What is the heart and how does it work?
The heart is a muscle inside your chest, which pumps blood around your body to your vital organs. It’s a special piece of plumbing, made up of four chambers with pipes into and out of it. Between each chamber, and in each of the tubes, there are valves which control the flow of blood. Your heart receives its own supply of blood full of oxygen, from a few vessels called the coronary arteries. These arteries wrap around your heart and keep it alive.
Why do I need a stress test?
A stress electrocardiogram, also known as a “stress ECG” or “exercise stress test”, is performed to check how well your heart is functioning. A doctor may ask you to get a stress test if you have an abnormal heart rhythm (arrhythmia), chest pain or shortness of breath. It is used to check if you have coronary artery disease or an arrhythmia. If you are receiving treatment for a known heart condition, a stress test can provide information about how well your treatment is working.
What is a stress test, and how is it performed?
An electrocardiogram (ECG) is a non-invasive test used by doctors to look at the electrical messages from your heart. Someone will place 10 sticky patches across your body, on your arms, legs, and chest. Then they will clamp 1 wire onto each of these sticky patches, so you will have 10 wires connecting you to ECG machine. The machine will then pick up the electrical current from your heart as it spreads with each heartbeat.
Before the test starts, you’ll be asked to stay quiet and still for a couple of minutes while the doctor records your heart’s electrical current. The ECG machine will print out a piece of paper with some squiggly lines for your doctor to interpret. Then, the doctor will use the ECG to continuously monitor your heart while you exercise.
You will walk or run on a treadmill for anywhere between 5 to 15 minutes. The speed and incline of the treadmill will increase over time. The test can also be done using a stationary bike, and during the test the speed and resistance of the bike will increase. The aim of the exercise is to make your heart beat faster. If you have chest pain or breathlessness, the test is stopped.
If you can’t exercise for some reason, doctors can give you a drug that makes your heart respond as if you are exercising. Your blood pressure and heart rate will briefly increase. The test is otherwise performed as normal.
When your heart rate is at its fastest, or if you have symptoms like chest pain or shortness of breath, the doctor will ask you to stop exercising and stay still. They will monitor your heart rate and rhythm with the ECG. You will have time to cool down and catch your breath after this, if you need.
How do I need to prepare?
Your doctor will discuss this with you. There are certain medications you might not be able to take before your test (for example, beta-blocker or nitrate medications). They may also want you to avoid caffeine or food before the test.
What will it tell us?
A stress test can tell us if your heart is getting enough oxygen during exercise. Some people may have no symptoms or their heart may function normally at rest, but can have chest pain, trouble breathing or changes in their heart function when they exercise. The electrical signals from your heart change when it isn’t getting enough oxygen, and this is visible on an ECG. This is most often due to coronary artery disease. A stress test can also tell us if exercise triggers an abnormal rhythm in your heart.
What are the risks?
An ECG is non-invasive and has virtually no risk.
However, there are some risks linked to the exercise part of the test. These risks include low blood pressure, an irregular heart rhythm (arrhythmia), chest pain, and rarely, a heart attack. You are at a higher risk of these problems if you have severe heart disease. Your doctor will take these factors into account when deciding whether to give you a stress test. During the test, there will be emergency equipment and staff are trained to deal with these problems if they arise.
Where to from here?
Once your doctor has the results from your stress test, they will discuss the results with you and decide on a treatment plan. You might need further tests like a CT scan of your heart or a coronary angiogram. If you have an abnormal heart rhythm, the options for treatment include medication, or in some cases, a surgical procedure or pacemaker. The options for treatment of coronary artery disease, a past heart attack and other issues often involve exercise and rehabilitation programs, medication and sometimes surgery.