Which part of the ECG strip represents ventricular contraction?

The QRS complex on an ECG strip is crucial because it directly represents the electrical depolarization of the ventricles, leading to ventricular contraction. This part of the ECG demonstrates the rapid spread of electrical impulses through the ventricles, which causes them to contract and pump blood to the lungs and the rest of the body.

When evaluating the ECG waveform, the QRS complex is characterized by its sharp, spiked appearance, indicating the powerful electrical forces at play as the ventricles contract. This contraction follows the brief period of atrial depolarization, which is represented by the P wave, and occurs just before the T wave, which signifies ventricular repolarization.

While the QT interval encompasses both depolarization and repolarization of the ventricles, and the ST segment indicates the period following the QRS complex when the ventricles are in a plateau phase, neither specifically highlights the contraction of the ventricles. The T wave represents the repolarization phase and thus occurs after the contraction has taken place. Therefore, understanding the role of the QRS complex is vital for interpreting the contractile activity of the heart as shown on an ECG strip.