Mathematical Modeling of Patient Specific Ventricular Assist Device Implantation to Reduce Particulate Embolization Rate to Cerebral Vessels

Abstract

Stroke is the most devastating complication after ventricular assist device (VAD) implantation, with an incidence of 14%–47% despite improvements in device design and anticoagulation. This complication continues to limit the widespread implementation of VAD therapy. Patientspecific computational fluid dynamics (CFD) analysis may elucidate ways to reduce this risk. A patientspecific threedimensional model of the aortic arch was generated from computed tomography. A 12 mm VAD outflowgraft (VADOG) “anastomosedâ€‌ to the aorta was rendered. CFD was applied to study blood flow patterns. Particle tracks, originating from the VAD, were computed with a Lagrangian phase model and percentage of particles entering the cerebral vessels was calculated. Twelve implantation configurations of the VADOG and three particle sizes (2, 4, and 5 mm) were considered. Percentage of particles entering the cerebral vessels ranged from 6% for the descending aorta VADOG anastomosis, to 14% for the ascending aorta at 90 deg VADOG anastomosis. Values were significantly different among all configurations (X2 = 3925, p < 0.0001). Shallower and more cephalad anastomoses prevented formation of zones of recirculation in the ascending aorta. In this computational model and within the range of anatomic parameters considered, the percentage of particles entering the cerebral vessels from a VADOG is reduced by nearly 60% by optimizing outflowgraft configuration. Ascending aorta recirculation zones, which may be thrombogenic, can also be eliminated. CFD methods coupled with patientspecific anatomy may aid in identifying the optimal location and angle for VADOG anastomosis to minimize stroke risk.