elektrokardiogrammet

Elektrokardiogrammet, in English called the electrocardiogram (ECG or EKG), is a noninvasive diagnostic test that records the heart's electrical activity using electrodes placed on the skin. The tracing reflects the electrical events that trigger heart muscle depolarization and repolarization as the heart beats.

Principle and leads: Electrodes detect voltage differences generated by cardiac activity, and the ECG device compiles these signals into a time‑voltage trace. A standard 12‑lead ECG provides multiperspective information about the heart’s electrical activity, while single‑lead systems are used for continuous monitoring.

Procedure: The patient lies still while several disposable electrodes are attached to the chest and limbs. Recording typically lasts a few minutes, and preparation may involve removing jewelry and noting medications or recent exercise. Artifacts from movement or poor contact can affect the trace.

Clinical uses: ECG is used to diagnose and monitor arrhythmias (such as atrial fibrillation, flutter, ventricular tachycardia), ischemia or infarction, electrolyte disturbances, and conduction abnormalities. It also helps guide treatment, evaluate pacemaker function, and monitor patients during surgery or in emergency settings.

Interpretation and limitations: The ECG trace shows components such as P waves, QRS complexes, and T waves. Clinicians assess intervals (PR, QRS, QT), morphology, and ST‑segment changes. Normal values vary by age and sex, and interpretation depends on clinical context. The test does not assess cardiac structure or function and can be affected by artifacts or lead placement; abnormalities often require additional testing.

Safety: The procedure is safe and noninvasive, with minimal risk; occasional skin irritation from electrodes may occur.