Medical assistants are medically trained professionals who typically work in a doctor's office providing help to the physician, nurses and patients. Assisting with medical treatments, obtaining vital signs and performing tests are part of what medical assistants do during their shift. They are taught how to use equipment such as a heart monitor, blood pressure cuff and angiocatheter. An EKG is a test that allows a patient's heart rhythm to be seen and interpreted. A heart monitor or EKG machine is used to perform an EKG.