Evaluation of surgically excised mitral valves: revised recommendations based on changing operative procedures in the 1990s.

In 1990, 95 mitral valves from 54 women and 41 men (mean age, 61 years; age range, 8 to 85 years) were replaced (76%) or repaired (24%) at the Mayo Clinic. Functionally, 58% of the valves were purely regurgitant (MR), 25% were stenotic and regurgitant (MS-MR), and 17% were purely stenotic (MS). Postinflammatory (presumably rheumatic) disease accounted for 100% of MS cases, 92% of MS-MR cases, and 16% of MR cases. Other causes of pure MR included floppy valves (49%), ischemic heart disease (13%), infective endocarditis (9%), miscellaneous (9%), and indeterminate (4%). Thus, postinflammatory disease represented the major cause of both mitral stenosis (MS and MS-MR) and overall mitral valve disease in our surgical population. In contrast, floppy valves were the most commonly observed cause of pure MR. Among postinflammatory valves, 55% were completely excised and 45% had only the anterior leaflet removed; all were replaced. In contrast, floppy valves were incompletely excised in 96%; 67% were repaired and only 33% were replaced. Because mitral valves frequently are incompletely excised, rendering an accurate etiologic diagnosis requires not only a morphologic assessment of resected tissues but also a knowledge of the clinical history, operative details, and functional state of the valve.