Question

The fourth heart sound

Select one:
a. indicates increased pressure in the atria.
b. represents increased left ventricular stretching.
c. occurs immediately before the S2 sound.
d. is normal in 25% of the population.

Answer 1

The fourth heart sound, S4, is caused by atrial contraction pushing blood into a stiff or hypertrophic ventricle, indicating potential left ventricular failure. It occurs immediately before the first heart sound (S1).

Step-by-step explanation:

The fourth heart sound, S4, is an indication of atrial contraction and occurs just before the first heart sound, S1. It results from the contraction of the atria pushing blood into a stiff or hypertrophic ventricle, which is indicative of failure of the left ventricle.


In contrast, S2 represents the closing of semilunar valves and occurs after S1. S4 is not a normal finding and is not heard in healthy individuals.


Consequently, the fourth heart sound:

• indicates increased pressure in the atria.
  
  
• represents increased left ventricular stretching.
  
  
• occurs immediately before the S1 sound.
  
  
• is normal in 25% of the population.
  
  

Therefore, the correct answer is that the fourth heart sound occurs immediately before the S1 sound.