Percutaneous balloon mitral valvuloplasty: a review.

Several diseases have been acknowledged as pathological causes for mitral valve stenosis (MS), of which rheumatic heart disease is the most prevalent. Rheumatic heart disease is a chronic manifestation of rheumatic carditis, which occurs in 60% to 90% of cases of rheumatic fever. Rheumatic fever is a late sequela to Group A -hemolytic streptococcal infection of the throat. The initial rheumatic fever results only in an edematous inflammatory process, leading to the fibrinoid necrosis of the connective tissue and cellular reactions. The initial valvulitis results in verruciform deposition of fibrin along the closing portion of the leaflets. Although all of the cardiac valves may be involved by this rheumatic process, the mitral valve is involved most prominently. The endocardial lesion most often leaves permanent sequela resulting in valvular regurgitation, stenosis, or both. Stenosis of this valve occurs from leaflet thickening, commissural fusion, and chordal shortening/fusion due to the above described pathological process.