An EKG test is used to check the electrical activity of a patient's heart. These are often done in order to monitor how medication is working for a patient, to check the rhythm of the heart and, in some cases, to check if medical heart equipment is working correctly.
EKG or ECG, stands for electrocardiogram, which is attached to a patient's body with electrodes. Those electrodes monitor the pulses of the heart and print out the waves that the rhythms make on a paper that the doctor can visually review for patterns or irregularities. These let the doctor make adjustment to a patient's care as needed to keep his heart regulated.