If a person has chest pain or palpitations , an ECG is helpful in determining if the heart is beating normally. If a person is on medications which may affect the heart or if the patient is on a pacemaker, an ECG can readily determine the immediate effects of changes in activity or medication levels. An ECG may be included as part of a routine examination in patients over 40 years old. There is no reason for healthy people to need annual testing unless they have inherited risks or a medical need. Several different types of electrocardiogram exist.
P waves show that the top of the heart received electrical activity.
QRS waves reflect the electrical activity that causes the heart to contract.