Mitral Incompetence - The back flow of blood from the left ventricle into the left atrium through a defective mitral bicuspid valve, which cannot completely close. The most common cause for mitral regurgitation is rheumatic fever.
 
Mitral Stenosis - The narrowing and ineffective opening of the mitral valve.
 
Mitral Valve - The heart valve that divides the left atrium and left ventricle. During left atrial contraction, the mitral valve opens, allowing blood to flow into the left ventricle. The mitral valve is the only heart valve that has only 2 valve cusps (all others have 3).
 
Mitral Valve Prolapse - A systolic click-murmur syndrome, floppy-valve syndrome. A common, but highly variable clinical syndrome that has been described in up to 7% of all females in the 14 to 30 age group. Usually there are no symptoms. Occasionally, the prolapse may cause chest pain, palpitations, labored breathing or fatigue. Treatment often includes the avoidance of stimulants (caffeine, nicotine, decongestants) and the use of a beta-blocker medication in select cases.
 
Murmur - A clicking or rasping sound heard between the heart beats.
 
Myocardial Infarction - Heart attack. The infarction of an area of the heart muscle, usually as a result of a blocked coronary artery.
 
Myocardium - The muscles which make up the walls of the heart.