Progressive Care Nursing Certification (PCCN) Practice Exam

What does the heart sound S1 signify?

1. The beginning of ventricular systole

2. The beginning of ventricular diastole

3. The propulsion of blood into a non-compliant ventricle

4. The blood going in the wrong direction

The correct answer is: The beginning of ventricular systole

S1, also known as the first heart sound, signifies the closure of the mitral and tricuspid valves at the beginning of ventricular systole. This sound is a key indicator that the ventricles are contracting and that blood is being actively pumped out of the heart into the aorta and pulmonary arteries. The closure of the atrioventricular valves coincides with this phase, marking the transition from diastole to systole. Understanding the phases of the cardiac cycle is crucial for interpreting heart sounds. During diastole, the heart fills with blood, and the valves are open; however, as the heart prepares to pump the blood out during systole, the closure of these valves creates the distinct sound of S1 that can be heard with a stethoscope. This is an essential part of monitoring cardiac function, especially in progressive care environments where heart performance is critical. Other options might hint at various cardiac activities, but they do not accurately capture the significance of S1 in the context of the cardiac cycle. For instance, ventricular diastole refers to the filling phase of the heart, while the notion of non-compliant ventricles and blood flowing in the wrong direction addresses different pathophysiological concerns unrelated to S1.