Platelet activation and aggregation profile in prolonged external ventricular support.
BACKGROUND
Platelet function plays a major role in the understanding of thromboembolic events in prolonged mechanical support. We studied the platelet activation, platelet aggregation profile, and efficacy of aspirin in patients in whom an external ventricular assist device had been implanted.


METHODS
Fifteen patients were studied prospectively up to 6 weeks after implantation of the same type of ventricular assist device. Platelet function was studied weekly before daily aspirin administration. Aspirin efficacy was tested ex vivo by measuring platelet aggregation triggered by arachidonic acid. Flow cytometry was used to quantify the spontaneous and induced (adenosine diphosphate stimulation) expression of glycoproteins alphaIIbbeta3, Ibalpha, and CD62P on platelet membranes. The plasma levels of von Willebrand factor (von Willebrand factor activity and von Willebrand factor antigen) and fibrinogen were also determined.


RESULTS
Six of the 15 patients (26%) maintained an arachidonic acid-induced platelet aggregation despite daily aspirin treatment (250 mg). CD62P values remained increased during a 5-week postoperative period. Spontaneous levels of glycoproteins alphaIIbbeta3 and Ibalpha on platelet membranes remained within a normal range with a preserved reactivity. The plasma levels of fibrinogen and von Willebrand factor remained increased during the entire study period.


CONCLUSIONS
In patients with an implanted external ventricular assist device, the platelet activation profile displays a persistent activation with a preserved reactivity associated with a persistent high inflammatory state and endothelial activation.
Service de Chirurgie Cardiaque, Hôpital Henri Mondor, Créteil, France. remihouel@hotmail.com
Rémi
R
Houël
Elisabeth
E
Mazoyer
Bernadette
B
Boval
Mathias
M
Kirsch
Emmanuelle
E
Vermès
Ludovic
L
Drouet
Daniel Y
DY
Loisance
D000293:Adolescent; D001241:Aspirin / Q000627:therapeutic use*; D005260:Female; D006353:Heart-Assist Devices; D006801:Humans; D008297:Male; D008875:Middle Aged; D015539:Platelet Activation / Q000187:drug effects*; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000627:therapeutic use*; D011446:Prospective Studies; D013997:Time Factors
D010975:Platelet Aggregation Inhibitors; D001241:Aspirin