Influence of Inflammation and Pump Dynamic on Cerebral Microembolization in Patients with Continuous-Flow DeBakey LVAD

Abstract

Microembolic signals (MES) have shown to be associated with increased risk of ischemic stroke in patients with pulsatile left ventricular assist devices (LVADs) in contrast to continuous-flow DeBakey LVAD. The pathogenesis of microembolization in LVAD-patients is still not known. We investigated whether systemic markers of inflammation or pump dynamic correlate with cerebral microembolization in nine patients with DeBakey LVAD. We performed transcranial Doppler (TCD) for MES-detection and evaluated parameters of inflammation (i.e. Leukocytes, CRP, Fibrinogen) and pump dynamic (i.e. power, speed, flow). During a mean LVAD duration of 203.7 +/- 179 days, thromboembolic events occurred in five patients with an incidence of 0.38% (approximately 0.38 events/100 LVAD-days). We performed 290 TCD monitorings with a MES mean count of 50.4 +/- 346 signals/hour (0-5042) and prevalence of 42.8%. There was no association between individual microembolic activity and the markers of inflammation or pump dynamic. In patients with DeBakey LVAD, a high load of clinically silent cerebral microemboli can be detected. However, there is no correlation between markers of inflammation or pump dynamic and the individual amount of microembolization. We hypothesize that a gaseous nature of the majority of detected microemboli in the DeBakey LVAD may be the underlying reason for this discrepancy.

Mechanical Circulatory Device Thrombosis: A New Paradigm Linking Hypercoagulation and Hypofibrinolysis

“…14,17,22,39 Thus, if sufficient thrombin generation is present, patients with VADs and hyperfibrinogenemia are at increased risk of forming faster growing, stronger clots that dissolve more slowly than clots formed with normal concentrations of fibrinogen present. 40,41 Further, despite aspirin therapy, patients with VADs may have platelets that are responsive and/or have spontaneous membrane expression of glycoprotein IIb/IIIa and P-selectin, with up to 3-fold normal concentrations of von Willebrand factor present.…”

“…2,7 Conversely, nonpulsatile VADs (e.g., Heartmate II, Thoratec Corporation; DeBakey VAD, MicroMed Cardiovascular, Inc., Houston TX; VentrAssist, Ventracor Limited, Chatswood, Australia) have an improved mechanical durability but are associated with thromboembolic complications and routinely require anticoagulation. 9,[12][13][14]27,28 Thus, significant improvements in the quality and duration of life have been enjoyed by patients with heart failure implanted with VADs compared with similar patients with medical therapy alone, 2,8 significant VAD-associated morbidities still linger.…”

“…In particular, thrombosis/thromboembolism, mechanical failure and infection continue to persist as major sources of morbidity and mortality. [1][2][3][4][5][6][7][8][9][10][11][12][13][14]17,21,22 Despite reduced thrombotic complications 22 with pulsatile VADs (e.g., Heartmate XVE, Thoratec Corporation, Pleasanton CA,) significant mechanical failure over time is observed. 2,7 Conversely, nonpulsatile VADs (e.g., Heartmate II, Thoratec Corporation; DeBakey VAD, MicroMed Cardiovascular, Inc., Houston TX; VentrAssist, Ventracor Limited, Chatswood, Australia) have an improved mechanical durability but are associated with thromboembolic complications and routinely require anticoagulation.…”

Left Ventricular Assist Devices: Engineering Design Considerations

“…Still, the incidence of such events is relatively high accounting for about 19% of patients and a mortality rate of 65% (Davies et al, 2008, Russo et al, 2009, Thoennissen et al, 2006, and Schmid et al, 1998. It may be hypothesized that cerebral thrombo-embolism may be reduced by adjusting the placement and angle of incidence of the LVAD outflow cannula as well as by the implantation of an aortic-toinnominate artery bypass or an aortic-to-left-carotid artery bypass.…”

Occurrence and Clinical Impact of Microembolic Signals During or After Cardiosurgical Procedures

“…[32][33][34][35][36][37][38][39][40] A higher amount of MESs corresponds to thromboembolic events in patients with the Novacor N100 LVAD, 32,34,37 but not in patients with a DeBakey device. 38,40 Patients with the Novacor N100 device and antithrombotic therapy in addition to anticoagulation (eg, antiplatelet agents) had significantly fewer MESs and thromboembolic events. 37 Again, this phenomenon could not be demonstrated in patients with a DeBakey device.…”