Treatment of end-stage heart failure includes cardiac transplantation or ventricular assist device (VAD) therapy. Although increasingly prevalent, current VAD therapy has inherent complications, including thrombosis. Studies have demonstrated that VAD implantation alters intracardiac blood flow, creating areas of stagnation that predispose to thrombus formation. Two potential surgical configurations exist for VAD implantation: through the apical or diaphragmatic surfaces of the heart. We hypothesized that diaphragmatic implantation causes more stagnation than apical implantation. We also hypothesized that intermittent aortic valve (AV) opening reduces stagnation of blood inside the left ventricle (LV) when compared with a closed AV. To test these hypotheses, a human LV geometry was recreated in silico and a VAD inflow cannula was virtually implanted in each configuration. A computational indicator-dilution study was conducted where “virtually dyed blood” was washed out of the LV by injecting blood with no dye. Simulations demonstrated a substantial reduction in stagnation with intermittent AV opening. In addition, virtual dye was cleared slightly faster in the apical configuration. Simulations from our study demonstrate the clinical importance of VAD management to allow intermittent opening of the AV to prevent subvalvular stagnation, and also suggests that apical configuration might be more hemodynamically favorable.
From the *Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, Wisconsin; †Department of Medicine, University of Minnesota, Minneapolis, Minnesota; ‡Department of Mechanical Engineering, University of Washington, Seattle, Washington; §Department of Medicine, Division of Cardiology, University of Washington, Seattle, Washington; ¶Department of Surgery, Division of Cardiothoracic Surgery, University of Washington, Seattle, Washington; and ‖Department of Otolaryngology, Medical College of Wisconsin, Milwaukee, Wisconsin.
Submitted for consideration July 2016; accepted for publication in revised form November 2016.
Disclosure: N.A.M. has a consulting relationship with St. Jude and HeartWare and is an investigator for St. Jude, HeartWare, and SynCardia. C.M. has consulting relationships with St. Jude, Abiomed, and HeartWare and is an investigator for St. Jude, HeartWare, and SynCardia. J.A.B. has consulting relationships with St. Jude, Abiomed, and HeartWare.
This project was supported in part by the National Center for Advancing Translational Sciences, National Institutes of Health, through Grant Numbers 8KL2TR000056 and UL1TR001436. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIH.
Correspondence: Guilherme J. M. Garcia, Department of Biomedical Engineering, Medical College of Wisconsin, 8701 Watertown, Plank Road, Milwaukee, WI 53226. Email: firstname.lastname@example.org.