What causes coronary heart disease?
The overwhelming cause of coronary heart disease is atherosclerosis. This is a build up of fatty materials within the walls of the arteries.
This occurs when the inner lining of your artery walls becomes furred with a thick, porridge-like sludge (atheroma) made up of fatty deposits of cholesterol, cell waste and other substances. These form raised patches on the artery wall known as 'plaques' which narrow the arteries reducing the space through which blood can flow. At the same time the blood becomes more prone to clotting.
The growing plaques may block the delivery of nutrients to the artery walls, causing them to lose their elasticity. This in turn may lead to high blood pressure, which also increases the risk of coronary heart disease.
Who is at risk of coronary heart disease?
Page 1 Scientists have still to unravel all the causes of heart disease. However, certain factors can increase your likelihood of developing it. These are known as risk factors.
Some risk factors you cannot do very much about - such as your age, your gender or your ethnic group. Risk factors you do have some control over are what you eat, whether you smoke and the amount of exercise you take. Key risk factors include:
Your age
It has been recognised that the risk of developing coronary heart disease increases with age. Atherosclerosis takes a long time to develop and the arteries naturally become less elastic as we age, often leading to a greater risk of high blood pressure.
Your gender
Many people think of coronary heart disease as being a male problem. However this is far from being the case. In fact coronary heart disease accounts for more deaths of women than any other disease.
The female sex hormone, oestrogen, protects against coronary heart disease during the reproductive years by creating a more favourable balance of blood fats and by contributing to the elasticity and health of the arteries. However, after the menopause - or following a total hysterectomy in which the ovaries were also removed as well as the uterus thus depriving the body of oestrogen - this natural protection can disappear.
Your genes
If you have a family history of coronary heart disease or factors predisposing to heart disease such as high cholesterol levels (familial hyperlipidaemia) or high blood pressure, you are more at risk of developing it yourself. However, it is important that lifestyle are examined to ensure modifications are not required.
Diabetes
If you have diabetes you are three times more likely to develop coronary heart disease. You are also more likely to have silent ischemia because diabetes can affect the nerves which send pain messages.
Being overweight and inactive
Both of these are separate risk factors for coronary heart disease and increase your risk of developing diabetes in middle age. Unfortunately, because in the early stages diabetes often has no symptoms, many people remain undiagnosed sometimes for years, during which time their arteries may be becoming more damaged.
Of course, other risk factors such as high blood pressure, raised cholesterol levels, smoking, being overweight and physical inactivity still apply if you have diabetes. In fact, Diabetes appears to be an extra risk - which may possibly amplify the risk of these other factors.
Your shape
Apple-shaped people who carry fat around their waist are more at risk of coronary heart disease than pear-shaped people who carry excess weight around their hips. This pattern of fat distribution, in some people, may be a result of insulin resistance, in which the body is unable to use insulin properly, even if you do not have fully fledged diabetes.
The tendency to a particular shape is largely inherited, so if one or both your parents are 'apples', it's worth taking particular care over diet and exercise to lose excess fat.
Your blood pressure
Blood pressure is the force of blood in your arteries. The pressure of blood travelling in the arteries is determined by how hard your heart works and the health of your blood vessels.
High blood pressure (or hypertension) is when the pressure is persistently higher than it should be (above 140/85 or 130/80 if diabetic), causing increased strain on your arteries. Over time the force of the blood flowing through the arteries causes the smooth lining to roughen and the walls to become thicker. This in turn causes the arteries to narrow and become less elastic.
Because high blood pressure is often silent - i.e. it causes no symptoms - it's important to have your blood pressure checked regularly, so if it is raised you can take steps to reduce it.
You are more at risk of high blood pressure if:
- You have a family history of the condition.
- You are overweight.
- Your drink heavily.
- You eat a salty diet.
- You are under stress or have anxiety.
- You have kidney disease.
- You are black African or African-Caribbean.
Your cholesterol level
Causes of high blood cholesterol levelsEating a fatty diet, especially one that is high in saturated (animal) fats. Chronic renal (kidney) failure. Heavy drinking or alcohol abuse. The inherited condition familial hyperlipdaemia. Cholesterol is a waxy, fatty substance made by your liver. It is also present in some foods such as animal fats, eggs and shellfish. Your body needs some cholesterol to produce hormones, to produce the bile needed to digest fat. It is also the main ingredient of cell membranes.
Cholesterol travels around your bloodstream in special proteins called lipoproteins. There are two types:
Low density lipoproteins or LDL also known as 'bad cholesterol' which carries cholesterol to your body's cells.
High density lipoproteins or HDL also known as 'good cholesterol' which helps clear excess cholesterol from your arteries and carries it back to your liver to be destroyed.
If you have high levels of LDL and low levels of HDL you are more at risk of heart disease. Factors predisposing towards unhealthy cholesterol levels include eating a diet high in saturated (animal) fats and/or transfats found in processed foods, overweight and lack of physical activity.
Cholesterol and atherosclerosis
(Build up of fatty materials within the walls of arteries)
In your body oxidisation is caused by free radicals, harmful molecules produced as a result of damage by chemicals such as nicotine, high levels of blood glucose, viruses, pollution or physical factors such as injury or high blood pressure. When this happens a complex chemical chain reaction is set in motion that results in the development of atherosclerosis.
Smoking
Smoking increases your risk of having a heart attack two or three-fold. In fact if you are under 50 and smoke you are five times more likely to die of coronary heart disease than a non-smoker.
There are several reasons for this. Nicotine triggers the release of the stress hormone adrenalin, which raises your heart rate and blood pressure, increasing your heart's need for oxygen. Carbon monoxide, found in tobacco smoke, displaces oxygen from your bloodstream - depriving your heart of oxygen.
Other chemicals in cigarette smoke trigger the release of free radicals, the harmful molecules which are involved in the development of atherosclerosis.
Your weight
Even being moderately overweight increases your risk of coronary heart disease. This may be because overweight people are more likely to develop diabetes. You are also more likely to have raised blood cholesterol levels and high blood pressure, because excess weight increases the amount of work your heart has to do. It's also more difficult to be physically active if you are carrying excess pounds - a factor which can protect you against coronary heart disease.
Your activity level
Watching too much television, taking the car instead of walking ,sitting down too much, all increase your risk of coronary heart disease by reducing your circulation and limiting the amount of oxygen and nutrients delivered to your body's cells. Lack of activity also decreases your body's ability to extract oxygen from your blood, weakens your bones (leading to a risk of osteoporosis ) and your muscles - and encourages high cholesterol levels.
Treatment
Treatment for coronary heart disease varies depending on your age, the state of your arteries, the severity of your symptoms, and a variety of other factors.
In many cases coronary heart disease can treated with drugs. In others, surgery or a procedure to open up your blocked blood vessels may be necessary. Click on the links to the right to find out more about treatment and medications.
Surgery
Coronary heart disease can frequently be controlled with drugs alone. However, if the blood vessels have become very narrowed or if drug treatment alone is not controlling symptoms, surgery may be needed to open up or replace the blocked arteries.
Laser surgery
In the past few years an experimental technique known as transmyocardial laser revascularistion (TMR) has been developed. The technique, which involves using a laser beam to create channels in the wall of the left ventricle allowing oxygen rich blood to flow to the heart muscle, was initially greeted with great excitement because it offered the promise of treating the heart itself rather than the arteries.
Heart transplant
You may be offered a heart transplant if:Your heart muscle has become weakened (cardiomyopathy). Your heart's blood vessels are blocked and your heart muscle is damaged. Apart from your heart problems, you are in otherwise good health. Other treatments have been tried or excluded. You are under 60 (in most cases). You are able and willing to stick to lifestyle changes necessary after the transplant. In a heart transplant, the heart is removed and replaced with a healthy heart from a donor. A lung transplant may be done at the same time - a heart/lung transplant.
In the past, heart transplants sometimes failed because the person's immune system rejected the transplanted heart. However, with the use of drugs to prevent rejection, heart transplants are now extremely successful. Unfortunately a shortage of donors means that a heart transplant is usually only recommended if you have advanced heart disease.
After a transplant you will need to take immunosuppressive drugs for the rest of your life, to stop your body rejecting the transplant, as well as other drugs to help your body fight off infections. The doctor will monitor your new heart at regular intervals for any signs of rejection.
Prevention approaches
Prevention is always better than cure. This section outlines things you can do to help yourself to a healthier heart. Even if you've already been diagnosed with heart disease, making lifestyle changes can help you live a longer, healthier and more enjoyable life.
Adopting a healthier lifestyle is not about denying the things you enjoy, make vast changes such as joining a gym, becoming a vegetarian or eating nothing but 'health foods.' Small, easily achievable adaptations such as becoming more active in your everyday life and learning to enjoy fresh, wholesome food can make a tremendous difference to your wellbeing and improve the health of your heart.
Best of all, most of the steps outlined improve several different risk factors. For example becoming more active helps to reduce your blood pressure, improves your cholesterol level and by boosting your metabolism, helps control your weight - all of which can significantly reduce your risk of coronary heart disease. Click on the links to the right to find out more.
Activity
It is important that you visit your GP before you start any exercise programme.
Being active is absolutely essential for a healthy heart - for the simple reason that your heart is a muscle. Even if you haven't been active for some time, your heart can become stronger, so that it is able to pump more efficiently giving you more stamina and greater energy.
Becoming more active will also improve the ability of your body's tissues to extract oxygen from your blood, help you maintain healthy levels of blood fats and speed your metabolism.
Types of exercise
Aerobic (cardiovascular) exercise
Particularly important to prevent coronary heart disease is aerobic or cardiovascular exercise. This is any kind of activity that increases your breathing rate and gets you breathing more deeply. These activities include: walking, running, swimming , dancing or any of the aerobic (cardiovascular) machines at the gym such as the rowing machine, treadmill, stepper or elliptical trainer.
These are designed to increase the strength of your heart muscle by improving your body's ability to extract oxygen from the blood and transport it to the rest of the body. Aerobic exercise also enhances your body's ability to use oxygen efficiently and to burn (or metabolise) fats and carbohydrates for energy.
Strength (resistance training) exercise
Strength exercise (or resistance training) helps to make your muscles stronger, strengthens your bones and protects your joints from the risk of injury (because muscles protect the joints). This type of exercise may involve the use of free weights and weights machines such as those found in the gym - or any kind of activity in which you load your muscles. For example, carrying heavy shopping bags or exercises such as press-ups lunges and squats, and some of the exercises involved in yoga which use your body weight, are all good for resistance.
Resistance training does not increase the fitness of your heart like aerobic exercise. What it can do is help control your weight because muscular tissue burns more calories than fat. This type of exercise is not recommended for people with uncontrolled high blood pressure or heart disease; so if you are affected, check with your doctor.