An ecg test is a test that checks for issues with the electrical activity of the heart during expansion and contraction. The ekg test machine is the machine that records the activity taking place and displays in the form of waves. It’s common for doctors to look at the dips and spikes on readings to be used as a way to interpret the health of the heart and the body overall. If the beating of the heart is not within the safe range, then the patient would be suffering from arrhythmia.