Angina, unstable - What is it?
In this section
Unstable angina is the pain you feel in your chest when your heart is not getting enough oxygen. It may be a worsening of the chest pain you were already getting with a condition called stable angina. Or it may be a brand new chest pain.
Stable angina usually happens only when you are active. It typically stops when you rest for a few minutes and take your angina medicine. But unstable angina can happen even when you are resting, and it may not go away when you take your angina medicine. The pain is usually worse than in stable angina, and it is likely to go on for at least 20 minutes.[1]
Doctors often think of unstable angina as the middle step between stable angina and a heart attack. The lack of oxygen is worse than in stable angina. But it isn't as bad as in a heart attack. A heart attack can cause permanent damage to your heart.
If you get unstable angina, it is an emergency. You need treatment straight away. It's important to dial 999 and get emergency medical help.
In the longer term, taking medicine and changing how you live can help you have fewer and milder attacks. It can also lower your risk of having a heart attack.
Key points for people with unstable angina
- Unstable angina usually happens when the arteries in the heart get narrow from a build-up of fat. Doctors call this coronary artery disease.
- People often describe unstable angina as a discomfort, an ache or pain, or a burning feeling or heavy pressure. It usually lasts at least 20 minutes.
- You are most likely to get these symptoms in your chest. But you can also get pain and discomfort in your back, arm, jaw or throat.
- This can start without any warning, even if you are resting.
- Your doctor should check out any new chest discomfort or pain, even if it goes away.
- If it is unstable angina, you need to go to hospital straight away for treatment. This is to lower your risk of having a heart attack.
- You will also need to take other medicines, some for life, to lower your risk of having more attacks of unstable angina.
- Making some changes in your daily life will also lower these risks. If you smoke, now is the time to stop.
Your heart and how it works
To understand what happens when you have unstable angina, it helps to know something about your heart and how it works.[2]
Your heart is in the middle of your chest. It is a muscle shaped like a fist. It works automatically, so you don't have to think about making it beat.
Your heart works like a pump. Every time it beats, it pushes blood around your body.
Blood carries oxygen and food (nutrients) to your cells. The cells in your body will die if they don't get a constant supply of both. For more, see How your heart moves blood around your body.
Your heart works harder, and for longer, than any other organ in your body. If your heart stops working, every other part of your body will die within minutes.
The parts of your heart
Your heart has thick, muscular walls. It's divided into two sides, right and left. Each side has an upper part and a lower part. Doctors call these chambers.
The two chambers on the right side of your heart pump blood to your lungs, where the blood picks up oxygen. Blood then returns to the two chambers on the left side. They pump the blood to the rest of your body, taking oxygen and food to your cells.
The two upper chambers of your heart are called the right atrium and the left atrium. The two lower chambers are larger. They are called the right ventricle and the left ventricle.
For more, see What happens when your heart beats.
How your heart gets its own supply of blood
To do its job, your heart needs its own supply of blood. The blood carries oxygen to your heart's cells, so that it can do its work.
Your heart gets this blood from your coronary arteries. They supply the heart's muscular wall with blood that is rich in oxygen.
Your left coronary artery has two main branches.
- One is called the left anterior descending artery (or LAD for short). It supplies most of the blood to your left ventricle, the part of your heart that pumps blood out to your body. This job makes this artery very important to your health.
- The other one is called the left circumflex artery.
Your right coronary artery is smaller. Its branches carry blood to the back of your heart. These arteries split into a network of smaller vessels that take blood deeper into your heart muscle. For more, see How blood moves through your heart.
What happens in unstable angina
Most people get unstable angina because of a condition called coronary artery disease. This is when clumps of fat (called plaques) build up on the smooth lining of a coronary artery. Over time, they make the artery narrower, stiffer and rougher.
This is called atherosclerosis. It's very common. It can happen in arteries anywhere in your body. If you have atherosclerosis in your coronary arteries, you have coronary artery disease. You may hear doctors call this ischaemic heart disease or coronary heart disease.
Here is what happens in unstable angina.
- A plaque in one of your coronary arteries breaks open and tears.
- A blood clot forms over the tear to try to patch it up, just like a scab forms on your skin if you cut yourself.[1] Doctors call this clot a thrombus.
- The clot partly blocks the artery. Then there isn't enough blood getting through to your heart.
- Not enough blood means not enough oxygen. This is what causes the bad pain and discomfort of unstable angina.
- The clot can get bigger. If the clot totally blocks off the artery and there isn't any oxygen getting to your heart, it's called a heart attack. This can permanently damage your heart. For more, see Heart attacks.
Sometimes, because the symptoms are the same, it can be hard for doctors to tell if someone has unstable angina or a type of heart attack. They can find out by doing certain tests. For more, see How do doctors diagnose unstable angina?
You may hear doctors use the words acute coronary syndrome (ACS for short). This is a general term. It covers both unstable angina and some types of mild heart attack. For more, see Acute coronary syndrome.
We have looked at unstable angina caused by coronary artery disease. But some people have angina caused by another condition that stops their heart getting enough oxygen. For more, see Other causes of angina. If your angina is caused by something else, talk to your doctor about how it should be treated.
There are different types of angina too. On these pages, we look at unstable angina. For more on the others, see Other types of angina.
Why me?
We don't know exactly why fatty clumps (called plaques) build up in some people's arteries and cause angina. And we don't know why some people's angina is stable while other people's angina is unstable. But we do know that some things make it more likely you will get coronary artery disease and angina. Doctors call these things risk factors. Having a risk factor doesn't mean you'll get angina for sure. It just means you are more likely to get it than someone who doesn't have that risk factor.
The risk factors for angina are the same as the risk factors for heart disease. We've listed the main ones below.[3]
- Being male
- Being middle-aged or older
- Having heart attacks or coronary disease run in your family
- Smoking
- Being overweight or obese
- Having high cholesterol
- Having high blood pressure
- Having diabetes.
The more risk factors you have, the more likely you are to get unstable angina. But you and your doctor can work to make your risk factors less dangerous. This can reduce your chance of getting an attack of unstable angina again or of having a heart attack.
You can't do anything about some risk factors, like conditions that run in your family or getting older. But you can do something about others, like smoking. If you smoke, now is the time to stop. And eating better and exercising will both help.
Being under stress may affect some risk factors. For example, if you're stressed, you might eat or smoke more than usual. We don't know if stress by itself makes you more likely to get angina.[2]
For more on steps you can take to stay as healthy as possible, see Unstable angina: what you can do to help yourself.
You can also get good treatments for some of the things that put you at risk for getting angina. For more, see our articles on these topics:
References
- Grech ED, Ramsdale DR. Acute coronary syndrome: unstable angina and infarction non-ST segment elevation myocardial. BMJ. 2003; 326; 1259-1261.
- Martini FH. The heart. In: Ober WC, Garrison CW, Welch K, et al. Fundamentals of anatomy and physiology 5th edition. Prentice Hall, Upper Saddle River, U.S.A.; 2001.
- Natarajan M. Angina (unstable). October 2005. BMJ Clinical Evidence [online]. Available at http://www.clinicalevidence.com (accessed on 5 June 2007).
Glossary
- heart attack
- Doctors call a heart attack an acute myocardial infarction (or acute MI). This is the name for the damage that occurs to the heart muscle if it isn't getting enough blood and oxygen because a branch of the is blocked. During a heart attack, you may have pain or heaviness over your chest, and pain, numbness or tingling in your jaw and left arm.
- arteries
- Arteries are the blood vessels that take blood that is rich in oxygen and food away from your heart. The arteries carry this blood to all the tissues in your body.
- atherosclerosis
- Atherosclerosis s also called 'hardening of the arteries'. It happens when fatty material sticks to the inner wall of the arteries. Over time, cholesterol, fats and other things in the blood stick to the same area and the artery wall becomes thick and narrow, making it progressively more difficult for blood to flow through the affected vessels.
- obesity
- If your body stores more energy than you need, this can make you overweight. The excess energy is stored in your fat cells. If your weight goes above a certain level, doctors call this obesity. Obesity is considered a medical condition. The excess weight can be a strain on your bones and joints. And if you are obese, you're more likely to get other diseases. Doctors have developed a scale for telling how much excess weight you have. This measure, called the body mass index (BMI), depends on your height.
- high cholesterol
- The term high cholesterol is a bit misleading. High levels of are actually good for you. But if you've been told that you have high cholesterol it means that your total cholesterol level is 5 or higher or your is 3 or higher or both. Having high cholesterol can make it more likely that you'll get certain diseases in your heart and arteries.
- high blood pressure
- Your is considered to be high when it is above the accepted normal range. The usual limit for normal blood pressure is 140/90. If either the first (systolic) number is above 140 or the lower (diastolic) number is above 90, a person is considered to have high blood pressure. Doctors sometimes call high blood pressure 'hypertension'.
- diabetes
- Diabetes is a condition that causes too much sugar (glucose) to circulate in the blood. It happens when the body stops making a called (type 1 diabetes) or when insulin stops working (type 2 diabetes).
© BMJ Publishing Group Limited ("BMJ Group") 2007. All rights reserved
This information does not replace medical advice. If you are concerned you might have a medical problem please ask your Boots pharmacy team in your local Boots store, or see your doctor.
