What does the heart sound S2 represent?

The heart sound S2, commonly referred to as the "dub" sound, is primarily associated with the closing of the aortic and pulmonary valves. This sound occurs at the end of ventricular systole when the ventricles have contracted and are ejecting blood into the aorta and pulmonary artery. When the pressure in the ventricles decreases below that of the aorta and pulmonary artery, the aortic and pulmonary valves close to prevent backflow of blood.

S2 typically marks the transition from systole to diastole, indicating that the heart chambers are relaxing and preparing to fill with blood again. Understanding this concept is crucial in the context of cardiac physiology, as it helps in evaluating heart function during assessments and can indicate underlying cardiovascular issues if there are abnormal sounds associated with S2.

Recognizing the significance of S2 in the cardiac cycle is essential for accurate interpretation of heart sounds during a physical examination and contributes to the overall assessment of a patient’s cardiac health.