ELI5: Explain Like I'm 5

Electrocardiography

Electrocardiography (ECG) is a special type of test that allows doctors to measure the electrical signals in your heart. By placing small patches called electrodes on your chest, arms, and legs, your doctor can detect the tiny electrical changes that happen when your heart beats. The electrical signal shows up on a screen which looks like a line going up and down. It is like a picture that shows how your heart is working.