The human heart is a muscular pump that keeps blood flowing around the body. It accepts blood from the organs and tissues and pumps it to the lungs to be enriched with oxygen. The blood rich in oxygen is returned to the heart and is then pumped to the tissues of the body to supply them with oxygen. Blood filled with carbon dioxide and waste products are circulated away from the tissues to be cleaned.

Diseases of the heart and blood vessels

The human heart will beat about 3 billion times from birth to the age of 90 years. Along the way many things can go wrong with the human heart, including with the heart muscle itself, with the valves that help blood flow, with the heart rhythm, and with the blood vessels that transport the blood.

The heart cannot function at its best without a healthy network of blood vessels that carry the blood away from the heart and back to the heart again. These blood vessels that carry blood are called arteries and veins. Diseases of the heart itself and the blood vessels are together referred to as cardiovascular diseases (CVD).

Heart diseases can be caused by genetic factors, lifestyle choices, birth defects, infections, or a combination of factors. Read more about the risk factors for heart disease



Venous thromboembolism is a blood clot formed in a vein and can travel in the network of blood vessels until it blocks a blood vessel. Deep vein thrombosis occurs when a blood clot blocks a vein, typically in the leg. Pulmonary embolism occurs when a blood clot travels to the lungs and blocks the blood supply to a part of the lungs.

Blood clots can be triggered by medical procedures or by other medical conditions, or by periods of immobilization such as lying in a hospital bed or a long flight. Blood can also clot easier in certain medical conditions such as cancer and autoimmune disorders, with medical treatments, with hormone therapy, due to inherited conditions, and with increasing age.

Watch a visual explanation of Venous thromboembolism from the American Heart Association

Peripheral artery disease is a narrowing of the arteries that transport blood to the legs, stomach, arms, and brain. Similar to what happens with ischemic heart disease, atherosclerosis cause gradual build-up of plaque in these arteries.

Peripheral artery disease often occurs in the legs where the blood flow and therefore the nutrient and oxygen supply to the large leg muscles are restricted. This can cause pain, cramping and weakness in the legs, especially when the leg muscles are engaging in exercise.

As peripheral artery disease worsens it can cause more serious damage such as gangrene and amputations. Similar to atherosclerosis that affects the coronary arteries, peripheral artery disease can be prevented and improved by healthy living.

Cardiomyopathy refers to a collection of diseases that affect the normal functioning of the heart muscle itself. The heart muscle can become abnormally enlarged, too rigid and weakened. It can lead to heart failure, an abnormal heart rhythm or in some cases cardiac arrest.

There are many types and causes for cardiomyopathy, from inherited disorders to cardiac myopathy caused by other illnesses or lifestyle factors. The severity of the disease and the treatment options depends on the type of cardiomyopathy.

Angina is a symptom usually caused through coronary artery disease. Angina is chest pain or discomfort which occurs when not enough blood flows for the heart muscle to function effectively. The cause is usually narrowing of the coronary arteries, but in an angina attack heart muscle damage does not result.

The pain is usually felt in the centre of the chest and may spread to the arms, neck, jaw, and or back. It is usually a constricting pain or tightness which may restrict breathing. Sharp stabbing pains on the left side of the chest are not due to heart disease.

Stable angina is triggered by exertion, such as exercise, which increases the work rate of the heart thus leading to a greater demand for oxygen by the heart muscle. Resting or prescription medication usually reverses these symptoms.

Unstable angina happens at rest and can become progressively worse. If you regularly suffer angina but you think it is getting worse or more frequent you should contact your doctor.

If you have never had angina before and experience chest pain you should follow the advice for a possible heart attack

Watch a visual explanation of angina from the American Heart Association

Atherosclerosis is the build-up of fatty material and other substances inside your arteries. It’s the underlying condition that causes most heart attacks and strokes.

The build-up occurs under the thin inside lining of the blood vessel and is called a plaque or atheroma. The plaque can harden the blood vessels and narrow the blood vessel to restrict blood flow.

The plaque can also break open which will trigger the formation of a blood clot. Such a blood clot can block the artery and completely stop blood flow. Atherosclerosis inside arteries happens gradually over decades. The more build-up there inside the arteries, the greater the risk of future heart disease or strokes. Atherosclerosis typically has no symptoms until it becomes very severe or causes a heart attack or stroke. Atherosclerosis can be largely prevented and improved by a healthy lifestyle.

Watch a visual explanation of atherosclerosis from the American Heart Association

There are four chambers in the heart and during the rhythmical contraction of the heart the blood is pushed between the cambers from between a camber and a large blood vessel entering or leaving the heart. Heart valves are important to separate the blood in different chambers, and the direct the flow of blood in the right direction.

The heart valves can be damaged or start to work poorly, and this effect the functioning of the heart. Over time this can cause heart failure or increase the risk for other conditions.

Abnormal heart valve function can be caused by inherited abnormalities or birth defects, by rheumatic fever, by infections, by cardiomyopathy, or by damage to the heart after a heart attack.

Watch a visual explanation of the function of normal and abnormal heart valves from the American Heart Association

Kawasaki disease, also known as Kawasaki syndrome, is a serious illness characterized by inflammation of blood vessels throughout the body that primarily affects young children and infants. Kawasaki disease is a leading cause of acquired heart disease in children. Although about 80 percent of patients are under five years of age, older children and teenagers can also get Kawasaki disease, but this is uncommon. KD is more common in boys than girls. It is not contagious.

The cause of KD is unknown, although an agent, like a virus, is suspected. Kawasaki Disease is characterized by an inflammation of the blood vessels throughout the body. There is no specific test for Kawasaki disease; doctors make a clinical diagnosis based on a collection of symptoms and physical findings. Early symptoms of Kawasaki disease include high fever that lasts at least 5 days, red lips, red eyes, strawberry-red tongue, a bumpy rash, red palms and soles, swollen hands and feet, aching joints, swelling of the glands in the neck and a loss of appetite.

Any parent whose child has persistent fever and any of these symptoms should take him or her to the doctor immediately.

Without treatment, about 25% of children develop heart disease involving the coronary arteries. Timely diagnosis and treatment is highly effective in preventing complications.Read more about Kawasaki disease from the Kawasaki Disease Foundation

Rheumatic heart disease is a type of preventable heart disease that manly affects children and young adults, particularly those who live in poverty and overcrowding. The disease is not common in high income countries, but is still affects millions of people and causes hundreds of thousands of deaths annually, mainly in Africa, the Middle East, Central and South Asia.

Rheumatic heart disease occurs when attacks of acute rheumatic fever cause permanent scarring and damage to the valves of the heart. If left untreated, rheumatic heart disease can lead to stroke, heart failure, and death.

Acute rheumatic fever is an abnormal immune reaction to group A streptococcal bacterial infection. This common infection often occurs in the throat and may be known as strep throat. Symptoms of Acute Rheumatic Fever usually begin two or three weeks after a strep infection and can include symptoms such as joint pain, fever, feeling sick, a skin rash, uncontrollable movements or changes in mood. If a child shows any of these symptoms, particularly if they have a sore throat before the symptoms, they should be taken to the doctor.

Acute rheumatic fever can easily be prevented by treating a step throat infection with a common antibiotic. This infection can cause throat pain or pain on swallowing, Fever higher than 38°C and feeling unwell with headache, nausea, vomiting or weakness. Strep throat does not normally cause a running or blocked nose like a cold or a flu. Children should see a doctor or health worker whenever they have a sore throat.

Children of young adults who already have rheumatic fever need continued medical care. This may include antibiotics, blood thinners, regular medical appointments, and sometimes surgery. Girls and women with rheumatic heart disease are at a high risk of further health problems during pregnancy and labour. Many need to be on birth control and should discuss pregnancy with their doctor first.

Learn more about rheumatic heart disease from RHD action

Congenital heart defects occur when the heart or blood vessels near the heart develop abnormally before birth and the baby is born with them. Congenital heart defects affect the normal functions of the heart. Most heart defects either obstruct blood flow to or inside the heart, or cause blood to flow through the heart in an abnormal pattern. The defects range in severity from simple problems to severe malformations that can cause heart failure.

What causes heart defects?

In most cases the cause is not known. A heart defect forms during early pregnancy (between the 6th and 12th week) – very often before a mother realises that she is pregnant. Sometimes the cause can be identified. A mother may have an increased risk of having a baby with a heart defect if during pregnancy she: has a viral infection such as German measles, suffers from diabetes, conditions such as Down’s Syndrome, uses certain medications, abuses alcohol and “street” drugs. A family history also plays a role in congenital heart defects. It is, however, important to emphasise that the abnormality is not the fault of the parents.

What are the common signs and symptoms and what should parents look out for?

Critical congenital heart disease manifests in the first few hours/days of life and often presents with cyanosis or blueness, associated with a blue tongue or blue lips, fast heartbeat, fast breathing, cold hands and feet, and poor pulses to feel. Signs and symptoms in early infancy include poor weight gain, pale or bluish skin colour and especially concerning would be bluish tongues and lips. Fast breathing when sleeping, at rest or feeding is also a concern as is sweating profusely. In older children, signs include tiredness, getting out of breath easily and frequent colds and respiratory illnesses.

Often congenital heart disease is missed or diagnosed too late. Some babies born with a heart defect can appear healthy at first and only develop symptoms later. It is important to ask the sonographer whether your unborn baby’s heart is normal when you have a sonar scan.

Your child should also be tested for CHD before they leave the hospital by a simple test called pulse oximetry screening. Pulse oximetry screening is a simple, non-invasive test that determines the amount of oxygen in a baby’s blood and the baby’s pulse rate. Low levels of oxygen in the blood can be a sign of a CHD or other serious health problems.

Learn more about the different types of congenital heart disease from the Paediatric Cardiac Society of South Africa.

Arrhythmia (abnormal heart beat) includes tachycardia (fast beating heart), bradycardia (excessive slowing of the heart beat), palpitations (symptoms experienced by a racing or irregular heart beat).

Occasionally people become aware of their heart beating which may be a rapid, excessively slow, irregular or “skipped” beat. Not all these sensations are associated with heart disease. Other symptoms which may accompany palpitations are dizziness, light-headedness or a feeling of fainting.

Atrial fibrillation or AF is the most common sustained abnormal heart rhythm, or arrhythmia, worldwide. This dangerous arrhythmia causes the two upper chambers of the heart (the atria) to quiver instead of beating effectively, resulting in blood not being completely pumped out, which in turn causes pooling and can lead to clotting. These clots can travel to the brain, block an artery and interrupt the brain’s blood supply. This can trigger a major and often fatal stroke. AF increases the risk of potentially disabling or deadly ischaemic stroke (stroke caused by a blood clot) by nearly 500 percent. For valuable resources and information about living with atrial fibrillation, visit myafibexperience.org

Some abnormal rhythms are self-limiting and mild, whereas others are serious and potentially life threatening. Palpitations, especially when associated with other symptoms, should be checked by a doctor. Treatment may involve certain medication to prevent clotting or control heart rhythm, surgical as well as non-surgical procedures.

Watch a visual explanation of arrhythmia from the American Heart Association.

A cardiac arrest occurs when the heart stops beating. It may stop altogether or the rhythm may become chaotic preventing it from pumping effectively. Without blood circulation, brain damage begins after about four minutes and death usually occurs after about ten minutes. Cardiac arrest may occur as a result of a heart attack, but everyone who suffers a heart attack does not have a cardiac arrest or need CPR.

Other common causes of cardiac arrest are heart rhythm disorders, electric shock, drowning, drug overdose, suffocation and trauma.

Cardiac arrest may be reversed if CPR (cardiopulmonary resuscitation) is given and a defibrillator device is used to shock the heart and restore a normal heart rhythm within a few minutes.

What are the warning signs of a cardiac arrest?

  • Sudden loss of responsiveness (the person will be unconscious)
  • No normal breathing

What do you do if you witness a cardiac arrest?

A cardiac arrest is an extreme emergency! Immediate cardiopulmonary resuscitation (CPR) and defibrillation is needed to have any chance of survival. You can increase the person’s chances of survival by calling for an ambulance and giving immediate CPR.

Heart failure is due to the reduced ability of the heart to pump blood efficiently around the body. However, this does not mean the heart is about to fail or stop completely.

Heart failure can occur as a result of damage to the heart muscle resulting from a heart attack or high blood pressure, or as a viral infection, alcohol damage, valve problems or congenital heart disease.

When the heart does not pump efficiently, the heart has to beat faster and will gradually enlarge to cope with the workload. As a result, the heart weakens and the amount of blood pumped to the body is restricted.

The circulation becomes sluggish causing excess fluid normally excreted by the kidneys to be retained in the body.

The typical symptoms and signs for heart failure include shortness of breath which may be more obvious on exertion or when lying flat, swelling around the ankles and legs, feeling weak and tired, poor appetite, and a dry cough may also be present due to fluid in the lungs. Excess fluid can cause unusual weight gain.

Watch a visual explanation of heart failure from the American Heart Association.

A heart attack happens when the heart muscle is starved of oxygen and nutrients. This typically happens when its own blood supply from the coronary arteries is cut off or significantly reduced. The cause of mostly coronary heart disease, where the arteries becomes narrowed and the arteries walls build up with plaque. I piece of the plaque can break off and form a blood clot, that can completely block the blood flow to the heart muscle.

I heart attack is a life-threatening medical emergency. If you think you or someone else is suffering a heart attack you should phone an ambulance immediately. Read more about the signs of a heart attack.

Ischaemia occurs when there is an inadequate supply of oxygen rich blood to an organ or tissue. This arises as blood vessels become hardened and narrowed because of atherosclerosis, causing obstructed flow of blood through an artery. Narrowing of the insides of arteries that supply the heart muscle leads to reduced blood flow to the heart muscle/tissue. The heart muscle cannot receive sufficient oxygen and other nutrients to do its work, resulting in angina or a heart attack. Ischaemic heart disease that results from poor blood flow to the heart is also referred to as coronary heart disease.