Atherosclerosis is a potentially serious condition where the body's medium and large
arteries become clogged up by fatty substances, such as cholesterol.
These substances are called plaques or atheromas.
The circulation system is made up of arteries and veins. The blood is pumped from the heart and through the aorta (the main artery leading from the heart) before travelling through smaller and smaller arteries that branch off from each other.
The blood passes into tiny blood vessels, known as capillaries, where the oxygen in the blood is transferred into the cells of your body's tissues and organs. The blood returns to the heart through the veins.
Hardening and narrowing of the arteries is potentially dangerous for two reasons:
- Restricted blood flow to an organ can damage it and stop it functioning properly.
- If a plaque ruptures (bursts) it will cause a blood clot to develop at the site of the rupture. The blood clot can block the blood supply to an important organ, such as the heart, triggering a heart attack, or the brain, triggering a stroke.
Cardiovascular disease (CVD)
Atherosclerosis is a major risk factor for many different conditions involving the flow of blood. Collectively, these conditions are known as cardiovascular disease (CVD). Examples of CVD include:
- peripheral arterial disease: where the blood supply to your legs is blocked, causing muscle pain
- coronary heart disease: where the main arteries that supply your heart (the coronary arteries) become clogged up with plaques
- stroke: a very serious condition where the blood supply to your brain is interrupted
- heart attack: a very serious condition where the blood supply to your heart is blocked
How common is atherosclerosis?
It is hard to estimate exactly how common atherosclerosis is. This is because it does not cause any noticeable symptoms until it reaches an advanced stage and triggers the onset of a related health condition, such as heart disease. However, it is thought that almost all adults have some degree of atherosclerosis.
A person’s arteries naturally get harder as they get older. Therefore, atherosclerosis tends to be more common in people who are over 40 years of age.
Atherosclerosis is more common in men than in women. It is thought that this is because the sex hormones that are used in the female reproductive cycle, such as oestrogen, provide protection against the effects of atherosclerosis.
Risk factors that can dangerously accelerate the process of atherosclerosis include:
- a high-fat diet
- a lack of exercise
- being overweight or obese
- having either type 1 or type 2 diabetes
- having high blood pressure (hypertension)
Left untreated, the outlook for atherosclerosis is poor. In England and Wales, atherosclerosis (and the resulting cardiovascular diseases) is the single biggest cause of death, accounting for one in three of all deaths.
Each year, in England and Wales, an estimated 124,000 deaths are caused by CVD. Around 39,000 of these deaths occur in people who are under 75 years of age. Also, for every death, CVD causes two non-fatal, but serious, complications, such as a stroke or heart attack.
Treatment for atherosclerosis aims to prevent the condition from worsening to the point at which it can trigger a serious CVD, such as a heart attack. This can be achieved by using a combination of lifestyle changes, such as eating a healthier diet, and certain medications.
Symptoms of atherosclerosis
Atherosclerosis does not usually produce any symptoms until your blood circulation becomes restricted, or blocked, leading to the onset of cardiovascular disease (CVD). The type of CVD and its associated symptoms will depend on where the blockage occurs.
Conditions that are known to be caused by atherosclerosis include:
- peripheral arterial disease
- heart attack
The conditions and their associated symptoms are described below.
Peripheral arterial disease
Peripheral arterial disease, also known as peripheral vascular disease, is a condition that occurs when there is a blockage in the arteries of your limbs (in most cases, your legs).
The most common symptom of peripheral arterial disease is pain in your legs. This is usually in one or both of your thighs, hips or calves.
The pain can feel like a cramp, or a sensation of dullness or heaviness, in the muscles of your legs. The pain usually comes and goes and is usually worse when doing exercise that uses your legs, such as walking or climbing stairs.
This is because physical exertion increases the need for blood to be supplied to your muscles but, due to your narrowed arteries, this demand cannot be met, resulting in the symptoms of pain.
Other symptoms of peripheral arterial disease include:
- weakness, or numbness, in your legs
- having sores on your feet or legs that never heal
- a change in the colour of the skin on your legs
- hair loss on your legs or feet
- thickening of your toenails
- erectile dysfunction, also known as impotence (in men)
Angina is similar to peripheral arterial disease in that it is caused by a reduced blood supply to the heart.
The most common symptom of angina is a feeling of pain, or discomfort, in your chest. The pain can feel tight, dull or heavy, and usually passes within a few minutes.
The pain that is associated with angina can spread from your chest to your left arm, neck, jaw and back. It usually follows a period of physical activity, or emotional stress. In some cases, the pain can develop during cold weather or after eating a meal. Factors that can provoke the symptoms of angina are known as angina triggers.
Some people with angina may also experience symptoms of:
- belching (burping)
The onset of angina symptoms is sometimes referred to as an angina attack.
If atherosclerosis weakens the walls of your blood vessels, it can lead to the formation of an aneurysm (a bulge in a blood vessel). If the aneurysm grows too large, there is a danger that it will rupture (split), which can cause potentially fatal internal bleeding and organ damage.
An aneurysm can develop anywhere in the body, but the two most common types of aneurysm are:
- an intracranial aneurysm (also known as a cerebral aneurysm), which develops inside the brain
- an aortic aneurysm, which develops inside the aorta (a large blood vessel that runs down the abdomen and transports blood away from your heart)
You should dial 999 immediately to request an ambulance if you suspect that you, or someone you know, has experienced a ruptured aneurysm.
If an aortic aneurysm ruptures, you will experience a sudden and severe pain in the middle or side of your abdomen (stomach). In men, the pain can also radiate down into the scrotum (the sac that hangs between the legs and contains the testicles).
Symptoms of a ruptured intracranial aneurysm usually begin with a sudden and severe headache, which has been described as like being hit on the head, resulting in a blinding pain that may be unlike anything you have ever experienced before.
If one of the plaques in your coronary arteries ruptures (splits) it could create a blood clot. If the blood clot blocks the supply of blood to your heart, it will cause you to have a heart attack.
You should dial 999 immediately if you suspect that you, or someone you know, is having a heart attack.
The symptoms of a heart attack include:
- chest pain that is usually located in the centre of your chest and can feel like a sensation of pressure, tightness or squeezing
- pain in other parts of the body can feel as though it is travelling from your chest to your arms (usually the left arm is affected, although it can affect both arms), jaw, neck, back and abdomen (stomach)
- an overwhelming sense of anxiety (similar to a panic attack)
- shortness of breath
Blood clots can also block the supply of blood to your brain, causing a stroke.
The main symptoms of a stroke can be remembered by using the acronym FAST, which stands for:
- Face: the face may have fallen on one side, the person may be unable to smile, or their mouth or eye may have drooped
- Arms: due to a weakness, or numbness, of the arms, the person with a suspected stroke may not be able to raise both of their arms and keep them raised
- Speech: the person’s speech may be slurred
- Time: it is time to dial 999 immediately if you see any of these signs or symptoms
Symptoms in the FAST test are successful in identifying about 90% of all strokes.
You should dial 999 immediately to request an ambulance if you suspect that you, or someone you know, is having a stroke.
Other signs and symptoms may include:
- communication problems (difficulty talking and understanding what others are saying)
- problems with balance and coordination
- difficulty swallowing
- severe headaches
- numbness or weakness resulting in complete paralysis (lack of sensation) in one side of the body
- loss of consciousness (in severe cases)
There is also a condition that is related to stroke, known as a transient ischaemic attack (TIA). This is where the blood supply to the brain is temporarily interrupted, causing a 'mini-stroke'.
The symptoms of a transient ischaemic attack (TIA) are the same as those of a stroke, but they only last for between a few minutes and a few hours before disappearing completely. However, a TIA should never be ignored because it is a serious warning sign that there is a problem with the blood supply to your brain.
Causes of atherosclerosis
Over time, as you get older, your arteries naturally begin to harden and get narrower, leading to atherosclerosis. However, there are many factors that can dangerously accelerate this process. These are described below.
High-fat diets and cholesterol
Cholesterol is a type of fat that is essential for the functioning of the body. Cholesterol helps to produce hormones, to make up cell membranes (the walls that protect individual cells) and to protect nerve endings.
There are two main types of cholesterol:
- Low-density lipoprotein (LDL) is mostly made up of fat, plus a small amount of protein. This type of cholesterol can block your arteries, so it is often referred to as 'bad cholesterol'.
- High-density lipoprotein (HDL) is mostly made up of protein, plus a small amount of fat. This type of cholesterol can help to reduce any blockage in your arteries, so it is often referred to as 'good cholesterol'.
Most of the cholesterol that your body needs is manufactured by your liver. However, if you eat foods that are high in saturated fat, the fat is broken down into LDL ('bad cholesterol').
Foods that are high in saturated fat include:
- processed meat
The LDL cholesterol sticks to your artery walls in the form of fatty deposits which, over time, gradually build up, narrowing, or completely blocking, your blood supply. The fatty deposits are also known as plaques or atheroma.
As well as a high-fat diet, a lack of regular exercise, being obese and drinking excessive amounts of alcohol can also increase the levels of LDL cholesterol in your body. The medical term for having high cholesterol is hyperlipidemia.
Smoking can damage the walls of your arteries. If your arteries are damaged by smoking, blood cells, known as platelets, will form at the site of the damage to try to repair it. This can cause your arteries to narrow.
Smoking also decreases the blood's ability to carry oxygen around your body, which increases the chances of a blood clot occurring.
High blood pressure
If you have high blood pressure (hypertension) it will damage your arteries in the same way as cigarette smoke. Your arteries were designed to pump blood at a certain pressure. If that pressure is exceeded, the walls of the arteries will be damaged. High blood pressure can be caused by:
- being overweight
- drinking excessive amounts of alcohol
- a lack of exercise
If you have poorly controlled type 1 or type 2 diabetes, the excess glucose in your blood can damage the walls of your arteries.
Being overweight or obese does not directly increase your risk of developing atherosclerosis and cardiovascular disease (CVD), but it does lead to related risk factors that do. In particular, people who are overweight or obese:
- have an increased risk of developing high blood pressure
- tend to have higher levels of cholesterol as a result of eating a high-fat diet
- have an increased risk of developing type 2 diabetes
Lack of exercise
As with being overweight or obese, a lack of exercise is not directly related to an increased risk of atherosclerosis and CVD. However, it is linked to an increased risk of being overweight or obese and having high blood pressure (hypertension).
Drinking an excessive amount of alcohol can cause high blood pressure (hypertension) and raised blood cholesterol levels, increasing your risk of developing atherosclerosis and CVD.
Most heavy drinkers also tend to have other unhealthy habits, such as smoking, eating a high-fat diet and not taking enough exercise.
If you have a first-degree relative (a parent, or a brother or sister) with atherosclerosis and CVD, you are twice as likely to develop similar problems compared with the population at large.
Rates of high blood pressure and diabetes are higher among people of African and Afro-Caribbean descent. This means that people in this group also have an increased risk of developing atherosclerosis and CVD.
People of South Asian descent (those from India, Bangladesh, Pakistan and Sri Lanka) are five times more likely to develop diabetes compared with the population at large. Again, this increases this group’s risk of developing atherosclerosis and CVD.
Research that was carried out during 2009 suggested that air pollution, in particular traffic pollution, can cause a slight increase in levels of atherosclerosis.
Researchers found that people living within 50 metres of a major road had higher levels of atherosclerosis than would otherwise be expected.
Atherosclerosis does not usually produce any symptoms until a cardiovascular disease (CVD) occurs. Therefore, those at risk of developing atherosclerosis should be tested for the condition. Screening allows treatment to be given in order to reduce the risk of CVD developing.
Your GP may recommend that you are screened if they feel that you are at significant risk of developing CVD. Risk factors include:
- being over 40 years of age
- being overweight or obese
- being a smoker, or having a previous history of heavy smoking
- eating a high-fat diet
- having high blood pressure (hypertension)
- having diabetes
- having a family history of heart disease, high blood pressure or diabetes
There are several tests that can be used to assess your level of existing atherosclerosis and your risk of developing CVD. Tests that you may have include:
- blood tests, which can measure the amount of cholesterol in your blood, plus the amount of glucose if you are diabetic
- blood pressure tests
- a measurement of your weight and waist size
Your GP may also carry out an ankle-brachial index test. This is a form of blood pressure test where the blood pressure in your ankle is compared to the blood pressure in your arm. A difference between the two readings may suggest that atherosclerosis is restricting the blood supply to your legs and that you have peripheral arterial disease.
If it is felt that your risk of developing CVD is very high, or if you are experiencing symptoms that are associated with CVD, further tests may be required to confirm the level of atherosclerosis, and locate the sites of any potential blockages in your arteries. These tests are explained below.
An electrocardiogram (ECG) measures the electrical activity of your heart. This test can measure how well your heart is functioning and it can often detect the presence of heart disease.
An ultrasound scanner uses sound waves to build up a picture of the inside of your body. This can be used to measure your blood pressure at different points in your body. Any variation in pressure could point to the site of a blockage in your arteries. Ultrasound tests can also be used to study the larger arteries.
An angiogram is a test in which you are injected with a special dye that can be seen on X-rays. The test is used to see how the blood flows through your body.
Computed tomography (CT) scan
A computed tomography (CT) scan takes a series of X-ray images and uses a computer to assemble them into a more detailed three-dimensional image. It can often detect narrowing, or hardening, in the larger arteries.
An ophthalmoscopy is a type of eye test where an instrument called an ophthalmoscope is used to examine the blood vessels in the back of your eye. The ophthalmoscope can sometimes detect hardening of the blood vessels in your retina (the retina is the light-sensitive layer at the back of the eye).
If it is felt that you are at significant risk of developing a cardiovascular disease (CVD) due to atherosclerosis, you will be advised to make lifestyle changes in order to help reduce your risk, such as changing your diet and taking more exercise.
See Atherosclerosis - prevention for more information and advice about the lifestyle changes that are recommended to reduce your risk of developing CVD.
There are several medications available to treat many of the underlying causes of atherosclerosis, such as a high cholesterol level and high blood pressure (hypertension).
Depending on your individual circumstances, you may only need to take one medication, or you may need to take a combination of different medications.
High blood pressure (hypertension)
The most widely used medications for treating high blood pressure are outlined below.
Angiotensin-converting enzyme (ACE) inhibitors
Angiotensin-converting enzyme (ACE) inhibitors work by blocking the actions of some of the hormones that help to regulate blood pressure.
By stopping these hormones from working, ACE inhibitors help to reduce the amount of water in your blood, as well as widening your arteries, both of which will bring your blood pressure down.
ACE inhibitors are not suitable for:
- women who are pregnant or breastfeeding
- people with conditions that affect the blood supply to their kidneys
- those with a history of heart disease
The side effects of ACE inhibitors include:
- tiredness or weakness
- a persistent dry cough
Most of these side effects should pass in a few days, although some people find that they continue to have a dry cough.
If the side effects of ACE inhibitors become troublesome, angiotensin-2 receptor antagonists may be recommended. They work in a similar way to ACE inhibitors.
Calcium channel blockers
Calcium channel blockers are an alternative type of medication to ACE inhibitors. They work by relaxing the muscles of your artery walls, which causes your arteries to widen and reduces your blood pressure.
Calcium channel blockers are not recommended for people with a history of heart disease, liver disease or circulation problems. Side effects of calcium channel blockers include:
- a flushed face
- swollen ankles
- skin rashes
However, these side effects should pass within a few days, once your body gets used to the medication.
You should not drink grapefruit juice if you are taking calcium channel blockers because this can cause your blood pressure to fall.
Thiazide diuretics work by reducing the amount of water in your blood and widening the walls of your arteries. They are not recommended for pregnant women or people with gout (a type of arthritis where crystals develop inside the joints).
Thiazide diuretics have been known to reduce the level of potassium in your blood, which can interfere with your heart and kidney functions. They can also raise the level of sugar in your blood, which could lead to diabetes.
Therefore, you will probably be advised to have blood and urine tests every six months so that your potassium and blood sugar levels can be monitored.
A few men reported that they could not get or maintain an erection while taking thiazide diuretics, although this side effect resolved once the medication was withdrawn.
See Blood pressure (high) - treatment for more information and advice about the treatments that are available for high blood pressure.
High cholesterol levels
Statins are a type of medication that is used to lower your blood cholesterol level. Statins block the effects of an enzyme in your liver called HMG-CoA reductase, which is used to make cholesterol.
Statins sometimes have mild side effects including:
- abdominal pain
Occasionally, statins can also cause muscle pain, weakness and tenderness. You should contact your GP if you experience these symptoms because your dosage may need to be adjusted.
If you have high blood cholesterol, you may need to take statins indefinitely.
See High cholesterol - treatment for more information and advice about the treatments that are available for high cholesterol.
Preventing blood clots
As many of the serious complications that arise from atherosclerosis, such as a heart attack or stroke, are associated with blood clots, you may be given medication to help reduce the risk of you having a blood clot.
Medications that are used to prevent blood clots developing are known as antiplatelets. Platelets are tiny particles in the blood that help it to clot. Antiplatelets work by reducing the 'stickiness' of platelets.
You may be advised to take low-dose aspirin which, as well as being a painkiller, has blood-thinning properties.
If testing shows that you have a higher than average risk of developing a blood clot, you may be given an additional antiplatelet medication called clopidogrel. Clopidogrel can also be used if you are allergic to aspirin.
The side effects of clopidogrel include:
- abdominal pain
Surgery may be required if certain important blood vessels become narrowed. These are the:
- coronary arteries, which supply blood to your heart (narrowing of your coronary arteries can trigger a heart attack)
- carotid arteries, which supply blood to your brain (narrowing of your carotid arteries can trigger a stroke)
Coronary angioplasty is a type of surgery that can be used to widen your coronary arteries. During a coronary angioplasty, a long, flexible plastic tube called a catheter, which is about the width of the lead in a pencil, is inserted into a blood vessel, either in your arm or groin.
X-ray is used to guide the tip of the catheter to your heart, or to the point where the narrowing of the artery has occurred. A balloon that is attached to the catheter is inflated in order to widen the artery. A small metal tube called a stent is often used to help keep the artery open.
Coronary artery bypass graft
A coronary artery bypass graft (CABG) is an alternative surgical technique that can be used to treat narrowing of the coronary arteries. During a CABG, healthy blood vessel segments (grafts) are taken from other parts of the body in order to bypass the blocked artery.
Segments of vein that are taken from your legs, arms and chest are used to create a new channel through which the blood can be directed past the blocked part of the artery. This enables more blood to get through to the heart muscle.
Surgery is usually only recommended to widen the carotid arteries if you have experienced previous symptoms related to a blocked blood supply, such as a previous stroke or transient ischaemic attack (TIA).
Unlike the coronary arteries, preventative surgery on the carotid arteries is not usually recommended, except in cases where testing shows very high levels of narrowing.
This is due to the fact that a number of large medical studies have found that the benefits achieved in reducing the risks of a stroke in most people without any symptoms are outweighed by the risks associated with surgery (one of which is stroke). Therefore, in some cases, surgery has a greater risk of causing a stroke than preventing it.
If you do have symptoms, it is usually recommended that surgery is carried out during the first 14 days after the onset of your symptoms.
A carotid endarterectomy is the most commonly used method of widening the carotid artery (the main artery in your neck). During the procedure the surgeon will make an incision (cut) into the narrowed part of the artery. The inner lining of the artery is then removed, along with any plaque inside it.
Most surgeons sew a patch into the opening in the artery in order to widen this section of the artery. The patch may be taken from a vein in your thigh or it might be synthetic (man-made). Using a patch can reduce your risk of having a stroke after the operation, as well as reducing the likelihood of restenosis (the artery becoming narrowed again).
Your surgeon will stitch up the artery and check for any bleeding. Once any bleeding has stopped, the clamps will be removed and the incision in your neck will be closed up.
A carotid angioplasty is an alternative method of widening the carotid artery. The procedure is usually carried out under local anaesthetic, and uses a balloon catheter (a thin plastic tube with an inflatable balloon at one end). The catheter is inserted into your femoral artery (the body’s main blood vessel) in your groin.
Under the guidance of X-ray, the catheter is threaded up into your femoral artery until it reaches your carotid artery. The balloon is then inflated up to around 5mm in diameter. This expands the artery, clearing the narrowing so that blood is able to flow through it again.
Carotid angioplasty is a less invasive type of surgery than carotid endarterectomy, so you will experience less post-operative pain and have a faster recovery time.
However, research carried during 2009 found that people who had a carotid angioplasty were more likely to have re-narrowing of the carotid artery compared with those who had a carotid endarterectomy. You should discuss the advantages and disadvantages of both types of surgery with your surgeon.
Making lifestyle changes is a very effective way of preventing, or reversing, the process of atherosclerosis, as well as reducing your risk of developing a cardiovascular disease (CVD), such as a coronary heart disease, heart attack or stroke.
There are five ways you can help reduce your risk of developing further coronary heart disease:
- stop smoking (if you smoke)
- eat a healthy diet
- take regular exercise
- lose weight (if you are overweight or obese)
- moderate your consumption of alcohol
These lifestyle changes are discussed in more detail below.
If you smoke, it is strongly recommended that you quit as soon as possible. The NHS Smokefree website can provide you with support and advice. Your GP will also be able to recommend and prescribe medication that can help you give up.
It is recommended that you eat two to four portions of oily fish a week. Oily fish contains a type of fatty acid called omega-3. Omega-3 can help lower your cholesterol levels.
Good sources of omega-3 include:
If you are unable, or unwilling, to eat oily fish, your GP may recommend that you take an omega-3 food supplement. However, you should never take a food supplement without first consulting your GP. Some supplements, such as beta-carotene, can be harmful.
It is also recommended that you eat a Mediterranean-style diet. This means that you should eat more bread, fruit, vegetables and fish, and less meat. Replace butter and cheese with products that are vegetable and plant-oil based, such as olive oil.
If you are overweight, or obese, you should lose weight, and maintain a healthy weight by using a combination of regular exercise and a calorie-controlled diet.
If you drink alcohol, you should not exceed the recommended daily limits (3-4 units a day for men, and 2-3 units a day for women).
A unit of alcohol is roughly half a pint of normal strength lager, a small glass of wine or a single measure (25ml) of spirits. Regularly exceeding the recommended alcohol limits will raise your blood pressure and your cholesterol level, which will increase your risk of developing CVD.
You should contact your GP if you find it difficult to moderate your drinking. Counselling services and medication can help you to reduce your alcohol intake.
A minimum of 30 minutes of vigorous exercise a day, five times a week, is the recommended amount of exercise. The exercise should be strenuous enough to leave your heart beating faster, and you should feel slightly out of breath afterwards.
Activities that you could incorporate into your exercise programme include:
- brisk walking
- hill climbing
If you find it difficult to achieve 30 minutes of exercise a day, you should start at a level that you feel comfortable with. For example, you could do five to ten minutes of light exercise a day and then gradually increase the duration and intensity of your activity as your fitness begins to improve.