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What is heart disease, how is it treated and how can you prevent it?
Published 27/02/2003
Which Hapsburg monarch put his entire court on a low-cholesterol diet? How many heroines in Jane Austen novels take herbs to lower blood pressure? If you said none, you're right. Heart disease was largely unknown before the twentieth century. Its beginnings as a mass killer lay in the industrial revolution in the 18th and 19th centuries. The wave of mechanisation that swept through Europe and North America brought two critical changes: a massive decline in heavy physical labour, and a widespread availability of processed food.
A sedentary lifestyle and a high-fat, highly-processed diet turned out to be two of the main causes of coronary heart disease, which soon propelled itself to the top of the list of major killers in the Western world and remains there today.
The heart is a double-sided muscular pump. The right side pumps into the lungs, where it's oxygenated. The left side receives this oxygenated blood and pumps it around the rest of the body where the oxygen and other nutrients are used by the cells of the body's tissues and organs. The deoxygenated blood then travels back via veins, to the right side of the heart again.
In this way, the body's five or so litres of blood is continually being pumped through the body. Each side of the heart has two chambers – the ventricle (the main chamber, which does most of the pumping work), and the atrium (or auricle, a smaller chamber which pumps blood into the ventricle).
The heart.The heart is the hardest working organ in the body. It pumps about 70 times a minute, every minute of every day. That's over two and a half billion beats in an average lifetime. To keep pumping at this rate, the heart itself needs a constant supply of oxygen. Supplying the muscles in the heart are three coronary arteries that encircle the heart and divide into a series of smaller arteries. As long as these arteries are healthy, they can keep the heart supplied with oxygen – even when the heart is pumping harder than normal, for example during sex or exercise. But if there is disease of these arteries, and not enough blood gets through them to the heart muscle, then the heart starts malfunctioning.
Coronary heart disease is actually a disease of the arteries of the heart, rather than a disease of heart muscle itself. It is caused by a build-up of fatty deposits in the lining of the walls of arteries – a process known as atherosclerosis.
These fatty deposits (called plaques) can thicken, calcify and narrow the arteries to the point where they constrict the flow of blood through them. Sometimes a blood clot can form at these plaques, abruptly stopping the flow through them (called coronary thrombosis, or coronary occlusion.) The end result is to deprive the heart tissue of oxygen, which can damage it, sometimes permanently. Hence the alternative name 'ischaemic heart disease' (ischaemia means lack of oxygen).
Atherosclerosis – and ischaemic heart disease/coronary artery disease – is especially common in people who have a family history of the disease, and/or who smoke, have hypertension (high blood pressure), are overweight, are diabetic, or have higher than normal levels of cholesterol in their blood. It is more common in men over the age of 45, though over the age of about 70, its equally common in both sexes.
Coronary heart disease causes one or more of the following conditions, alone or in combination:
Atherosclerosis (heart disease and stroke together) accounts for 40 per cent of all deaths in Australia, making it the number one killer. Heart disease alone accounts for about 25 per cent of all deaths.
Angina is a pain, or feeling of discomfort, in the chest. It is usually felt in the centre of the chest, but may spread to the neck or arms (especially the left one) and sometimes the shoulders or back. It is often described as a feeling of 'tightness' or 'pressure' and can range in severity from a mild ache to severe pain. The pain is caused by chemicals produced when the heart muscle has to function with inadequate oxygen.
Typically, the pain comes on during physical exertion and stops when the exertion ceases. This is because during exercise, the heart needs more oxygen and is more susceptible to the reduced volume of blood flowing through the diseased arteries. Sometimes though, angina can occur at rest. This usually indicates that coronary artery disease is more extensive than if it occurs only during exertion.
As well as pain there may be other symptoms – sweating, a feeling of anxiety or fear, a pallor (paleness), or irregular heart rhythms (palpitations) felt as 'fluttering' in the chest.
Someone with angina should see their doctor or go to hospital straight away if:
There are other causes of chest pain – heart burn caused by a backflow of acidic material in the oesophagus (known as reflux oesophagitis), for example. So in hospital, doctors will do an electrocardiograph (ECG) of the heart. This is a sensitive measurement of the heart's electrical activity and it can tell whether the pain is angina and where the area of oxygen deprivation is.
If there is any doubt, there are other tests that can be done, usually when the person has recovered and is pain free. For example, the person can be put on an exercise machine and an ECG done to see how the heart performs during activity. This is known as a stress test.
Or a special x-ray may be taken after a catheter, inserted in the groin and threaded into the heart's arteries, is injected with radioactive dye. The dye fills the arteries and reveals their outline as well as areas of narrowing or blockages. This is called coronary angiography.
Treatment
If the pain does turn out to have been angina, there is a range of treatment options available. Often taken as an aerosol spray or as a pill placed under the tongue, these may be taken for symptom relief during an episode of angina. They can also be taken on an ongoing basis to prevent angina.
The main classes of drugs for angina in common use are:
There are also surgical treatments which are very effective, especially if the atherosclerosis is localised to just a few areas of the coronary arteries. Coronary bypass surgery involves a surgeon taking grafts from blood vessels in the legs or elsewhere, and joining them to either side of the affected artery areas – creating a bypass. In another technique known as coronary artery angioplasty, a tube containing an inflatable balloon is passed along the artery to the affected area. When the balloon is inflated, it widens the artery. Often, to keep the artery open, metal tubes called stents are then inserted.
These operations are usually done once the person has recovered from angina and is well enough to undergo the surgery. They will also need to modify their lifestyle; exercise, eat a low-fat diet, stop smoking, lose weight, control high blood pressure and lower blood cholesterol levels if they are too high.
A heart attack is the everyday term for myocardial infarction, which literally means 'death of heart muscle because of inadequate oxygen'. The root cause is the same as that behind angina - atherosclerosis of the coronary arteries. In myocardial infarction, the chest pain doesn't go away with rest, because the reduced or absent flow is severe enough to cause death of heart muscle.
A myocardial infarction may happen out of the blue, or it may occur in someone who has had angina for months or years with the problem getting more frequent or more severe. Just as with angina, a heart attack is often accompanied by sweating, pallor, and palpitations (abnormal heart rhythms felt in the chest). As well, there may be difficulty breathing and/or fainting or loss of consciousness.
In some cases, particularly in women, there ay be no pain at all. Instead there may be other symptoms – sweating, dizziness, palpitations, nausea and difficulty breathing, for example. In a significant number of cases, there are no symptoms at all and the heart attack is only diagnosed much later when an ECG or other test reveals damage caused to the heart by a previous 'silent' heart attack.
Myocardial infarction is a medical emergency because of the serious effects it can have on the functioning of the heart. The death of heart muscle can disrupt the heart's normal electrical activity and the heart may develop an arrhythmia – an abnormal rhythm. It is possible so much heart muscle may die that it can't pump properly. In either case, the person can suddenly collapse and may die. This is called a cardiac arrest (see cardiac arrest).
Even if the heart keeps working, it may not be working well and the symptoms of heart failure may develop (see heart failure). So a heart attack is a medical emergency. Anyone who suspects they may be having one needs to go to hospital as soon as possible, preferably by ambulance. The sooner they get to hospital, the better their chances of recovery.
In hospital they will usually be admitted into intensive care or a specialist cardiac unit. Tests such as blood tests, an ECG and special scans, can help measure the position and extent of the damage. They will be given pain relief, anti-angina medications, oxygen by mask, and drugs to stabilise any abnormal heart rhythms.
In some cases, special drugs that dissolve clots are given. These also increase the blood flow to the heart tissue, preventing further damage. Some hospitals offer emergency angioplasty, in which a catheter is threaded up into the blocked artery in the heart. A balloon attached to the catheter is opened, expanding the artery and then a stent – a wire mesh tube to keep the artery open – is inserted, which is designed to stay there permanently. Studies show that this procedure saves more lives than clot-dissolving drugs, as long as it's done quickly – within two hours of a heart attack – and the hospital is well trained in the procedure. (One problem is in about a third of cases, the blood vessel becomes blocked again by scar tissue and the procedure needs to be redone. Newer stents – so called 'drug eluding stents' – release drugs that help prevent the blockage from recurring.)
During an angioplasty, a wire mesh tube called a stent is inserted into the artery to hold it open.After a day or two, once the patient is stable and the pain has subsided, they will begin physical activity, health education and counselling programs. Most people are in hospital for about three to five days after a heart attack. The damaged part of the heart takes longer to heal – about six to eight weeks. Dead tissue isn't replaced with normal heart tissue, but with scar tissue.
Usually though, the heart can function well enough for the person to make a full recovery, but it may not work as well in periods of exertion as it once did.
They will probably need ongoing treatment with drugs (such as those earlier described for angina), and aspirin (which has been shown to reduce the likelihood of further attacks). They will need to modify their lifestyle – to reduce risk factors, exercise more, and eat a low-fat diet. Some people benefit from further surgical treatments such as coronary bypass surgery and angioplasty.
Having a heart attack is extremely stressful, and it can take months or more for a person to come to terms psychologically with their experience. Many people benefit from being involved with community heart support groups.
In a cardiac arrest, the heart suddenly stops functioning altogether and the affected person collapses unconscious. If they are not resuscitated quickly, brain damage and death follow. However, if there is a bystander who is familiar with cardiopulmonary resuscitation (CPR), they can often be revived.
A cardiac arrest may be caused by a massive myocardial infarction that destroys so much heart muscle that the heart simply stops. It can also be caused by a disturbance of the electrical system within the heart which prevents the heart pumping blood normally. These disturbances are called arrhythmias. Within the heart muscle, there is a system of nerve pathways responsible for spreading electrical impulses through the heart in an orderly way so that it contracts rhythmically and efficiently. This electrical system can be disrupted by injury or disease.
In 90 per cent of cases, coronary artery disease is the cause, but other causes include drugs, electric shock, or pulmonary embolism (blood clots in the lungs). The most serious of the arrhythmias is ventricular fibrillation – a condition in which the muscles of the heart contracts in a in a rapid, unsynchronised way. The result is a 'flutter' rather than a true beat and the heart pumps little or no blood.
Someone who has had a cardiac arrest
As a general rule – IF SOMEONE COLLAPSES UNCONSCIOUS, AND DOESN"T HAVE A PULSE, THEY HAVE PROBABLY HAD A CARDIAC ARREST.
Immediate action is needed to save the life of a person who has had a cardiac arrest. If they are not resuscitated, brain damage begins after four minutes and death usually occurs after 12 minutes. An ambulance should be called by phoning 000 (in Australia). Resuscitation should be commenced using Cardiopulmonary Resuscitation (CPR) – a technique that involves mouth-to-mouth respiration and chest compression, with the aim of keeping the person alive until the ambulance arrives. The paramedics take over ventilation using more sophisticated ventilating devices. They will use a device called a defibrillator to shock the heart in an attempt to re-establish the heart's normal rhythm. They will also give the person intravenous drugs and fluids and transport them to hospital.
If someone has a cardiac arrest and is treated promptly by someone who is competent at CPR, and if an ambulance gets there promptly, survival rates can be as high as 70 per cent. Unfortunately because of general ignorance about CPR in the community, survival rates in practice are closer to between 10 per cent and 15 per cent. So there is currently an ongoing campaign by health authorities to teach people about CPR.
If the cardiac arrest is due to a massive myocardial infarction and death of heart muscle, rather than ventricular fibrillation (or another similar sort of arrhythmia) there is much less chance of successful resuscitation.
Sometimes a cardiac arrest takes place when a person is already in hospital. It is a common occurrence in someone who has had a heart attack, for example. In hospital, an arrest victim has a much better chance of survival because treatment is administered more promptly.
This is a condition where the heart, weakened by disease, fails to pump as well as it should. (The name is a little confusing, because the heart doesn't fail outright and stop beating. That would be a cardiac arrest).
The most common cause of heart failure is death of heart muscle from coronary artery disease. It may result from a major heart attack, or a series of heart attacks. Or it may occur slowly and painlessly from coronary artery disease over a period of years. The heart muscle can also be weakened by a virus or by alcoholism. (A disease of heart muscle is known as a cardiomyopathy.) As well, structural defects in the heart may be to blame – a faulty heart valve, or a hole in the chamber of the heart in an infant, for example.
Some of these causes are reversible; that is, they can be treated and the heart function completely restored. But if the disease has caused heart muscle to die, then the disease is not reversible and the person will need ongoing treatment to relieve the symptoms.
A person with heart failure becomes tired and weak because their tissues are not receiving enough oxygenated blood. The reduced blood flow through the heart itself results in pooling upstream. The fluid from this pooled blood seeps into tissues, causing them to swell – a condition called oedema.
If just the left side of the heart fails, the condition is known as left ventricular failure or LVF (the ventrical is the main chamber of the heart). If both sides fail the condition is called congestive cardial failure (CCF). It is rare for the right side to fail on its own.
If the left side of the heart fails, there will be a pressure build up of blood in the veins of the lungs. This pressure build-up forces fluid into the airspaces of the lungs (pulmonary oedema) and the person experiences breathlessness, which is usually worse during physical exertion. Lying down can also cause the person to wake up breathless or coughing.
The right side of the heart normally pumps blood from the general circulation into the lungs. If the right side fails, blood pressure builds up in the general circulation and oedema tends to form around the ankles and legs and in the abdomen.
In the early stages, the heart may pump efficiently enough for a person to perform normal daily activities. The symptoms may only arise during physical exertion when the heart cannot cope with the extra pumping activity needed. But as heart failure worsens, the symptoms become more and more debilitating, until the person becomes bedridden and, in advanced cases, immobile. Fortunately the symptoms of heart failure can be well-controlled with drugs even when the condition is quite advanced.
Treatment
There are several different types of drugs that are often used in combination to treat heart failure.
Doctors use one or more of these drugs in combinations. The dosages and the combination may need to be changed from time to time. The person may also need to take drugs for other conditions such as angina, which often coexists with heart failure. In advanced cases, when drug treatment is not working, a heart transplant (from a donor who had died of some other condition) may be an option. To prevent rejection of the new heart, the recipient will need to take medications to suppress the immune system and these can have serious side effects. A shortage of donor hearts means that recipients have to carefully selected. Nevertheless, a heart transplant can allow some patients to lead active, healthy lives once again. The average survival period after a heart transplant is between ten and 20 years.
There are certain steps that will significantly lessen your chances of getting ischaemic heart disease/coronary heart disease:
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