Ischaemic heart disease, angina and heart attacks
22 June 2011
What is Ischaemic heart disease?
Ischaemic heart disease is the name given to the condition which causes narrowing of the coronary arteries sufficient to reduce blood flow to the heart muscle. The coronary arteries are the main blood vessels which supply the heart muscle itself with blood, which gives it the oxygen the muscle needs to pump. As the heart is never idle, this makes the coronary arteries pretty important blood vessels!
Ischaemic heart disease used to be almost unknown until the 1920’s. This was because life expectancy was shorter, diet was very different, and hardly anyone had a really sedentary lifestyle. No computers in those days! From the 1940’s onwards however, as smoking proliferated during the war, diet changed, affluence developed and life expectancy increased, so coronary heart disease came forward as a feared condition in which the sufferer could drop dead as the first sign of the illness!
Narrowing of blood vessels occurs due to a process called atherosclerosis. Fatty cholesterol deposits line the arteries and create “plaques” on the wall. These plaques can narrow arteries after a while and result in limitation of blood supply. The same process can occur in the main arteries of the head and neck, in which case people can also be susceptible to stroke. Risk of stroke and ischaemic heart disease therefore go hand in hand.
What is angina?
Angina is the name given to the symptoms patients get when one or more of the coronary arteries is narrowed to the point where blood flow to the heart muscle is reduced. Because the heart muscle has to work harder when people exercise, patients typically get their symptoms on exertion. Depending how badly the artery is narrowed, the symptoms may come on after mild or more marked exertion.
The symptoms themselves vary greatly from patient to patient. This is because the brain isn’t used to getting messages from the heart muscle (you can’t feel your blood rushing around inside can you?) and so it has trouble working out where the complaint is coming from. The typical symptoms consist of a symmetrical and central heavy or pressure sensation in the chest on exertion which resolves with rest. But because the brain is having trouble identifying the source, patients may complain of pain in the arm, the back, the shoulder blades, the neck and even the teeth! More than once a patient has visited the dentist as their first port of call!
Because the artery is narrowed rather than blocked, when the work rate of the heart settles, e.g. after exertion, the pain goes away again. These attacks are called angina.
What is a heart attack?
A heart attack is like an attack of angina which doesn’t go away, and the reason the pain doesn’t go away is that the blood vessel has actually become blocked rather than just narrowed. As a result, all the muscle downstream of the blockage gets starved of oxygen, and a heart attack results, where part of the heart muscle is irreversibly damaged.
The reason blood vessels get blocked rather than just narrowed takes us back to the process of atherosclerosis we discussed earlier. The atherosclerotic plaque in the coronary artery is a dynamic rather than just a stable phenomenon. The surface of the plaque may rupture if the plaque itself is very full of fatty deposits. When a plaque ruptures, components of the bloodstream stick to it and a clot forms. This attempted healing process paradoxically blocks the blood vessel causing a heart attack.
A heart attack is much more important than angina because if a patient suffers a large heart attack, a significant part of the heart muscle stops working, and the body has to make do with “running on two cylinders”. This means that patients get tired easily and have limited exercise capacity. In severe cases they may develop heart failure.
Prevention
Prevention is better than cure, they say, and of course that’s right. The problem with ischaemic heart disease is that it is hidden away, so looking for early signs is difficult. We have to rely on what are called “risk factors” and try to weigh them up. The main risk factors are family history, cholesterol, high blood pressure, smoking and diabetes. Diet and lifestyle are important too.
- You can’t do much about your family history, but if you have close relatives who have had angina or a heart attack under the age of 60, it pays to keep your other risk factors under control.
- Cholesterol is crucial, but it’s only in the last 30 years that it has really become clear how crucial. Patients who have had a heart attack or angina are now routinely given medication to reduce cholesterol (whatever the actual level is) because this will limit the risk of any further events. Even patients who have not had angina or a heart attack benefit from cholesterol lowering medication if they have any other risk factors.
- Blood pressure is important too, and, annoyingly, high blood pressure very rarely causes symptoms, so the only way you know about it is to have a measurement done. If you do have high blood pressure, lower salt diet, regular exercise and weight loss are all helpful, but most patients also need medication to get the readings down. Lowering blood pressure also makes a big difference to your chance of having a stroke.
- Sometimes we think that everyone knows about smoking and the risks of heart disease, but it’s not true, or if it is, many patients choose to ignore the facts, even after a heart attack. Stopping smoking is the single biggest modifiable risk factor there is. Smoking makes the blood sticky, so if you have any narrowed arteries in your heart or brain, you are more likely to have a heart attack or stroke.
- Diet has been increasingly recognised as important too. It is clear that patients who have a high saturated fat intake (cheese, diary products, red meat) have a higher rate of ischaemic heart disease. The best diet includes plenty of vegetables, fruit, fish, nuts and a glass of red wine (may take some getting used to with the fish).
- Exercise makes a big difference. Not only does it improve mental wellbeing and general energy levels, but it also reduces your risk of heart attack or stroke. We are not talking ultra-marathon running here, just gentle regular exercise 3 times a week - walking, cycling and swimming are all excellent forms of graded exercise to help reduce your risk of a heart attack.
Heart attacks and stroke remain a huge problem. Young men and women are frequently cut down in their prime by these killers. Increasing awareness of the risk factors and what can be done to modify them has a huge role to play in reducing the disease burden from these malevolent stalkers.
About the author
David Hildick-Smith, MD, FRCP, Consultant Cardiologist, is based at the Royal Sussex County Hospital, Brighton, and the Nuffield Hospitals in Brighton and Haywards Heath. He is Director of the Cardiac Research Unit, author of over 100 peer-reviewed articles and principal investigator for the UK in 6 current randomised clinical trials. His interests include General Cardiology, Echocardiography, Coronary Stenting and Valve implantation.
Copyright YourDoc Medical Ltd 2011. All rights reserved.
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