23. Which of the following regurgitant fractions would be considered severe aortic valve regurgitation?

A. 10%

B. 20%

C. 30%

D. 40%

E. None of the above

The regurgitant fraction is the percentage of stroke volume that returns to the left ventricle from the aorta during diastole. For example, a regurgitant fraction of 33% would indicate that one-third of the total stroke volume returns to the left ventricle backwards across the aortic valve during diastole. A regurgitant fraction of < 20% indicates mild aortic regurgitation, 20-49% indicates moderate aortic regurgitation and > 50% severe aortic regurgitation.

  Jet Size Ratio Pressure Half-Time Regurgitant Fraction (%)
Mild <24 >500 <20
Moderate 25-64 500-250 20-49
Severe >65 <250 >50