HEALTH: ECG (ELECTROCARDIOGRAPHY)
The electrocardiogram shows The electrical activity of the heart in wave form.
The the photo below shows what each wave represent.
P wave represent the period of atria depolarization.
PR segment represent AV delay
QRS represent period of ventricular depolarization.
T wave represent the period of ventricular repolarization.
The straight lines are also called isoelectric line because there are no electric activities.