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Objectives : To study the pathology, determine the etiology and prevalence of mitral valve disease from surgically removed mitral valve specimens.
Materials and Methods : All the native surgically excised mitral valves (MV) received during June 1997 to March 1999 (22 months) were studied macroscopically and microscopically. By preoperative echocardiographic and macroscopic studies, they were classified into functional disorders of predominant mitral stenosis (MS), mitral stenosis with regurgitation (MS-MR) and predominant mitral regurgitation (MR). The patients' medical records were reviewed and the clinical information was extracted. The etiology was determined according to the macroscopic, microscopic and clinical findings.
Results : Among 154 MV (120 isolated MV and 34 with concomitant aortic valves from patients aged 7-79 years, mean age 43.98 years) there were 68 MS (44.16%), 30 MS-MR (19.48%) and 56 MR (36.36%) cases. All MS cases (age range 10 - 65 years, mean age 45.37 years, male : female = 1:1.51), all MS-MR cases (age range 20 - 66 years, mean age 40.03 years; male : female = 1:1.31) and 20 of 56 MR cases (35.71% of MR cases, 12.98% of total cases, age range 8 - 63 years, mean age 31.21 years, male : female = 1.22 : 1) were attributable to post-inflammatory disease. Prominent calcification occurred in 76.47% of MS, 70% of MS - MR and 25% of post-inflammatory disease MR cases. Moderate to marked neovascularization was found in 34.32% of MS, 56.66% of MS-MR and 65% of MR cases. Aschoff bodies were found in 1 MS and 4 MR cases. Eight of 39 MS (20.51%), 4 of 16 MS-MR (25%) and 6 of 13 (46.15%) post-inflammatory disease MR cases had past history of rheumatic fever. Other causes of pure MR included floppy valves (18 cases, 32.14% of MR cases, age range 40 - 79 years, mean age 61.72 years, male : female = 3.5 : 1;15 cases with chordal rupture), infective endocarditis (IE) [7 cases including one with post-inflammatory disease MS and one post-IE (age range 20 - 50 years, mean age 34.12 years, male : female = 6 : 1) with gram positive cocci in all IE], papillary muscle necrosis (1 case), ruptured necrotic papillary muscle (1 case), miscellaneous and indeterminate cause (4 cases). In comparison with post-inflammatory MR, posterior leaflet in floppy MR had longer basal-free edge length (mean basal-free edge length of floppy valve = 16.65 mm. p <.0001)and more frequent chordal rupture. Among MS and MS-MR post-inflammatory valves, 90.81% were completely excised whereas partial specimens were received in 40% of post-inflammatory MR, 61% of floppy valves and 50% of miscellaneous cases.
Conclusion : Post-inflammatory disease (presumably rheumatic fever associated) of MV is still a main valvular heart disease in Thai patients undergoing valvular operation as it accounted for 75.97% of all MV specimens. In pure MR, the three most common causes were post-inflammatory disease, floppy valve and infective endocarditis. Macroscopic and microscopic examinations together with clinical information, echocardiographic findings and operative details are important in the evaluation of the etiology of valvular disease especially in partial specimens.
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