@OeKc05 – It doesn't stand for echocardiogram. ECG and EKG are the same thing, and they both stand for electrocardiogram.
An echocardiogram takes a picture of the heart, but an electrocardiogram tells the doctor about the heart's electrical issues. Someone with an irregular heartbeat or who believes he or she may have had a heart attack has an electrocardiogram for diagnosis.
I was taking part in a clinical trial a few years ago, and I had to have an electrocardiogram several times during the trial. It was quick and painless. The electrodes on me hooked to a machine that printed out my heartbeat in wavy lines on paper.