Electrocardiogram — Definition

Definition

Imagine your heart as a highly organized electrical pump. Every beat is initiated by a tiny electrical impulse, which then spreads throughout the heart muscle, causing it to contract and pump blood. An Electrocardiogram, or ECG (sometimes called EKG, from the German 'Elektrokardiogramm'), is essentially a 'snapshot' or a 'movie' of these electrical signals as they travel through your heart.

It's a completely non-invasive test, meaning nothing goes inside your body. Small sticky patches called electrodes are placed on your chest, arms, and legs. These electrodes are like tiny microphones that pick up the faint electrical signals generated by your heart.

These signals are then amplified and displayed as a wavy line on a screen or printed on a special grid paper.

Think of it this way: when a muscle cell in your heart gets an electrical signal, it 'depolarizes' (becomes electrically active) and then 'repolarizes' (resets itself). These changes in electrical potential create tiny currents that can be detected on the skin surface.

The ECG machine records these changes over time, showing a characteristic pattern of waves and segments. Each wave on the ECG tracing corresponds to a specific electrical event in the heart. For instance, one wave shows the electrical activation of the atria (the upper chambers), another shows the activation of the ventricles (the lower, stronger pumping chambers), and yet another shows the ventricles resetting themselves.

By analyzing the shape, size, and timing of these waves, doctors can understand if the heart is beating at a normal rate, if its rhythm is regular, and if there are any signs of damage or disease in the heart muscle or its electrical wiring.

It's a fundamental tool for diagnosing conditions like irregular heartbeats (arrhythmias), heart attacks, or even problems with the heart's size or structure.