Computational fluid dynamics analysis of surgical adjustment of left ventricular assist device implantation to minimise stroke risk

Abstract

The adjustment of the location of the anastomosis of the LVAD outflow cannula as well as its angle of incidence plays a significant role in the level of thromboembolisms. By proper adjustment in this CFD study of a synthetic model of an aortic arch bed, we found that nearly a 50% reduction in cerebral embolism could be achieved for a configuration consisting of a shallow angle of implantation over a baseline normal incidence of the LVAD cannula. Within the limitations of our model, we have established that the LVAD implantation geometry is an important factor and should be taken into consideration when implanting an LVAD. It is possible that other parameters such as distance of the LVAD outflow cannula to the root of the IA could affect the thrombi embolisation probabilities. However, the results of this study suggest that the risk of stroke may be significantly reduced by as much as 50% by tailoring the VAD implantation by a simple surgical manoeuvre. The results of this line of research may ultimately lead to techniques that can be used to estimate the optimal LVAD configuration in a patient-specific manner by pre-operative imaging.

Aortic Outflow Cannula Tip Design and Orientation Impacts Cerebral Perfusion During Pediatric Cardiopulmonary Bypass Procedures

“…The aortic cannula must ideally be placed high up in the ascending aorta 10 but improper technique can occasionally result in profuse bleeding as a result of improper cannula placement. To date, CPB has been studied in regard to clinical stroke-risk, 2 but there have been few reported studies of the detailed fluid dynamics associated with aortic cannulation, 15,16,31,40 all underscoring the association of biomechanical risks with aortic cannulation. Despite advances in surgical techniques leading to decreased mortality after repair of complex congenital cardiac conditions, neurologic morbility is still significant.…”

Lagrangian Postprocessing of Computational Hemodynamics

“…(6), or similar dynamical model. This may be relevant in modeling of embolic particles, which has previously been performed to model thromboemboli [107, 28]. The Stokes number (characteristic time of a particle to characteristic time of the flow) of cellular elements is typically < 0.001 in larger arteries and hence cells can be treated as material points.…”

Physiological Impact of Continuous Flow on End-Organ Function: Clinical Implications in the Current Era of Left Ventricular Assist Devices

“…Interruption of anticoagulant and antiplatelet medications were responsible for a 47% occurrence of ischemic stroke in the cohort that had a hemorrhagic stroke, 30 but such interruption was not a contributor for primary ischemic stroke in multivariate analysis. Other possible contributing factors for stroke in CF-LVAD include anatomical factors of outflow graft orientation 31 and stasis in the carotid bulb due to increased laminar flow. 32 Infection leading to bacteremia and septic emboli are added mechanisms specific to VAD patients due to their high prevalence of chronic infections.…”