title: Platelet aggregability in patients with a VVI pacemaker.
abstract: Several studies have suggested an increased incidence of thromboembolic events in patients with VVI pacemaker (VVI patients); furthermore, other authors have demonstrated that a treatment with anticoagulants or antiplatelet drugs may be effective in reducing thromboembolic events, thus suggesting an increased formation of platelet thrombi in these patients. In this respect, platelet aggregability was investigated in ten VVI patients and ten age- and sex-matched subjects. beta-thromboglobulin (beta-Tg) and platelet factor 4 (PF4) plasma levels were determined as well as platelet aggregation induced by ADP, collagen, epinephrine, and arachidonic acid. Plasma beta-Tg levels were increased in the patient group (86 +/- 24 vs 24 +/- 13 ng/mL; P < 0.001) in presence of normal PF4 values (14 +/- 11 vs 13 +/- 6 ng/mL; NS). Aggregation curves showed abnormal values of maximal amplitude, slope, and lag time. In particular, maximal amplitude was significantly higher in VVI patients as compared with controls (ADP P < 0.01, collagen P < 0.001, adrenaline P < 0.01, arachidonic acid P < 0.05). These findings strongly suggest an increase of platelet activity in VVI patients.
authors.affiliation: Department of Internal Medicine, 2nd Medical School, Federico II University, Naples, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Fazio
authors.forename: A
authors.initials: A
authors.lastname: Cittadini
authors.forename: D
authors.initials: D
authors.lastname: Sabatini
authors.forename: M
authors.initials: M
authors.lastname: Santomauro
authors.forename: M
authors.initials: M
authors.lastname: Cocozza
authors.forename: U
authors.initials: U
authors.lastname: Oliviero
authors.forename: M
authors.initials: M
authors.lastname: Chiariello
authors.forename: L
authors.initials: L
authors.lastname: Sacca
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000368:Aged; D016718:Arachidonic Acid / Q000494:pharmacology; D003094:Collagen / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology; D005260:Female; D006801:Humans; D008297:Male; D010138:Pacemaker, Artificial; D010974:Platelet Aggregation / Q000187:drug effects; D010978:Platelet Factor 4 / Q000032:analysis; D001620:beta-Thromboglobulin / Q000032:analysis
chemical_list: D001620:beta-Thromboglobulin; D016718:Arachidonic Acid; D010978:Platelet Factor 4; D000244:Adenosine Diphosphate; D003094:Collagen; D004837:Epinephrine