A nurse is discussing the blood flow pattern of the heart. The nurse should recognize which of the following as the accurate blood flow pattern of the heart?

A) S2 indicates the beginning of diastole:
While S2 does coincide with the end of systole and the beginning of diastole, this statement is not the most specific or accurate way to describe the S2 heart sound. S2 marks the closure of the semilunar valves (the aortic and pulmonic valves), which occurs at the end of systole, just before diastole begins. While it is true that the S2 sound occurs as the heart transitions from systole to diastole, the closure of the semilunar valves is the more specific cause of S2.

B) S2 coincides with the carotid artery pulse:
This statement is not accurate. S2 does not exactly coincide with the carotid pulse. The S2 sound is heard slightly after the pulse due to the time it takes for the mechanical contraction of the heart to produce the sound. The carotid pulse typically corresponds more closely with the closure of the atrioventricular (AV) valves and the beginning of systole (S1), not S2. The timing of S2 and the carotid pulse can be close, but they are not perfectly synchronized.

C) S2 is caused by the closure of the semilunar valves:
This is the correct explanation. S2 is the heart sound produced by the closure of the semilunar valves (the aortic and pulmonic valves). The closing of these valves marks the end of systole and the beginning of diastole. S2 is typically described as having two components: the A2 sound (closure of the aortic valve) and the P2 sound (closure of the pulmonic valve). In some cases, particularly during inspiration, A2 and P2 may be heard separately, producing a split S2 sound.

D) S2 is louder than an S1:
This statement is not accurate. In general, S1 is louder than S2 at the apex of the heart (the lower part of the chest). S2 is louder than S1 at the base of the heart (near the sternum), particularly over the aortic and pulmonic areas. The loudness of heart sounds varies based on the location of auscultation, but it is not universally true that S2 is always louder than S1. The intensity of each sound depends on various factors, including the position of the listener and the health of the heart valves.

A) Demonstrate that both arteries will be palpated simultaneously to compare amplitude: This is not recommended. Palpating both carotid arteries simultaneously can cause a decrease in blood flow to the brain, potentially leading to dizziness or syncope. It is important to palpate one carotid artery at a time to avoid reducing blood flow to the brain, especially in clients with cardiovascular disease or those at risk of stroke.

B) Instruct the client to take a deep breath and "hold" while the nurse briefly auscultates: This is the correct approach. Instructing the client to hold their breath helps minimize any interference from respiratory sounds while auscultating the carotid arteries for bruits. This technique ensures that breath sounds do not mask any abnormal vascular sounds, such as bruits, which could indicate a blockage or narrowing of the carotid arteries.

C) Discuss that a light will be directed at the neck to observe for pulsations of the artery: Observing pulsations with light is not an appropriate technique for assessing the carotid arteries. Pulsations may be visible in some cases, but palpation and auscultation are the more reliable methods for evaluating the carotid arteries for abnormalities such as bruits or reduced pulse amplitude.

D) Show the client the diaphragm of the stethoscope that will be placed on the neck: While it is appropriate to explain the process to the client, the action of showing the stethoscope is unnecessary at this stage. The focus should be on instructing the client to hold their breath for proper auscultation to listen for any abnormal vascular sounds.