American Board of Internal Medicine (ABIM) Certification Practice Exam

What is the significance of a mean gradient of 40 mm Hg in heart valve disease?

1. It indicates mild stenosis

2. It indicates severe stenosis

3. It indicates normal function

4. It indicates moderate stenosis

The correct answer is: It indicates severe stenosis

A mean gradient of 40 mm Hg is clinically significant as it typically indicates severe stenosis, particularly in the context of valvular heart disease, such as aortic stenosis. In this condition, the mean gradient reflects the pressure difference across the affected valve during systole. A mean gradient of 40 mm Hg is generally used as a threshold, with values above this indicating significant obstruction to blood flow. In aortic stenosis, for example, normal mean gradient values are much lower; mild stenosis typically presents with gradients less than 20 mm Hg. Therefore, as the gradient increases, the severity of the stenosis increases, with gradients of 40 mm Hg or greater aligning with severe constriction. Therefore, a mean gradient of this level suggests that the heart is working significantly harder to pump blood through the narrowed valve, which can lead to symptoms such as exertional dyspnea, angina, or syncope. Recognizing these values helps in determining the appropriate clinical management, such as timing for surgical intervention or valve replacement, making the understanding of these gradients essential for effective patient care in heart valve disease.