Electrocardiogram (ECG)

A recording of the heart's electrical activity

Definition

An electrocardiogram (ECG/EKG) is a non-invasive test that records the electrical activity of the heart through electrodes on the skin. It diagnoses arrhythmias, ischemia, infarction, electrolyte imbalances, and structural abnormalities.

ECG Components

P wave: Atrial depolarization.
QRS complex: Ventricular depolarization.
T wave: Ventricular repolarization.
ST segment: Interval between depolarization and repolarization; elevation suggests STEMI, depression suggests ischemia.
U wave: May be seen with hypokalemia.

Key Diagnostic Patterns

Peaked T waves: hyperkalemia. Flat T waves and U waves: hypokalemia. Prolonged QT: risk for torsades de pointes. ST elevation: STEMI. Wide QRS: bundle branch block or V-tach. Irregular rhythm without P waves: atrial fibrillation.

Nursing Considerations

Clean skin, shave if necessary, place electrodes precisely, obtain 12-lead within 10 minutes for chest pain. Identify life-threatening rhythms and notify provider immediately. Continuous telemetry monitoring for high-risk patients.

NCLEX Relevance

Identify V-fib, V-tach, A-fib, PVCs, and recognize STEMI patterns.