Hemorrhage and thrombosis with different LVAD technologies: a matter of flow?

Background: Much of the morbidity and mortality associated with ventricular assist devices (VADs) is due to haemorrhagic and thrombotic complications. To manage antithrombotic therapy, interactions between the patient and pump should be better understood.
Methods: We have compared the Jarvik 2000, an axial flow left ventricular assist device (LVAD), with the HeartWare ventricular assist device (HVAD) centrifugal pump, regarding conventional laboratory findings, thromboelastometric and aggregometric tests.
Results: Patients with the Jarvik 2000 experienced a significant reduction in platelet count following implantation, a phenomenon not seen with the HeartWare model. Conversely, we observed that levels of platelet activation, as assessed by a platelet function analyzer, and activation of the coagulation system, as assessed by thromboelastometry, were significantly greater in the HeartWare group.
Conclusions: It seems that axial flow pumps, being more destructive on blood cells, tend to reduce platelet numbers. On the other hand, centrifugal flow is associated with a hypercoagulable state, possibly resulting from the activation of the coagulation system in the absence of platelet destruction.