What does the QRS complex in an ECG represent?

The QRS complex in an electrocardiogram (ECG) represents ventricular depolarization. This is the electrical event that triggers the contraction of the ventricles, which are the heart's lower chambers. The depolarization occurs as the electrical impulse, originating from the sinoatrial (SA) node in the atria, spreads through the ventricles after passing through the atrioventricular (AV) node.

During this phase, the ventricles are energized, leading to their contraction and the subsequent pumping of blood to the lungs and the rest of the body. This activity is crucial for maintaining an effective circulatory system. The shape and duration of the QRS complex can also provide important clinical information regarding heart function and potential abnormalities in the conduction system.

Understanding the QRS complex is significant in diagnosing various cardiac conditions, including arrhythmias and myocardial infarctions, making this component of the ECG vital for healthcare providers.