The ABC of Coronary Heart Disease
What is heart disease?
Coronary heart disease (CHD) happens when your arteries become narrowed by atherosclerosis. This causes a restriction in the supply of blood and oxygen supply to the heart, particularly when you exert yourself and the demands of the heart muscle increase.
What are the symptoms of heart disease?
The main symptom of coronary heart disease is angina, caused by insufficient oxygen reaching your heart muscle because of a reduction in blood flow. Angina is a feeling of heaviness, tightness or pain in the middle of your chest that may extend to, or just affect, your arms, neck, jaw, face, back or abdomen. It is most often experienced during exertion - for example if you run for a bus, play a game such as tennis or football, climb stairs or walk uphill. It may come on in cold weather, after a heavy meal or when you are feeling stressed. It can subside once you stop what you're doing or take medication. Unfortunately, for many people, the first indication that something is wrong is a heart attack, or myocardial infarction. This happens when the blood supply to a part of the heart muscle is interrupted or stops, usually because of a blood clot in the coronary artery. The pain of a heart attack is often severe and may also be mistaken for indigestion. However, unlike angina the pain doesn't subside when you rest. Other symptoms include sweating, light-headedness, nausea or breathlessness, which unlike angina are not alleviated by rest.
Identifying the symptoms
The following symptoms are by no means always due to coronary heart disease and could be harmless or caused by other medical conditions. However, if you experience any of them it's a good idea to make an appointment to see your doctor:
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' that 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?
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 :
Age: It has been recognized 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.
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, estrogen, protects against coronary heart disease during the reproductive years by creating a more favorable 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 estrogen - this natural protection can disappear.
If you take the contraceptive pill, for example, you should be aware that smoking and taking the pill increases your risk of heart attack and clotting problems such as thrombosis. Although the risk is still small, you should do your very best to quit smoking and consult your doctor before taking the pill.
Genes: If you have a family history of coronary heart disease or factors predisposing to heart disease such as high cholesterol levels (familial hyperlipidemia) or high blood pressure, you're more at risk of developing it yourself.
Ethnic background : If you are black or Asian you are more at risk of heart disease, although different underlying risk factors are at play for each group. If you are Asian you have a higher risk of developing diabetes, which is a risk factor for heart disease. If you are black you are more at risk of high blood pressure, another risk factor for heart disease.
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.
Weight : Even being moderately overweight increases your risk of coronary heart disease. This may be because you're more likely to develop diabetes, have raised blood cholesterol levels and high blood pressure. It's also more difficult to be physically active if you are carrying excess pounds.
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.
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.
Level of activity : Watching too much television and taking the car instead of walking both increases your risk of coronary heart disease by reducing 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.
Blood pressure: Blood pressure is the force of blood in your arteries and is determined by how hard your heart works and your blood vessels. High blood pressure (or hypertension) is when the pressure is persistently higher than it should be (above 140/90), 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 often 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:
Cholesterol: Cholesterol is a waxy, fatty substance made by your liver. It's 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's 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, and 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're 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, being overweight, drinking too much alcohol and not doing enough exercise.
Cholesterol and atherosclerosis: Atherosclerosis, a build up of fatty materials within the walls of arteries, is set off when LDL cholesterol undergoes a chemical reaction called oxidation - the same reaction that causes butter to go rancid. In your body oxidation is caused by free radicals, harmful molecules produced as a result of the normal metabolism that occurs within the body. Free radicals also come from ionizing radiation from sunrays, ozone and nitrous oxide from car exhausts and cigarette smoke. These free radicals contribute to atherosclerosis that result in heart disease.
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 that are involved in the development of atherosclerosis.
Raised homocysteine levels: Some people with coronary heart disease have raised levels of a substance called homocysteine - an amino acid (one of the building blocks that make up protein) that your body uses to build tissues. It's derived from another amino acid, called methionine, which is found in foods containing animal protein, such as meat, milk and eggs. Raised homocysteine levels are thought to damage the lining of arteries, a crucial step in the development of atherosclerosis. They have also been found to be a factor in the oxidation of cholesterol and also appear to increase blood clotting. These findings help explain how other risk factors may exert their damage; for instance, smoking and inactivity (both risk factors for heart disease) lead to raised homocysteine levels. High homocysteine levels may be caused by:
While there's no single cause and some contributing factors can't be altered, others are a consequence of our lifestyle, which we can change. Making small changes to your diet is one of the simplest and most effective ways to reduce your risk of CHD. You can do this by:
Reducing Fat in Diet : Reducing the proportion of fat in your diet, especially saturated fat, can help to reduce blood cholesterol levels. There is a strong link between high blood cholesterol levels and the risk of heart disease. Normal blood cholesterol levels are below 5.2mmol/l. You should aim to consume no more than 35 per cent of your total calories from fat; less than 10 per cent of all calories should be from saturated fat. Trans-fatty acids are a particular kind of fat produced when plant-based oils are hydrogenated to produce solid spreads, such as margarines. They are often found in confectionery and processed food like pastry, biscuits and cakes. They have been found to have the same effect on cholesterol levels as saturated fat and should be avoided as much as possible. Thankfully, many manufacturers have now modified processing techniques to keep these fats to a minimum. Check labels for hydrogenated fats. When reducing total fat, it's important not to cut fat completely from your diet. It's the old message of everything in moderation. In fact, essential fatty acids such as omega-3s, which are found in oily fish, have been shown to further reduce the risk of CHD.
How to modify your fat intake:
Fruit and vegetables : Fruit and vegetables are rich in many essential nutrients including vitamins C and E and carotenoids (which are all antioxidants). They have been shown to protect the heart by limiting the damaging effects of cholesterol on body tissues. Aim for at least five servings of fruit and vegetables a day. A serving of fruit is:
Studies of large groups of people in the US have shown that diets rich in wholegrain foods can reduce the risk of CHD by up to 30 per cent. You can include wholegrain foods in every meal by choosing wholegrain breakfast cereals, wholemeal bread and wholegrain varieties of pasta and rice.
Soluble fiber: Soluble dietary fiber, found in oats, beans and pulses, can help to lower cholesterol, although the effect is modest. These should be included as part of an overall healthy balanced diet at least 2-3 times each week.
Alcohol : Consuming moderate amounts of alcohol - between one and two units a day - has been found to reduce the risk of CHD. This is because alcohol affects the amount of cholesterol in the bloodstream and makes it less likely that clots will form. However, high intakes of alcohol are associated with increased risk. It's also worth noting that saving up your weekly units for a weekend binge does not offer the same benefits.
Soya protein : A diet that includes at least 25g of soya per day has been associated with reductions in some forms of cancer and CHD. Soya protein is also an excellent substitute for meat and is available in a convenient and tasty form in many ready-made meals. Another good source of soya protein is soya milk and yoghurt.
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