The electrocardiogram is commonly used to detect abnormal heart rhythms and to investigate the cause of chest pains
What is an electrocardiogram?
An electrocardiogram (ECG) records the electrical activity of the heart. The heart produces tiny electrical impulses which spread through the heart muscle to make the heart contract. An ECG is performed to help find the cause of symptoms such as palpitations or chest pain. Sometimes it is done as part of routine tests – for example, before you have an operation. The ECG test is painless and harmless.
How is it done?
Small metal electrodes are stuck on to your arms, legs and chest. Wires from the electrodes are connected to the ECG machine. The machine detects and amplifies the electrical impulses that occur at each heartbeat and records them on to a paper or computer. A few heartbeats are recorded from different sets of electrodes. The test takes about five minutes to do.
What does an electrocardiogram show?
Various heart disorders produce abnormal ECG patterns. The heart disorders that can be detected include:
- Abnormal heart rhythms – Fast, slow, or irregular.
- A previous heart attack
- Heart muscle thickening and enlargement.
Limitations of the electrocardiogram
An ECG is a simple and valuable test. Sometimes it can definitely diagnose a heart problem. However, a normal ECG does not rule out serious heart disease particularly if the symptoms are intermittent and not present during the test. In this instances a longer period of ECG recording my be helpful. In addition, not all heart attacks nor angina can be reliably detected by ECG.