Which of the following is/are not true?

C. Tricuspid regurgitation is most commonly caused by abnormalities of the leaflets themselves.

D. Mitral valve replacement requires resection of the mitral valve leaflets and chordae. 

DISCUSSION: Relative to medical therapy alone, surgical therapy has been shown to improve survival in patients with severe, symptomatic mitral valve disease. In mitral regurgitation, left ventricular dilatation is an indication for surgical intervention regardless of failure symptoms. The most common cause of tricuspid regurgitation is tricuspid annular dilatation without abnormalities of the leaflets themselves. Mitral valve replacement with preservation of both leaflets or at least the posterior leaflet is well described and is probably advisable for most patients to preserve left ventricular function and reduce the probability of ventricular-annular separation.