American Board of Internal Medicine (ABIM) Certification Practice Exam

In the diagnosis of moderate aortic regurgitation, what is the range for effective regurgitant orifice (ERO)?

1. Less than 0.10 cm2

2. Between 0.10 cm2 and 0.29 cm2

3. Between 0.30 cm2 and 0.40 cm2

4. Greater than 0.40 cm2

The correct answer is: Between 0.10 cm2 and 0.29 cm2

The effective regurgitant orifice (ERO) is a critical measurement used in assessing the severity of aortic regurgitation. It quantifies the size of the opening through which the blood regurgitates back into the left ventricle from the aorta during diastole. In the context of moderate aortic regurgitation, the ERO is specifically defined to range between 0.10 cm² and 0.29 cm². This range indicates that there is a significant amount of regurgitant flow that impacts the left ventricular volume and function without reaching the thresholds typical of severe regurgitation. ERO measurements less than 0.10 cm² suggest mild regurgitation, whereas ERO measurements greater than 0.29 cm² typically signify severe aortic regurgitation. Understanding the ERO helps clinicians classify the regurgitation and determine the appropriate management strategies for patients, including monitoring or surgical intervention if necessary.