AV Valve Regurgitation Effects Steps:

• Incomplete AV valve closure causes blood to regurgitate into the atrium during ventricular systole.
• Regurgitant volume increases atrial blood volume, elevating atrial pressure.
• Net forward blood flow from the ventricle decreases due to backward leakage.
• Reduced left ventricular output lowers overall cardiac output, decreasing pulmonary artery inflow.

Why D is correct:

• Mitral regurgitation definition: backward flow raises left atrial pressure (v wave), while reduced stroke volume decreases pulmonary artery blood flow via lower systemic return and cardiac output.

Why the others are wrong:

• A: Oxygenation depends on pulmonary capillary exchange, not immediate volume reduction.
• B: Diastolic LV pressure relates to preload, which may rise from volume overload, not fall.
• C: Systolic LA pressure rises from regurgitant volume, not lowers; forward flow reduction affects aorta, not pulmonary artery as stated.

Final answer: D