According to the National Institutes of Health, an EKG, or electrocardiogram, can show if a patient is having issues with his heart's electrical system. An EKG is a diagnostic tool that doctors can use to determine if a patient is having heart troubles.
Specifically, an EKG can show if a patient has had a heart attack. The test can also show if a part of the heart has a lack of bloodflow, if the patient's heartbeat is too fast or too slow, if the heartbeat is irregular, if the heart muscle is too large, if birth defects are present or if the heart valves are not functioning properly. An EKG test can also tell doctors if a patient's heartbeat is beginning in the right place, states the National Institutes of Health.