Flow Pulsatility and Outcomes in Continuous-Flow Ventricular Assist Devices

Abstract

Purpose Flow pulsatility, or the fluctuation between low and high flows seen in native circulation, is an important factor in maintenance of normal endothelial and vascular biology. Conversely, the loss of flow pulsatility seen in continuous flow ventricular assist devices (VAD) has been implicated in the development of gastrointestinal (GI) angiodysplasia. We seek to better understand the impact of flow pulsatility on clinical outcomes. Methods We conducted a single-center retrospective cohort study examining hemodynamic and outcomes in HeartWare (HVAD)-supported patients from 2014-2020. Logfile data was interrogated for current, voltage, and pump flow. Flow pulsatility indices (PI) were derived using Granegger's validated pump flow estimation formula (Granegger M, et al. Artificial Organs. 2012). A proprietary algorithm was applied to standardize values between different generations of pump controllers. Results We calculated PI values for 90 patients, 16% of whom were female. Patients who experienced pump thrombosis had significantly higher PI compared to those who did not (1.37 vs. 0.98, p=0.033). Additionally, there were numerically fewer intracerebral hemorrhage (ICH) events in patients with low PI (tertile 1.1) (0 versus 5 and 3 respectively, p=0.052). Other complications including GI or other major bleeding, ischemic stroke, renal dysfunction, and driveline or other major infections did not differ between tertiles. Conclusion Patients with high PI experienced a higher rate of pump thrombosis compared to those with lower PI. This may be due to increased residence time of blood within the pump causing blood stasis and thrombus formation. Larger cohort studies are needed to corroborate these observations and identify other predictors of these important complications of VAD therapy.