Cardiac Sounds

Multiple Choice Questions (MCQs)

1. What causes the first heart sound (S1), commonly referred to as “Lub”?
   a) Closure of the semilunar valves
   b) Sudden tension of the chordae tendineae during ventricular filling
   c) Firm closure of the AV valves and ventricular muscle vibrations
   d) Stenosis of the pulmonary valve
   Answer: c) Firm closure of the AV valves and ventricular muscle vibrations
2. Which phase of the cardiac cycle is associated with the second heart sound (S2), or “Dub”?
   a) Rapid ventricular filling phase
   b) Isovolumetric contraction
   c) Protodiastole phase
   d) Atrial systole
   Answer: c) Protodiastole phase
3. The third heart sound (S3) is commonly heard in which animal?
   a) Dogs
   b) Cats
   c) Horses
   d) Cows
   Answer: c) Horses
4. What does the fourth heart sound (S4) signify in animals other than horses?
   a) Normal ventricular contraction
   b) AV bundle block or pathological conditions in dogs and cats
   c) Proper closure of semilunar valves
   d) Rapid filling of the ventricles
   Answer: b) AV bundle block or pathological conditions in dogs and cats
5. Which condition is commonly associated with cardiac murmurs in pigs?
   a) Valvular stenosis
   b) Erysipelas
   c) Congestive heart failure
   d) AV bundle block
   Answer: b) Erysipelas
6. What characterizes diastolic murmurs?
   a) Defective closure of the AV valves
   b) Insufficiency of the pulmonary or aortic valves
   c) Stenosis of the semilunar valves
   d) Proper closure of the mitral valve
   Answer: b) Insufficiency of the pulmonary or aortic valves
7. What is the primary cause of systolic murmurs?
   a) Stenosis of the AV valves
   b) Insufficiency of the aortic valves
   c) Defective closure of the mitral or tricuspid valves
   d) Congestive heart failure
   Answer: c) Defective closure of the mitral or tricuspid valves
8. Which heart sound is louder, low-pitched, and longer in duration?
   a) First heart sound (S1)
   b) Second heart sound (S2)
   c) Third heart sound (S3)
   d) Fourth heart sound (S4)
   Answer: a) First heart sound (S1)
9. What is the primary cause of cardiac murmurs?
   a) Proper functioning of valves
   b) Valvular insufficiency or stenosis
   c) Atrial contraction
   d) Ventricular relaxation
   Answer: b) Valvular insufficiency or stenosis
10. Which type of murmur is caused by stenosis of the AV valves?
    a) Systolic murmur
    b) Diastolic murmur
    c) Protodiastolic murmur
    d) Ejection murmur
    Answer: b) Diastolic murmur

Fill in the Blanks

1. The ________ heart sound (S1) occurs due to the firm closure of the AV valves.
   Answer: first
2. The ________ heart sound (S3) is commonly heard during early diastole in horses.
   Answer: third
3. Prolonged or adventitious heart sounds during silent intervals are referred to as ________.
   Answer: murmurs
4. Systolic murmurs result from improper closure of the ________ or ________ valves.
   Answer: mitral, tricuspid
5. ________ is a condition in pigs associated with valvular insufficiency and cardiac murmurs.
   Answer: Erysipelas

True or False

1. The second heart sound (S2) occurs during the closure of the AV valves.
   Answer: False
2. The third heart sound (S3) is pathological in animals other than horses.
   Answer: True
3. Cardiac murmurs are caused by proper closure of the heart valves.
   Answer: False
4. The first heart sound (S1) is longer and lower-pitched compared to the second heart sound (S2).
   Answer: True
5. Endocarditis can cause valvular insufficiency and is often associated with infections in pigs.
   Answer: True

Subjective Questions

1. Discuss the causes and clinical significance of cardiac murmurs.
   Answer:
   Cardiac murmurs are prolonged or abnormal heart sounds occurring during normally silent intervals of the cardiac cycle. They are caused by valvular insufficiency or stenosis of cardiac orifices.
   • Systolic murmurs: Result from defective closure of the mitral or tricuspid valves or stenosis of the pulmonary or aortic valves.
   • Diastolic murmurs: Caused by insufficiency of the pulmonary or aortic valves or stenosis of the AV valves.
     Murmurs indicate underlying cardiac abnormalities such as valvular disease, endocarditis, or congenital defects, and their detection aids in diagnosing and managing cardiac conditions.
2. Describe the characteristics and causes of the third and fourth heart sounds.
   Answer:
   • Third Heart Sound (S3): Occurs during early diastole at the end of rapid ventricular filling. It is caused by the sudden tension of chordae tendineae during ventricular filling. It is commonly heard in horses but may indicate congestive heart failure in other animals.
   • Fourth Heart Sound (S4): Occurs during atrial contraction due to tension on the AV valves. It is common in horses but may signify AV bundle block or pathological conditions in dogs and cats. These sounds provide insights into ventricular and atrial function, aiding in diagnosing specific cardiac disorders.