Mitral stenosis leads to increased pressures in the pulmonary circulation. Which statement is true?

Mitral stenosis leads to increased pressures in the pulmonary circulation. Which statement is true?

• A. Increased
• B. Decreased
• C. No change
• D. Variable

Answer: (A)

When the mitral valve is narrowed, flow from the left atrium to the left ventricle during diastole is impeded, so the left atrial pressure rises. That increased left atrial pressure backs up into the pulmonary veins and capillaries, elevating pulmonary venous and capillary pressures (and, over time, can raise pulmonary arterial pressures as well). So the pulmonary circulation pressures go up, which is why the statement is true. Decreased or no change would contradict the backward-filling mechanism, and while disease stage can influence the exact numbers, the typical direction is increased.

When the mitral valve is narrowed, flow from the left atrium to the left ventricle during diastole is impeded, so the left atrial pressure rises. That increased left atrial pressure backs up into the pulmonary veins and capillaries, elevating pulmonary venous and capillary pressures (and, over time, can raise pulmonary arterial pressures as well). So the pulmonary circulation pressures go up, which is why the statement is true. Decreased or no change would contradict the backward-filling mechanism, and while disease stage can influence the exact numbers, the typical direction is increased.