Electrocardiography (ECG) is the process of recording the electrical activity of the heart over a period of time using electrodes placed on the skin.
Why should I do it ?
The overall goal of performing electrocardiography is to obtain information about the structure and function of the heart. Medical uses for this information are varied and generally relate to having a need for knowledge of the structure and/or function. Some indications for performing electrocardiography include:
- Suspected myocardial infarction (heart attack) or new chest pain
- Suspected pulmonary embolism or new shortness of breath
- A third heart sound, fourth heart sound, a cardiac murmur  or other findings to suggest structural heart disease
- Perceived cardiac dysrhythmias  either by pulse or palpitations
- Monitoring of known cardiac dysrhythmias
- Fainting or collapse 
- Seizures 
- Monitoring the effects of a heart medication (e.g., drug-induced QT prolongation)
- Assessing severity of electrolyte abnormalities, such as hyperkalemia
- Hypertrophic cardiomyopathy screening in adolescents as part of a sports physical out of concern for sudden cardiac death (varies by country)
- Perioperative monitoring in which any form of anesthesia is involved (e.g., monitored anesthesia care, general anesthesia); typically, both intraoperative and postoperative.
- As a part of a pre-operative assessment some time before a surgical procedure (especially for those with known cardiovascular disease or who are undergoing invasive or cardiac, vascular or pulmonary procedures, or who will receive general anesthesia)