33. What are the causes of diastolic mitral regurgitation?

Diastolic mitral regurgitation can occur in the setting of complete heart block when the atrium contracts early after ventricular contraction resulting in a prolonged left ventricular filling period increasing LV pressure toward end-diastole despite a lower left atrial pressure. The regurgitant volume is thought to be small and clinically insignificant, nevertheless it can be detected on echocardiography. This phenomenon simply stresses the importance of normal AV synchrony to maintain normal left ventricular filling and overall cardiac output.

Aortic regurgitation and severe cardiomyopathies have also been shown to cause some degree of diastolic mitral regurgitation.