问题
单项选择题
While auscultating heart sounds of a client with heart failure, the nurse hears an extra heart sound immediately after the second heart sound (S2). The nurse should document this as （）.
A．a first heart sound (S1).
B．a third heart sound (S3).
C．a fourth heart sound (S4).
D．a murmur.
答案
参考答案：B
解析：
An S3 is heard following an S2, which commonly occurs in clients experiencing heart failure and results from increased filling pressures. An S1 is a normal heart sound made by the closing of the mitral and tricuspid valves. An S4 is heard before an S1 and is caused by resistance to ventrieular filling. A murmur is heard when there's turbulent blood flow across the valves.