What will be seen on M-mode echocardiography with moderate/severe chronic mitral regurgitation?

What will be seen on M-mode echocardiography with moderate/severe chronic mitral regurgitation?

• A. Premature closure of the aortic valve
• B. Prolapsed mitral valve
• C. Normal M-mode tracing
• D. Increased left ventricular posterior wall thickness

Answer: (A)

In moderate to severe chronic mitral regurgitation, the left ventricle is volume overloaded and ejects part of its stroke volume back into the left atrium. That regurgitant flow unloads the LV during systole, lowering the peak LV systolic pressure and allowing the LV pressure to drop sooner. Because the aortic valve closes when LV pressure falls below the aortic pressure, this earlier drop causes the aortic valve to close sooner than normal. On M-mode tracing, this appears as premature closure of the aortic valve. Prolapsed mitral valve is a structural issue that isn’t the typical, consistent M-mode finding in this scenario. A normal M-mode tracing wouldn’t reflect a significant MR, and increased left ventricular posterior wall thickness points to hypertrophy from other conditions rather than the hallmark MR-related LV dilation and the timing change of valve closure.

In moderate to severe chronic mitral regurgitation, the left ventricle is volume overloaded and ejects part of its stroke volume back into the left atrium. That regurgitant flow unloads the LV during systole, lowering the peak LV systolic pressure and allowing the LV pressure to drop sooner. Because the aortic valve closes when LV pressure falls below the aortic pressure, this earlier drop causes the aortic valve to close sooner than normal. On M-mode tracing, this appears as premature closure of the aortic valve.

Prolapsed mitral valve is a structural issue that isn’t the typical, consistent M-mode finding in this scenario. A normal M-mode tracing wouldn’t reflect a significant MR, and increased left ventricular posterior wall thickness points to hypertrophy from other conditions rather than the hallmark MR-related LV dilation and the timing change of valve closure.