Mitral valve regurgitation is most accurately described as:

• A. Bacterial infection of the mitral valve.
• B. Calcification of valve leaflets.
• C. Myxomatous changes in the mitral valve prolapse.
• D. Trauma causing valve rupture.

Answer: (C)

Mitral regurgitation happens when the mitral valve doesn’t close properly during systole, so blood leaks back from the left ventricle into the left atrium. The most common degenerative cause is myxomatous degeneration of the valve tissue, which makes the leaflets thick and floppy and leads to mitral valve prolapse. When the leaflets prolapse into the left atrium, they fail to coapt tightly, allowing a regurgitant jet of blood during systole. Over time this backflow can cause volume overload of the left heart and contribute to symptoms or heart failure if severe. Other options describe different valve problems—infection can damage valves (endocarditis), calcification stiffens leaflets and is more associated with stenosis, and trauma can cause acute rupture—but for explaining chronic mitral regurgitation, myxomatous changes with prolapse is the best fit.