Summary: This two-part article examines the histologic and morphologic basis for stenotic and purely regurgitant mitral valves. In Part I, conditions producing mitral valve stenosis are reviewed. In over 99% of stenotic mitral valves, the etiology is rheumatic disease. Other rare causes of mitral stenosis include congenitally malformed valves, active infective endocarditis, massive annular calcium, and metabolic or enzymatic abnormalities. In Part II, conditions producing pure mitral regurgitation will be discussed. In contrast to the few causes of mitral stenosis, the causes of pure (no element of stenosis) mitral reguqytation are multiple. Some of the conditions producing pure regurgitation include floppy mitral valves, infective endocarditis, papillary muscle dysfunction, rheumatic disease, and ruptured chordae tendineae.Key words: mitral stenosis, rheumatic heart disease, mitral regurgitation, mitral valve General Concepts of Function and PathologyMitral valve dysfunction can result from structural alterations (congenital or acquired) of the valve or from abnormal function of a structurally normal valve.' From an etiologic standpoint, it is useful to divide mitral valve dysfunction into either stenotic orpurely regurgitant types. Most stenotic mitral valves are associated with clinical evidence (auscultation, Doppler echocardiography, angiography) of some element of regurgitation, but by definition, pure mitral regurgitation has no element of stenosis.' Although clinically and therapeutically useful, knowledge of whether a mitral valve is both stenotic and regurgitant, or which hemodynamic lesion is dominant, is less helpful in estab lishing etiology of the mitral valve dysfunction. Stenotic mitral valves are always anatomically abnormal (fibrous thlckening, calcific deposits, or both) and the causes for stenosis are limited to a few conditions. In contrast, purely regurgitant mitral valves may or may not have some anatomic abnormality, and the causes for pure regurgitation are multiple. With the exception of congenital causes, stenotic mitral valves usually take years to develop, but purely regurgitant mitral valves may develop acutely or chronically. ' 7 In a recent survey of operatively excised cardiac valves3 the mitral valve was the second most frequently excised native cardiac valve. Of 2,980 excised valves (2,566 patients), 1,398 (47%) were mitral. Of the 1,398 excised mitral valves, 1,154 (83%) were classified as stenotic (with or without associated regurgitation) and 244 (17%) were purely regurgitant (Fig. 1). Three additional studiesM have evaluated over 500 operatively excised mitral valves. The functional classification was stenotic in 45%4 to 63%6 and purely regurgitant in 37%6 to 55%?A decline over a 2 1 -year period in the relative frequency of operatively excised stenotic mitral valves versus purely regurgitant mitral valves has recently been reported by Olson and colleagues6 The frequency of excised stenotic mitral valves decreased from 79% in 1965 to 43% in 1985, while the frequency of ex...

A total of 337 patients undergoing coronary artery bypass grafting or cardiac valve replacement were randomly assigned to receive cefazolin (1 g every 8 h [q8h]), cefamandole (2 g q6h), or cefuroxime (1.5 g ql2h) as an intravenous antibiotic prophylaxis. All drugs were administered within 60 min before the initial incision and were continued for 48 h postoperatively. No adverse effects related to the study drugs were observed. The percentage of patients with postoperative infection was 9% for the cefazolin group, 6% for the cefamandole group, and 5% for the cefuroxime group or 6.5% overall. There were more infection sites in patients treated with cefazolin than in those treated with cefuroxime (P = 0.05) or cefamandole (P = 0.06). Fewer wound infections ocwcurred with cefuroxime (P < 0.01) and cefamandole (P = 0.06) than with cefazolin. Analyses of the prophylactic regimens used in this study showed cefazolin and cefuroxime to be less costly than cefamandole.

Summary:This two-part article examines the histologic and morphologic basis for stenotic and purely regurgitant aortic valves. Part I discussed stenotic aortic valves and Part II discusses causes of purely regurgitant aortic valves. In over 95% of stenotic aortic valves, the etiology is one of three types: congenital (primarily bicuspid), degenerative, and rheumatic. Other rare causes included active infective endocarditis, homozygous type 11 hyperlipoproteinemia, and systemic lupus erythematosis. The causes of pure aortic regurgitation are multiple but can be separated into diseases affecting the valve (normal aorta) (infective endocarditis, congenital bicuspid, rheumatic, floppy), diseases affecting the walls of aorta (normal valve) (syphilis, Marfan's, dissection), disease affecting both aorta and valve (abnormal aorta, abnormal valve) (ankylosing spondylitis), and disease affecting neither aorta nor valve (normal aorta, normal valve) (ventricular septal defect, systemic hypertension). Diseases affecting the aortic valve alone are the most common subgroup of conditions producing purely regurgitant aortic valves.

Summary: This three-part article examines the histologic and morphologic basis for stenotic and purely regurgitant tricuspid valves.In Part 1, conditions producing tricuspid valve stenosis are reviewed. In over 90% of stenotic tricuspid valves, the etiology is rheumatic disease. In isolated tricuspid stenosis, the etiology is either carcinoid or congenital. Rare causes of tricuspid stenosis include active infective endocarditis, metabolic or enzymatic abnormalities (Fabry's, Whipple's disease), and giant blood cysts.

This two-part article examines the histologic and morphologic basis for stenotic and purely regurgitant mitral valves. In Part I, conditions producing mitral valve stenosis were reviewed. In over 99% of stenotic mitral valves, the etiology is rheumatic disease. Other rare causes of mitral stenosis include congenitally malformed valves, active infective endocarditis, massive annular calcium, and metabolic or enzymatic abnormalities. In Part II, conditions producing pure mitral regurgitation are discussed. In contrast to the few causes of mitral stenosis, the causes of pure (no element of stenosis) mitral regurgitation are multiple. Some of the conditions producing pure regurgitation include floppy mitral valves, infective endocarditis, papillary muscle dysfunction, rheumatic disease, and ruptured chordae tendineae.