Electrocardiogram

An electrocardiogram (ECG or EKG, abbreviated from the German Elektrokardiogramm) is a graphic produced by an electrocardiograph, which records the electrical voltage in the heart in the form of a continuous strip graph. It is the prime tool in cardiac electrophysiology, and has a prime function in screening and diagnosis of cardiovascular diseases.

Uses
12-lead electrocardiogram (ECG) with ST-segment elevation in leads II, III and aVF, suggestive of an inferior acute myocardial infarction (AMI).The ECG has a wide array of uses:

Determine whether the heart is performing normally or suffering from abnormalities (eg. extra or skipped heartbeats - cardiac arrhythmia).
May indicate acute or previous damage to heart muscle (heart attack) or ischaemia of heart muscle (angina).
Can be used for detecting potassium, calcium, magnesium and other electrolyte disturbances.
Allows the detection of conduction abnormalities (heart blocks and bundle branch blocks).
As a screening tool for ischaemic heart disease during an exercise tolerance test.
Can provide information on the physical condition of the heart (eg: left ventricular hypertrophy, mitral stenosis).
Can suggest non-cardiac disease (e.g. pulmonary embolism, hypothermia)