Coagulation, fibrinolysis and platelet P-selectin expression in peripheral vascular disease.

OBJECTIVES: to examine coagulation, fibrinolysis, and platelet activity in patients with peripheral vascular disease (PVD). DESIGN: fifty consecutive PVD patients and 50 healthy volunteers. (Prospective comparative study.) MATERIALS AND METHODS: P-selectin expression in non-fixed, whole blood was measured flow cytometrically on non-stimulated and ADP- and TRAP-6-stimulated samples. Plasma fibrinogen, von Willebrand factor (vWF), tissue plasminogen activator (tPA), and plasminogen activator inhibitor-1 were determined using standard techniques. Disease severity was stratified on the basis of the ankle-brachial pressure index (ABPI) and the angiographic data were assessed using the Bollinger score. RESULTS: coagulation and fibrinolysis parameters as well as the P-selectin expression on both stimulated and non-stimulated platelets were significantly increased in patients vs controls (all p<0.01). The respective sensitivity and specificity were as follows: P-selectin expression (81%, 94%), vWF (72%, 86%), fibrinogen (64%, 98%), PAI-1 (44%, 90%), tPA (15%, 100%). P-selectin expression on TRAP-6-stimulated MP correlated with disease severity (r=0.40, p<0.01). CONCLUSIONS: these findings support the concept of ongoing thrombogenesis in the subclinical progression of PVD and demonstrate the high diagnostic sensitivity of flow cytometric analysis of platelet activation.

P-Selectin expression, platelet aggregates, and platelet-derived microparticle formation are increased in peripheral arterial disease.

Platelet volume has been reported to be increased in vascular disease. Therefore, we studied the relationship of mean platelet volume and platelet count as well as flow cytometrically measured platelet size and platelet function in 50 patients with peripheral arterial disease and 50 healthy volunteers. Platelet activation was measured by P-selectin expression analysis on resting and on stimulated platelets, and the determination of platelet aggregates and platelet-derived microparticles using flow cytometry. P-Selectin expression on platelets was significantly elevated in patients suffering from peripheral arterial disease (all P<0.0001). Platelet aggregates (P<0.0001) and platelet-derived microparticles (P<0.0001) were significantly higher in the patient group compared with controls, whereas mean platelet volume and platelet count showed no significant differences. Platelet count was inversely related to mean platelet volume in patients and controls (r = -0.43, P<0.001). The present study supports the hypothesis of platelet hyperreactivity and circulating activated platelets in peripheral arterial disease. Mean platelet volume, and platelet count cannot be used as predictive markers for platelet activation in peripheral arterial disease patients.

Changes in signal transduction in the platelets of patients with peripheral occlusive arterial disease.

BACKGROUND: The finding that platelets of patients with peripheral occlusive arterial disease (POAD) circulate in an activated state prompted us to study platelet signal transduction. We hypothesised that platelet hyperreactivity is caused by changes in intracellular signalling. EXPERIMENTAL DESIGN: a single blood sample was taken from the antecubital vein of each participant prior to the start of intravenous treatment with prostaglandins. SETTING: patients were recruited from our inpatient Department of Cardiology and Angiology at the University Hospital. PARTICIPANTS: 15 hospitalised patients with symptomatic POAD were randomly selected. Patients receiving antiplatelet drugs and those with diabetes were excluded. The control group consisted of 15 healthy volunteers from the medical staff. INTERVENTIONS: blood tests were performed on the day of admission before any therapeutic intervention. MEASURES: the platelet activation marker P-selectin was quantified on peripheral blood platelets before and after in vitro stimulation with platelet agonists (adenosine diphosphate, thrombin receptor activator peptide-6). The signal transduction cascade was also selectively blocked by preincubation with either: 1) forskolin, 2) phospholipase C inhibitor U-73122, or 3) bisindolylmaleimide. RESULTS: A stronger inhibitory effect on ADP-stimulated platelets was seen in patients with U-73122, as indicated by a decrease in mean fluorescence intensity of 51% versus 34% in controls (p<0.0005). CONCLUSIONS: Our findings support the assumption that changes in platelet signal transduction in POAD lead to platelet hyper-reactivity.

Haemostatic derangement in advanced peripheral occlusive arterial disease.

BACKGROUND: Dysbalance of the coagulation and fibrinolysis system was suspected to be a further risk factor for the progression of peripheral occlusive arterial disease (POAD). Reports on disturbed platelet function in advanced disease, however, were contradictory. Therefore, we studied haemostasis parameters and platelet function in symptomatic patients with peripheral arterial disease. METHODS: 60 peripheral arterial disease patients hospitalised for invasive diagnostic procedures were included into this comparative study. Patients were clinically stratified according to the criteria for chronic limb ischemia (grade I: n=36; grade II: n=11; grade III: n=13). Plasma fibrinogen, antithrombin III, von Willebrand factor, tissue plasminogen activator (tPA), plasminogen activator inhibitor-1 (PAI-1) prothrombin time, and activated partial thromboplastin time were determined using standard methods. We measured flow cytometrically, the platelet activation marker P-selectin on nonstimulated, ADP- and TRAP-6-stimulated platelets. Angiographic data were assessed using the Bollinger score. RESULTS: Plasma levels of the procoagulant proteins fibrinogen (grade I: 3.7/grade II: 3.9/grade m: 4.0 g/l) and vWF (158/156/178%) increased and of antithrombin III (109/103/102%) and the PAI-1/tPA ratio (5.2/5.0/4.1) decreased with progressive disease. Highest platelet activation levels were observed in the CLI grade II subgroup. A significant correlation of disease severity was seen with the ankle-brachial pressure index (p=0.006; r=0.39) and with the Bollinger score (p=0.002; r=-0.41). CONCLUSIONS: Progressive peripheral obstructive arterial disease was associated with platelet hyper-reactivity, haemostatic dysbalance of pro- and anticoagulant proteins, and a counterregulatory increase of fibrinolytic activity. Therapeutic concepts should include these pathogenetic mechanisms.