What occurs during the QRS-complex of the ECG?

The QRS complex of the electrocardiogram (ECG) represents the electrical activity associated with the depolarization of the ventricles. When the ventricles depolarize, this electrical event causes them to contract, which is essential for pumping blood to the lungs and the rest of the body.

During this phase of the cardiac cycle, the electrical impulse travels through the bundle of His and Purkinje fibers after originating from the atrioventricular (AV) node, ultimately triggering ventricular contraction. This complex is crucial in evaluating the heart's electrical conduction system and overall cardiac health, as abnormalities in the QRS complex can indicate various cardiac issues, such as ventricular hypertrophy or conduction block.

Understanding this process is fundamental for assessing cardiac function and recognizing pathological conditions where normal depolarization may be impeded or altered.