Erythema multiforme (EM) is a skin reaction that comes from an infection or another trigger. EM is a type of allergic reaction. In most cases, it occurs in response to an infection. In rare cases, it is caused by certain medicines or body-wide (systemic) illness. Infections that may lead to EM include:
The most common causes of sudden (acute) aortic valve regurgitation include: 1  Endocarditis, which is an infection in the heart. 2  Aortic dissection, which means that the inner layer of the aorta separates from the middle layer. 3  Problems with a replacement (artificial) aortic valve.  Trauma to the heart valve or aorta.
Mitral valve prolapse and regurgitation. Mitral valve prolapse and regurgitation The mitral valve separates the two chambers (atrium and ventricle) of the left side of the heart. In mitral valve prolapse, the leaflets of the mitral valve bulge (prolapse) into the left atrium like a parachute during the heart's contraction. Sometimes mitral valve prolapse causes blood to leak back into the atrium from the ventricle, which is called mitral valve regurgitation.