What would mitral regurgitation do to the LV pressure-volume loop?

• A. The loop narrows and shifts left.
• B. End-diastolic volume decreases.
• C. Regurgitation increases forward stroke volume.
• D. Preload increases due to regurgitant volume; EDV increases; forward SV may decrease; PV loop widens to the right.

Answer: (D)

Mitral regurgitation creates a volume overload for the left ventricle. During systole, some blood is ejected backward into the left atrium instead of all into the aorta. That regurgitated blood returns to the ventricle with the next heartbeat, increasing the preload. In practical terms, the end-diastolic volume rises, so the LV starts each beat with a larger preload and a higher EDV. Because part of the stroke volume is lost to the low-pressure LA, the forward (aortic) stroke volume can decrease. On the pressure-volume loop, this shows up as a shift to the right (higher EDV) and a wider loop (greater volume change), reflecting both the increased preload and the altered distribution of the stroke volume.