Significant aortic regurgitation can cause an underestimation of mitral stenosis severity due to increased left ventricular diastolic pressures. Which option best describes the mechanism?

Significant aortic regurgitation can cause an underestimation of mitral stenosis severity due to increased left ventricular diastolic pressures. Which option best describes the mechanism?

• A. Increased LV diastolic pressures
• B. Decreased LV diastolic pressures
• C. Reduced LA pressure
• D. Reduced LV systolic pressure

Answer: (A)

Elevated LV diastolic pressure changes the pressure difference across the mitral valve during diastole. In mitral stenosis, Doppler estimates severity from the transmitral gradient, which depends on the pressure the left atrium provides minus the pressure in the LV during diastole. When significant aortic regurgitation raises LV diastolic pressure, this LV-side pressure pushes up, narrowing the gradient for a given amount of mitral flow. That makes the observed gradient appear smaller than the actual stenosis would suggest, leading to underestimation of severity. So the best description is that LV diastolic pressures are increased. The other options don’t produce the same effect: lowering LV diastolic pressure would enlarge the gradient, and changes in LA or LV systolic pressure don’t explain the underestimation mechanism in this context.

Elevated LV diastolic pressure changes the pressure difference across the mitral valve during diastole. In mitral stenosis, Doppler estimates severity from the transmitral gradient, which depends on the pressure the left atrium provides minus the pressure in the LV during diastole. When significant aortic regurgitation raises LV diastolic pressure, this LV-side pressure pushes up, narrowing the gradient for a given amount of mitral flow. That makes the observed gradient appear smaller than the actual stenosis would suggest, leading to underestimation of severity.

So the best description is that LV diastolic pressures are increased. The other options don’t produce the same effect: lowering LV diastolic pressure would enlarge the gradient, and changes in LA or LV systolic pressure don’t explain the underestimation mechanism in this context.