Electrocardiogram (ECG)
What is an Electrocardiogram (ECG)?
An ECG test records the electrical activity of the heart. It can inform doctors about heart rate, rhythm (such as an arrhythmia), conduction health of tissues, thickening of heart muscle, size of chambers, inflammation, ischaemia (state of oxygen deprivation), heart attack (sudden blockage of blood supply to part of heart muscle), and a host of other important parameters.
An ECG works by tracking the electrical impulses (or “waves”) travelling through the heart with each heartbeat. This impulse starts in the right atrium (right upper chamber of the heart), generated by the heart’s own independent “Pacemaker” and then travels throughout the heart tissue through a specialised highly sophisticated system of cells – just like “electrical wires”. This electrical current causes the heart muscle to contract, squeeze and pump blood through the heart.
A normal heartbeat on an ECG shows different waves that represent the heart’s electrical activity. The first wave, called the “P wave,” happens when the upper chambers (atria) send an electrical signal. After a brief pause, the signal reaches the lower chambers (ventricles), shown by the “QRS complex.” This pause allows the upper chambers to push blood into the lower chambers before they contract to pump blood out. The last wave, the “T wave,” shows the ventricles returning to their resting state. This cycle repeats with each heartbeat, occurring around 100,000 times per day in a healthy person.
Preparing for your visit
- For preparation, your skin will be cleaned with alcohol wipes and gently prepared with skin prep tape.
- Please note that the patients will be required to remove their shirt above the waist for the procedure and you will be provided with a disposable gown.
- For preparation, some hair may need to be shaved off to improve the electrical signals.
- Electrodes are placed on your chest with a sticky, but easy-to-remove, adhesive. Lead wires from the ECG machine are connected to the electrodes.
- You’ll be asked to lie still and breathe normally. Any movement can affect the reading.
- Avoid wearing lotions or oils as they can interfere with electrode adhesion.
- Avoid caffeine or stimulants for a few hours before the test as they can affect heart rhythm.
- Please let the staff know if you have had any allergic reactions to the electrode adhesives previously.
Electrocardiogram (ECG) - How the Test is Done
An electrocardiogram (ECG) is a simple test that traces your heart’s electrical activity using an ECG machine. No special preparation is needed before you arrive.
You’ll be taken to a dedicated room where our staff place electrode stickers across your chest and on your arms. In some cases a small amount of chest hair may need to be shaved so the electrodes pick up a clear signal. The electrodes are connected to the ECG machine by wires and the recording begins.
The whole process is quick, usually taking no longer than 10 minutes. Once a satisfactory tracing is recorded, the wires and stickers are removed and your chest is cleaned off before you leave, and a cardiologist reviews and reports the tracing, with the final report sent to your referring doctor.
Frequently Asked Questions
An ECG can show your heart rate and rhythm, pick up irregular rhythms (arrhythmias), and reveal signs of reduced blood flow to the heart muscle, which can be linked to conditions such as angina as well as evidence of a previous heart attack or a thickened heart muscle. Your cardiologist interprets the tracing alongside your symptoms and history.
Several factors can affect ECG readings, including movement during the test, lotions or oils on the skin, poor electrode contact, and caffeine or other stimulants consumed before the appointment. Following your preparation instructions and remaining still during the test helps ensure accurate results.
A standard ECG is very quick, usually completed in under 10 minutes.
The procedure is the same for everyone. To place the electrodes correctly, you will be asked to remove clothing above the waist and wear a disposable gown. Some electrodes may be placed beneath or around the breast tissue to obtain an accurate reading. Your privacy and comfort will be maintained throughout the test.
A standard ECG is a safe, non-invasive test with no known risks. Some people may experience mild skin irritation from the adhesive electrodes, but this is uncommon and usually resolves quickly.
Other Cardiology Services
24hr Holter
Monitor
A 24-hour Holter monitor service provides continuous heart rhythm monitoring to detect irregularities or assess ongoing conditions.
Echocardiogram
(TTE)
An echocardiogram is an ultrasound that assesses heart structure and function in real time, and is valuable for diagnosing conditions.
Stress
Echocardiogram
A stress echocardiogram evaluates heart function and blood flow during exercise to assess cardiovascular health under exertion.
