The examination is painless and usually takes less than 15 minutes. Typically, there are two expenses connected with an EKG: the operation itself and the cost of the readout analysis. The average cost of an EKG is $150-200. An EKG measures the electrical activity of your heart by using small electrodes attached to your skin. These electrodes record the movement of muscle fibers in your chest as well as the contraction of your heart muscle. The EKG machine also displays a graph of these measurements on its screen. Your doctor will study this graph to see if you have any abnormalities with your heart rhythm (arrhythmias). Abnormalities of the heart's electrical system can lead to serious problems if left untreated. For this reason, your doctor will want to examine your EKG regularly during your visit or hospital stay. He or she may ask you questions about your symptoms and perform other tests before giving you a clear picture of what is going on with your heart. The most common cause of abnormal EKGs is some type of problem with the conductivity of your blood cells. This can be due to excessive amounts of white blood cells, red blood cells, or platelets. A bone marrow test can help your doctor identify the source of the problem.