An electrocardiogram (ECG) is a test that detects cardiac (heart) abnormalities by measuring the electrical activity generated by the heart as it contracts.

The electrocardiograph records the electrical activity of the heart muscle and displays this data as a trace on a screen or on paper.

Any irregularity in the heart rhythm or damage to the heart muscle can change the electrical activity of the heart so that the shape of the ECG is changed.

The ECG is a safe procedure with no known risks. It does not send electric current to the body.