Which wave on an EKG represents ventricular systole?

The QRS complex on an electrocardiogram (EKG) represents ventricular systole, which is the phase of the cardiac cycle when the ventricles contract. This event is crucial for pumping blood into the pulmonary and systemic circulation. The QRS complex reflects the depolarization of the ventricles—this electrical activity triggers the contraction of the ventricular myocardium.

During this phase, the electrical impulse, which originates from the sinoatrial node and travels through the atrioventricular node, is carried swiftly through the bundle branches and Purkinje fibers, leading to a coordinated contraction. The rapid depolarization and subsequent contraction of the ventricles are essential for effective blood circulation, making the QRS complex a key indicator of this phase.

The other components of the EKG serve different functions in the cardiac cycle. The P-wave represents atrial depolarization, while the T-wave reflects ventricular repolarization, which occurs after the contraction. The RR interval, defined as the time between two successive R-wave peaks, indicates the heart rate but does not directly represent any specific phase of ventricular contraction. Therefore, the QRS complex is the accurate choice for identifying ventricular systole on an EKG.