An Electrocardiogram (ECG) is a diagnostic test that measures the electrical activity of the heart. Every heartbeat starts with an electrical wave that travels through the heart, causing the heart muscles to squeeze and pump blood towards the other parts of the body.
ECGs from healthy hearts have a characteristic shape and rhythm. An ECG test gives important information about:
- Abnormalities in the heart rate and rhythm
- Damage from previous a heart attack
- Anatomical changes of the heart.
An ECG test is helpful for the diagnosis of various heart conditions such as:
- Arrhythmia – abnormal heart rhythm (too fast, too slow, or irregular)
- Cardiomyopathy – structural abnormalities of the heart such as enlarged heart chambers
- Hypertrophy – thickening of the heart muscles
- Myocardial ischemia – poor blood flow to the heart muscle from blockages of the heart arteries
- Myocardial infarction – ongoing heart attack or previous heart attack
- Pericarditis – inflammation of the sac covering the heart
In addition, ECGs are done as a follow up to certain treatments for heart diseases e.g. pacemaker.
Your cardiologist may recommend an ECG if you show symptoms of:
- Chest pain
- Shortness of breath
- Palpitations (fast or irregular heartbeat)
- Dizziness, light-headedness or fainting
- Weakness or fatigue
An ECG is recommended for those with cardiovascular risk factors such as:
- High blood pressure
- High blood cholesterol
- High blood sugar/ diabetes
- Family history of heart diseases/ heart attacks
- Family history of sudden cardiac death
- Smoking, obesity and inactive lifestyle
An ECG is sometimes advised for heart screening, in preparation for surgery, and before embarking on a new exercise programme.
An ECG is done as a follow up to certain treatments for heart diseases, e.g. following treatment of heart attack, after angioplasty or heart surgery, treatment of heart arrhythmia, and implantation of a pacemaker.
An ECG does not show whether you have definite blockages in the coronary arteries, nor does it predict your risk of heart attacks. It may detect signs suggestive of blocked arteries in your heart, but it is not in itself conclusive.
If your ECG shows abnormalities that suggest heart artery blockages, your doctor may recommend other tests to further investigate the condition. These tests may include an echocardiogram, a CT scan or a coronary angiogram, depending on your condition.
Before the ECG test:
- Your doctor, nurse, or ECG technician will explain how the test will proceed and answer any questions or concerns you may have. As the electrode patch needs to stick closely to the skin, the staff may have to shave off small patches of hair.
- You will be asked to remove any jewellery, especially those around your chest, as well as any clothing from the waist up. After which, you will be asked to either change into a gown or be covered with a sheet.
- You will be asked to lie flat on a bed. Throughout the test, you will have to lie still and not talk to avoid interfering with the results. The test will take less than 5 minutes.
During the ECG test:
- Electrodes will be placed on your chest, arms, and legs. The bottom of these electrodes are sticky and gel-like that feels like pain-relieving patches.
- Next, the ECG leads (wires) are attached to the electrodes.
- The ECG machine will detect your heart’s electrical activity and print it out as waves.
- Once the recording is completed, the staff will disconnect the wires and remove the electrodes. There might be slight discomfort when the sticky electrodes are removed but it should not feel any much worse than taking off a bandage.
There is no special after-care for an ECG test. Unless the doctor tells you otherwise, you should be able to go home and be back to normal activities right after the test is done.
You should be able to discuss your results with the doctor on the same day as your ECG testing. However, if your ECG is for screening purposes and the results do not show any significant findings that require immediate attention, you may be asked to come back another day to discuss the results.
If your doctor suspects certain conditions, he may recommend further tests to confirm the diagnosis. Depending on your condition, your doctor may also recommend that you make changes in your diet and lifestyle.
Your doctor will keep your ECG reading on file so that they can compare them to tests you get in the future.
It really depends on the type of findings on the ECG. An ECG is accurate in diagnosing certain conditions such as arrhythmias (heart rhythm problems) and a heart attack. Other conditions may require further tests following an ECG to confirm the diagnosis.
Some heart conditions do not result in any changes on the ECG. In other cases, an abnormal ECG result does not necessarily mean that you definitely have heart disease. Depending on your overall condition, your doctor will be able to advise you whether you need further tests.
The standard ECG test is known as a resting ECG. Other types of ECG tests include:
- Ambulatory ECG (or Holter) – you will wear a small portable ECG device for at least 24 hours, sometimes for several days. You are free to move around normally while the device is attached. Your heart rhythm is captured continuously during that time.
- Exercise Stress ECG – this test involves recording your ECG as you exercise on a treadmill machine. It gives a good assessment of how your heart performs during exercise stress.
Does an ECG test hurt?
The ECG is a safe procedure with no pain or risk involved. It does not send electric current to the body. Some people may be allergic or sensitive to the electrodes and may develop a slight rash from the patches.
Is an ECG test harmful?
No. ECG is a non-invasive test. The machine simply records the electrical activity of your heart without transmitting any electricity of its own.
Does being nervous affect the ECG reading?
No. ECG readings are reliable and not affected by anxiety. If there are tremors causing artifacts on the ECG readings, your doctor will know how to differentiate them.
What should I tell my doctor before an Electrocardiogram?
You should inform your doctor of the following:
- Any preexisting medical conditions you have
- Any medications or supplements you are taking
- If you have a pacemaker
- If you had previous surgeries or treatments on your heart
An electrocardiogram is a standard, simple and non-invasive test to help your doctor get a better idea of how your heart is doing. Hopefully, this article has helped guide you through what to expect for an ECG test. Should you have any concerns or queries, do not hesitate to ask your doctor so that he may address them for you.
