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.
1 Heart attack. 2  A heart attack can damage the area of the heart muscle that supports the mitral valve, affecting the function of the valve. 3  If the damage is extensive enough, a heart attack can cause sudden and severe mitral valve regurgitation. 4  Abnormality of the heart muscle (cardiomyopathy).