An electrocardiogram (ECG) is a medical test that detects abnormalities of the heart (heart) by measuring the electrical activity generated by the heart as it shrinks. The machine that records the patient’s ECG is called an electrocardiograph.

The electrocardiograph records the electrical activity of the heart muscle and displays this data in the form of a trace on a screen or paper. This data is interpreted by a physician.

The ECG of healthy hearts has a specific shape. Any irregularity in the heart rhythm or damage to the heart muscle can alter the electrical activity of the heart causing the ECG to change shape.

A doctor may recommend the ECG for those who are at risk of heart disease because of a family history of heart disease, or because they smoke, are overweight, or have diabetes, high cholesterol, or high blood pressure.