The electrocardiogram (ECG or EKG) is a diagnostic tool that measures and records the electrical activity of the heart in exquisite detail. Interpretation of these details allows diagnosis of a wide range of heart conditions. These conditions can vary from minor to life threatening. The term electrocardiogram was introduced by Willem Einthoven in 1893. The process of performing an ECG involves attaching a series of electrodes to the patient's chest and limbs (usually with the patient lying down), and printing a recording on the ECG machine for interpretation by the specialist. It takes approximately 5 minutes to record a diagnostic ECG.