title: Mechanism of reducing platelet activity by percutaneous transluminal mitral valvuloplasty in patients with rheumatic mitral stenosis.
abstract: BACKGROUND
  Previous studies have demonstrated that platelet activity significantly decreased after optimal percutaneous transluminal mitral valvuloplasty (PTMV) in patients with rheumatic mitral stenosis (MS). However, the mechanism of reducing platelet activity by valvuloplasty remains unclear.
  
  
  RESULTS
  We studied 19 patients with symptomatic MS who were undergoing PTMV. The fractions of unstimulated platelets expressing P-selectin in the venous blood obtained before, and at the 1-week and 4-week follow-ups after PTMV were determined by flow cytometry. The mitral valve areas, measured before and at the 1-week follow-up after PTMV, were calculated by means of the Doppler pressure half-time method. The mean (+/- SD) area of the mitral valve increased significantly after PTMV (1.05 +/- 0.17 vs 1.44 +/- 0.27 cm2, respectively; p < 0.0001). The mean left atrial area was reduced in size significantly after PTMV (36.6 +/- 11.4 vs 33.9 +/- 13.4 cm2, respectively; p < 0.05). The mean left atrial pressure (23.3 +/- 5.1 vs 18.0 +/- 5.8 mm Hg, respectively; p < 0.0001) and the mean pulmonary arterial pressure (31.4 +/- 7.8 vs 26.1 +/- 7.7 mm Hg, respectively; p < 0.0001) fell significantly after PTMV. The fraction of platelets expressing P-selectin in the venous blood fell significantly after PTMV (before PTMV, 4.7 +/- 2.4%; 1 week after PTMV, 2.2 +/- 2.1%; 4 weeks after PTMV, 2.0 +/- 1.7%; p < 0.0001). Correlation analysis demonstrated that there was a significantly direct relationship between the magnitude of increase in mitral valve area and the magnitude of decrease in the fraction of platelets expressing P-selectin in the venous blood 4 weeks after PTMV (p = 0.0013; r = 0.682). However, there was no significant correlation between the magnitude of decrease in the fraction of platelets expressing P-selectin in the venous blood and the magnitude of decrease in the left atrial area, the decrease in left atrial pressure, or the decrease in the pulmonary artery pressure after PTMV.
  
  
  CONCLUSIONS
  In patients with moderate-to-severe MS, increased platelet activation fell significantly after PTMV. It was the increase in mitral valve area by PTMV, instead of hemodynamic and echocardiographic factors, that accounted for the decrease in the fraction of venous platelets expressing P-selectin after PTMV.
authors.affiliation: Department of Internal Medicine, Division of Cardiology, Chang Gung Memorial Hospital, Kaohsiung, Taiwan, ROC. chenmien@ms76.hinet.net
authors.forename: Mien-Cheng
authors.initials: MC
authors.lastname: Chen
authors.forename: Chiung-Jen
authors.initials: CJ
authors.lastname: Wu
authors.forename: Hsueh-Wen
authors.initials: HW
authors.lastname: Chang
authors.forename: Hon-Kan
authors.initials: HK
authors.lastname: Yip
authors.forename: Yen-Hsun
authors.initials: YH
authors.lastname: Chen
authors.forename: Cheng-I
authors.initials: CI
authors.lastname: Cheng
authors.forename: Han-Tan
authors.initials: HT
authors.lastname: Chai
mesh_terms: D000328:Adult; D000368:Aged; D001792:Blood Platelets / Q000378:metabolism*; D002404:Catheterization; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008946:Mitral Valve Stenosis / Q000097:blood / Q000209:etiology / Q000473:pathology / Q000628:therapy*; D019007:P-Selectin / Q000096:biosynthesis* / Q000097:blood; D015539:Platelet Activation; D012214:Rheumatic Heart Disease / Q000150:complications
chemical_list: D019007:P-Selectin