S1 VARIATIONS

Question 1

• S1 is softer than S2 at base, and usually louder at apex

Answer 1

Normal

Question 2

• Tachycardia
• Rhythms with short PR intervals
• High cardiac output states (exercise, hyperthyroidism, etc.)
• Mitral stenosis (valve still open at beginning of LV systole and closes quickly)

Answer 2

Accentuated S1

Question 3

• 1st degree heart block (atria/ ventricles beating independently)
• Left bundle branch block
• Myocardial infarction due to weak ventricle contraction
• Acute aortic regurgitation (mitral valve closes before ventricle contraction)

Answer 3

Diminished S1

Question 4

• Complete heart block (atria and ventricle beating independently)
• Any totally irregular (atrial fibrillation; mitral valve in varying positions before ventricle contraction)

Answer 4

Varying S1

Question 5

• Delayed closure of tricuspid valve
• Prominent when RV contraction is delayed (right bundle branch block and left premature
  contractions)

Answer 5

Split S1