What does the QRS complex represent in an ECG?

The QRS complex is a crucial component of an electrocardiogram (ECG) that reflects the electrical activity associated with the depolarization of the ventricles. When the heart receives an electrical signal from the atrioventricular (AV) node, it spreads rapidly through the ventricles, causing them to contract and pump blood. This rapid depolarization is what gives the QRS complex its shape on the ECG waveform.

The QRS complex appears as a series of sharp peaks and troughs, and its duration and morphology can provide important clinical information about the heart's electrical conduction system and overall function. A normal QRS complex typically lasts between 80 and 100 milliseconds. Abnormalities in the QRS complex can indicate issues such as bundle branch block, ventricular hypertrophy, or other cardiac conditions.

Understanding that the QRS complex corresponds specifically to ventricular depolarization is foundational in interpreting ECGs and diagnosing various cardiac conditions effectively.