In mitral stenosis, what is the primary hemodynamic abnormality?

In mitral stenosis, what is the primary hemodynamic abnormality?

• A. Increased left atrial pressure due to decreased left atrial emptying
• B. Increased left ventricular systolic pressure
• C. Decreased right atrial pressure
• D. Decreased left atrial pressure

Answer: (A)

The main idea is that mitral stenosis directly impairs filling of the left ventricle by narrowing the mitral opening during diastole. Because flow from the left atrium into the left ventricle is obstructed, the left atrium must generate higher pressure to push blood through the narrowed valve. This increased left atrial pressure is the primary hemodynamic abnormality and it backs up into the pulmonary veins, causing pulmonary congestion. Left ventricular systolic pressure is not the primary issue here; its systolic ejection is usually preserved, so systolic pressure in the ventricle remains normal or near normal despite the mitral obstruction. Right atrial pressure isn’t the primary abnormality either—though it can rise if pulmonary pressures increase from the backward flow, that occurs secondary to the left atrial and pulmonary venous pressures, not as the primary defect. Decreased left atrial pressure wouldn’t drive flow across a stenotic mitral valve, so it’s not correct.

The main idea is that mitral stenosis directly impairs filling of the left ventricle by narrowing the mitral opening during diastole. Because flow from the left atrium into the left ventricle is obstructed, the left atrium must generate higher pressure to push blood through the narrowed valve. This increased left atrial pressure is the primary hemodynamic abnormality and it backs up into the pulmonary veins, causing pulmonary congestion.

Left ventricular systolic pressure is not the primary issue here; its systolic ejection is usually preserved, so systolic pressure in the ventricle remains normal or near normal despite the mitral obstruction. Right atrial pressure isn’t the primary abnormality either—though it can rise if pulmonary pressures increase from the backward flow, that occurs secondary to the left atrial and pulmonary venous pressures, not as the primary defect. Decreased left atrial pressure wouldn’t drive flow across a stenotic mitral valve, so it’s not correct.