ABSTRACT
The electrocardiogram (ECG) records the electrical activity (depolarization and repolarization) of cardiac muscle from the body surface and provides information on heart rate, rhythm, and intracardiac conduction. ECG findings may also suggest the presence of specific chamber enlargement, myocardial disease, ischemia, pericardial disease, certain electrolyte imbalances, and some drug toxicities. However, the ECG does not record cardiac mechanical activity; therefore, the ECG by itself cannot be used to diagnose congestive heart failure, assess the strength (or even presence) of cardiac contractions, or predict whether the patient will survive anesthetic or surgical procedures.
