Direct Detection of Activated Platelets in the Patients with Prosthetic Heart Valve by Flow Cytometry and its Pathophysiological Significance

Thromboembolism is frequently observed in patients with prosthetic heart valve and is believed to be a major cause of post-operative morbidity and mortality. The aim of this study is to elucidate the role of activated platelets in the patients with prosthetic heart valve. Forty patients (23 female and 17 male) were operated on between 1967 and 1994 for prosthetic heart valve replacement in our university. Mean age was 55 years (range 2～68). All patients received anti-coagulant therapy. In 40 patients with prosthetic heart valve and 20 normal subjects, activated platelets were detected by flow-cytometric measurement of the proteins CD62P and CD63, which are expressed on the platelet surface membrane during platelet activation. Among healthy volunteers, a small percentage of platelets were activated (CD62P: 3.14±0.82%, CD63: 3.53±1.29%). In contrast, the patients group showed increased percentage of activated platelets. (CD62P: 4.08±2.25%, p=N.S., CD63: 4.82±2.70%, p<0.05). In order to elucidate the pathophysiological role of the activated platelets in the patients, the 40 patients were divided into two groups according to the percentage of the activated platelets; activated platelets group (CD62P≧4.77% or CD63≧6.26%) and non-activated platelets group (CD62P<4.77% and CD63<6.26%). In the two groups, I analyzed the difference of four clinical factors, 1) history of prior cerebral infarction, 2) adequacy of anti-coagulant therapy (thrombotest