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.
In mitral valve regurgitation, the mitral valve doesn't close tightly. With each heartbeat, some blood from the left ventricle flows backward into the left atrium instead of moving forward into the aorta. This essentially means that the heart pulls blood backward.ossible causes of mitral valve regurgitation include: 1  Mitral valve prolapse. 2  In this condition, the leaflets and tendon-like cords supporting the mitral valve weaken and stretch so that with each contraction of the left ventricle, the valve leaflets bulge (prolapse) into the left atrium.