for removing fluid.


An injectable drug containing a radioactive element used in nuclear medicine.


A metallic element used in nuclear medicine.

Coronary arteries

An artery that supplies blood to the heart muscle.

Types of treatment

Currently there isn't a cure for heart failure, but there are treatments that may help you to manage your condition while living a fulfilling life. A main focus of treatment is to identify and treat any underlying condition that has caused heart failure, e.g., hypertension. This will help prevent your condition from getting worse. Some treatments can include:

Lifestyle changes

Some lifestyle changes include regular light physical activity, reducing excess body fat, quitting smoking, adopting a healthy diet that is low in fat and salt, limiting alcohol and getting adequate rest. As heart failure advances, your doctor may recommend a maximum daily limit on the fluids you have. This is to help control the build-up of fluid in the body. Most people with heart failure will also be told to regularly monitor their body weight. This can easily identify changes in the body's fluid levels, and help guide treatment in terms of increasing or reducing medications.


To treat heart failure, a combination of medications may be required. Depending on your symptoms, some medications can include:


Diuretics remove excess fluid from your body by making you urinate more often. Diuretics can also reduce the fluid on your lungs to help you breathe easier. Sometimes, diuretics can also cause your body to lose natural minerals including magnesium and potassium, so your doctor may monitor the levels of these in your blood and prescribe supplements of these minerals if needed. A commonly used diuretic is frusemide. Another diuretic called spironolactone, is also commonly used as it has been shown to improve survival in those with severe symptoms and systolic heart failure. Usually, the dose of diuretics is adjusted to changes in daily body weights.

Angiotensin-converting enzyme (ACE) inhibitors.

ACE inhibitors are vasodilators that can reduce blood pressure by opening blood vessels. This can ease the strain on the heart and lead to a reduction in salt and water retention in your body. Some examples include enalapril, lisinopril and captopril.


Beta-blockers work by slowing your heart rate and reducing your blood pressure. Some examples include carvedilol, metoprolol and bisoprolol.


Digoxin, also known as digitalis, helps your heart to pump more effectively by increasing the strength of your heart muscle contractions. Digoxin also tends to slow the heart rate down.

Additional medications

Along with your heart failure medication, your doctor might also prescribe other medications. These can include statins (cholesterol-lowering medication) if required, nitrates for chest pain, or blood-thinning medications to prevent the formation of blood clots.

Surgery and medical devices

In more serious cases of heart failure, surgery or medical devices may be needed. These can include:

Replacement or repair of heart valves

If your heart failure involves a faulty heart valve, your doctor might recommend it be repaired or replaced.

Coronary bypass surgery

Also known as a coronary artery bypass graft, this can be performed if you have severely blocked arteries. To help blood flow through your heart more freely, a blood vessel is taken from your chest, arm or leg and used to bypass the blocked artery in the heart.

Heart transplant

In some cases, when other treatments are not successful, you may require a donor heart.

Left ventricular assist devices (LVADs)

These are heart pumps that are surgically inserted and attached to a damaged heart. They are powered by external battery packs and can be used as a substitute while you are waiting for a donor heart to become available.


Substances that hinder the activity of hormones such as adrenaline by blocking the beta receptors, found in many organs but particularly the heart and blood vessels. These are used to treat a range of conditions including high blood pressure and migraines.


A type of fat produced by the body that is necessary for metabolism.


Chemical compounds containing a particular chemical group made up of one nitrogen atom and three oxygen atoms. These can be used to dilate blood vessels and also as preservatives in food.


A water-soluble compound and major mineral that is essential for maintaining contractions of muscles, including the heart.


An important mineral that is essential for the development of bones and teeth, energy production and muscle contraction.


Some complications associated with heart failure include:


A stroke is damage to the brain from either blockage of blood flow or bleeding into the brain. During heart failure, blood may travel more slowly through the heart. This can lead to the formation of clots and increase your risk of having a stroke.

Kidney failure

A reduction in blood flow can cause your kidneys to fail (chronic renal failure) if it is not treated. You may require dialysis if you suffer kidney damage.

Liver damage

During right heart failure, the liver can become congested with blood, placing it under pressure, which can cause scarring and eventually lead to a decrease in function.


Heart failure is a potentially serious and life-threatening condition. However, in most cases, symptoms can subside and heart function can improve with correct treatment. It is important to have regular monitoring and adhere to treatments, including lifestyle changes and medications, to lead a good quality of life.


To help prevent heart failure, it is important to live a healthy lifestyle and reduce your risk of conditions that cause heart failure. Two main conditions to avoid are coronary artery disease and hypertension.

If you are diagnosed with heart failure and want to prevent the condition from getting worse, you may want to:

  • Monitor your fluid intake and retention;
  • Limit your salt intake;
  • Quit smoking, and;
  • Restrict your alcohol intake.

FAQ Frequently asked questions