title: Aortic Valve Function Under Support of a Left Ventricular Assist Device: Continuous vs. Dynamic Speed Support.
abstract: Continuous flow left ventricular devices (CF-LVADs) support the failing heart at a constant speed and alters the loads on the aortic valve. This may cause insufficiency in the aortic valve under long-term CF-LVAD support. The aim of this study is to assess the aortic valve function under varying speed CF-LVAD support. A Medtronic freestyle valve and a Micromed DeBakey CF-LVAD were tested in a mock circulatory system. First, the CF-LVAD was operated at constant speeds between 7500 and 11,500 rpm with 1000 rpm intervals. The mean pump outputs obtained from these tests were applied in varying speed CF-LVAD support mode using a reference model for the pump flow. The peak of the instantaneous pump flow was applied at peak systole and mid-diastole, respectively. Ejection durations and in the aortic valve were the longest when the peak pump flow was applied at mid-diastole among the CF-LVAD operating modes. Furthermore, mean aortic valve area over a cardiac cycle was highest when the peak pump flow was applied at mid-diastole. The results show that changing phase of the reference flow rate signal may reduce the effects of the CF-LVADs on altered aortic valve closing behavior, without compromising the overall pump support level.
authors.affiliation: Department of Biomedical Engineering, Eindhoven University of Technology, Den Dolech 2, 5612 AZ, Eindhoven, The Netherlands, s.bozkurt@tue.nl.
authors.forename: Selim
authors.initials: S
authors.lastname: Bozkurt
authors.forename: Frans N
authors.initials: FN
authors.lastname: van de Vosse
authors.forename: Marcel C M
authors.initials: MC
authors.lastname: Rutten
mesh_terms: D000818:Animals; D001021:Aortic Valve / Q000503:physiopathology*; D006353:Heart-Assist Devices; D006439:Hemodynamics; D006801:Humans; D008955:Models, Cardiovascular