12-Lead Electrocardiogram (ECG or EKG)

Overview What to Expect Our Expertise & Doctors FAQ

What is a 12-lead electrocardiogram (ECG)?

An electrocardiogram or ECG (also known as an EKG) is a test that detects and records the heart’s electrical activity. It is a quick, safe and pain-free procedure.

Based on this activity, a clinician can:

Assess the heart's rhythm and rate
Detect signs of heart disease
Identify potential heart enlargement

Why do you need an electrocardiogram (ECG)?

You may need an ECG if you have symptoms such as:

Chest pain
Dizziness
Heart palpitations
Shortness of breath

Your doctor may order an ECG as part of:

Screening
Before performing surgery
Checking the effects of pacemakers
A check-up after heart surgery

The results allow your doctor to find heart problems including irregular heartbeat (arrhythmia), irregular blood flow to the heart muscle, cardiac birth defects, and heart valve disease.

The results can also allow your doctor to determine if a part of the heart is enlarged or is overworked.

If your symptoms come and go

If your symptoms tend to come and go, you may need remote or continuous ECG monitoring over a longer time period.

The types of monitoring include:

Holter monitor, a portable device that continuously records your heart's electrical activity. You will wear it usually for 24 – 48 hours, but it can be worn longer, for up to 1 – 2 weeks.
Event monitor, a portable device that records for a few minutes at a time only when symptoms occur. You will wear it typically for 30 days.
Implantable loop recorder, a small device implanted under the skin of your chest that allows continuous long-term monitoring of your heartbeat. The implant can be used for up to 3 years.

What can you expect during an electrocardiogram (ECG)?

During an ECG:

You will need to change into a gown for easy access and remove jewellery and other objects that may interfere with the test.
You will be asked to lie flat on a table or bed.
Electrodes will be attached on your chest, arms, and legs. If you have body hair, it may be trimmed or shaved to ensure that the electrodes can stick to the skin.
These electrodes are attached to wires that lead to the ECG machine.
During the test, you will need to lie still and remain silent. The test is painless and takes only a few minutes.
Once the test is completed, the leads and electrodes will be removed.

You will be able to resume your regular activity after the test.

Frequently asked questions

A: EKG stands for elektrokardiographie, the German spelling for electrocardiogram. Both ECG and EKG refer to the same test.

A: They are not the same. An ECG records the electrical activity of the heart. An echocardiogram is an ultrasound scan that uses high-frequency sound waves to create a picture of the heart.

Both tests are important and play a complementary role.

An ECG is a fast and inexpensive test that is useful for screening and picking up any abnormalities in the heart rate and rhythm. If there is an anomaly, an echocardiogram is a useful second test as it provides an internal ‘picture’ of the heart, such as its structure, blood flow, size and shape.

A: An ECG test can diagnose:

Arrhythmia (abnormal heart rhythm)
Congenital heart defects
Damage or changes to the heart muscle
Electrolytes (such as potassium and calcium) imbalances in the blood
Enlargement of the heart
Fluid or swelling of the sac around the heart
Heart attack or poor blood supply to the heart
Myocarditis (heart inflammation)
Past or current heart attack

A: An ECG test takes about 10 minutes in total. This includes the time needed to attach and remove the electrodes.

A: An ECG provides an accurate reading of the heart’s electrical activity, but it does not always lead to an accurate diagnosis all the time. Some heart problems do not show up on an ECG.

However, an ECG is widely used as a mode of screening, as it is fast and inexpensive and can pick up common issues such as heart failure, heart attack and abnormal heart rhythm. It is best used in combination with other tests for greater accuracy.

A: An ECG records the electrical activity of the heart. When the heart beats, an electrical signal is sent through each of the 4 chambers in the heart, causing it to contract and relax in a coordinated way.

The ECG machine records this electrical activity and translates it to a wave-like line. Based on the pattern of the line, your doctor will be able to see how well the heart is working.

Typically, this involves looking at the waves and calculating their distance as well as assessing the shape and direction of the waves. There are a few main waves: P, Q, R, ST and T. Each of these waves represents a specific movement of the heart when it is beating.

A: ECG electrodes are typically placed on specific areas around the heart as well as the arms and legs. This standardised placement helps to ensure an accurate reading each time.

For a 12-Lead ECG, 6 electrodes are placed around the heart and on the chest to obtain electrical data from the front, back and dividing wall of the heart. Two leads each are placed on each arm and leg for a total of 10 electrodes.

A: Electrode placement is important and there is a standardised way to do this. If the electrodes are not placed correctly, it can result in readings that are not accurate.

A: During an ECG test, electrodes will be placed on your chest, arms and legs. For convenience, wear a shirt that can be easily removed and avoid wearing tight pants or stockings. To help the electrodes make good contact with the skin, do not use creams or lotions on the day of the test.

A: The heart rate is calculated by looking at the heart rhythm. In readings with a regular heart rhythm, count how many large squares there are between 1 peak R wave and the next. Divide 300 by the number of large squares.

If the heart rhythm is irregular, count the number of complexes (the 3 waves that occur in rapid succession) that take place over a 10 second strip. Multiply the number of complexes by 6 to get the heart rate.

A: A right-sided ECG may be ordered in cases of a heart attack that involves the right ventricle of the heart.

A: In congestive heart failure, the heart rate and rhythm are affected and this can be picked up by an ECG. There may also be other ECG changes that can indicate heart failure.

A: An ECG is a good diagnostic tool to predict the risk of a heart attack. However, it is best used together with other tests for a more accurate diagnosis.

Why choose Mount Elizabeth Hospitals?

Mount Elizabeth Hospitals are established private hospitals in Singapore for cardiovascular care and treatments such as electrocardiogram (ECG).

You will have access to our accomplished team of cardiologists and cardiothoracic surgeons trusted in the region for their skills and experience in treating a wide spectrum of heart conditions.

Our well-equipped hospital facilities and multidisciplinary medical team ensure that you get the care and focus you deserve on your journey to recovery.

Estimated cost

Private healthcare can be affordable. Use our Hospital Bill Estimator to determine the estimated cost of this procedure. If you have hospital insurance, find out how you can use your insurance.

Our cardiologists

Mount Elizabeth is home to Asia Pacific's largest concentration of heart specialists. Our multidisciplinary team of specialists, nurses and therapists will guide you through your health journey, from diagnosis to treatment.