An electrocardiogram — also called ECG or EKG — is often done in a health care provider's office, a clinic, or a hospital room. An electrocardiogram records the electrical signals in the heart. It's a common and painless test used to quickly detect heart problems and monitor the heart's health. ECG machines are standard equipment in operating rooms and ambulances. Some personal devices, such as smartwatches, offer ECG monitoring.

Source: Mayo Clinic