electrocardiography

thumb|Use of monitoring (medicine)|real time monitoring of the heart in an [[intensive care unit in a German hospital (2015), the monitoring screen above the patient displaying an electrocardiogram and various values of parameters of the heart like heart rate and blood pressure]]

Electrocardiography is the process of using an electrocardiograph (a device) to produce an electrocardiogram (a recording, often called an ECG or EKG) that shows a line graph of the heart's electrical activity through repeated cardiac cycles. It is an electrogram of the heart which is a graph of voltage versus time of the electrical activity of the heart using electrodes placed on the skin. These electrodes detect the small electrical changes that are a consequence of cardiac muscle depolarization followed by repolarization during each cardiac cycle (heartbeat). Changes in the normal ECG pattern occur in numerous cardiac abnormalities, including: Cardiac rhythm disturbances, such as atrial fibrillation and ventricular tachycardia; Inadequate coronary artery blood flow, such as myocardial ischemia and myocardial infarction; and electrolyte disturbances, such as hypokalemia.