American Board of Internal Medicine (ABIM) Certification Practice Exam

Which condition is characterized by a Vmax of ≥4 m/s or a mean gradient of ≥40 mm Hg?

1. Mild aortic stenosis

2. Moderate aortic stenosis

3. Severe aortic stenosis

4. Very severe aortic stenosis

The correct answer is: Severe aortic stenosis

The condition characterized by a Vmax (maximum velocity of blood flow across the valve) of ≥4 m/s or a mean gradient of ≥40 mm Hg is indeed severe aortic stenosis. In severe aortic stenosis, the significant obstruction to blood flow through the aortic valve results in high velocity across the valve. When the maximum velocity reaches 4 m/s or the mean gradient across the valve is at least 40 mm Hg, it indicates a substantial pressure difference that the heart must overcome to eject blood through the narrowed valve. This level of obstruction is associated with more pronounced symptoms and hemodynamic changes, which can include decreased cardiac output and increased left ventricular workload. In contrast, mild and moderate aortic stenosis are characterized by lower velocities and mean gradients, indicating less severity and often a lower risk of significant symptoms or complications. Very severe aortic stenosis would generally refer to even higher values than those described for severe aortic stenosis, often involving more critical hemodynamic compromise. Thus, the identification of severe aortic stenosis based on these hemodynamic parameters is essential for appropriate management and intervention.