This display indicates the overall rhythm of the heart
, and weaknesses in different parts of the heart
muscle. It is the best way to measure and diagnose abnormal rhythms of the heart, particularly abnormal rhythms caused by damage to the conductive tissue that carries electrical signals, or abnormal rhythms caused by levels of salts, such as potassium, that are too high or low. In myocardial infarction (MI), the ECG can identify damaged heart muscle.