Key result
Higher beat rates and shorter diastolic times in the 50cc Penn State VAD increased inflow jet penetration and wall washing, but also increased flow separation near the minor orifice of the aortic valve.
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In a 50cc LVAD model, off-design conditions like higher heart rates improve wall washing but increase flow separation near the aortic valve, highlighting areas for geometric optimization to reduce thrombosis risk.
Particle image velocimetry is used to study the flow field associated with off-design conditions of the 50cc Penn State Ventricular Assist Device. Phase average data, for 300 consecutive beats, was acquired for 60, 75, and 90 beats per minute (bpm) at 35/65 systolic duration and at 75 bpm for 50/50 systolic duration. Diastolic flow is dominated by the inflow jet and shows more penetration and better wall washing at higher beat rates and shorter diastolic time. A flow separation near the minor orifice of the aortic valve, however, is larger under these conditions. Turbulent energy, which peaks during diastole, is found to be strongest at the edges of the jet and near the valves and scales well with the maximum inlet jet velocity. A region of potential separation on the right lateral wall is identified and will be relieved by geometric modifications of the evolving design.
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Oley et al. (2005) studied Ventricular Assist Device (VAD) flow dynamics. Off-design beat rates and systolic durations vs. Normal operating conditions (75 bpm, 35% systolic duration) was evaluated on Flow field characteristics (velocity, separation, turbulence). Higher beat rates and shorter diastolic times in the 50cc Penn State VAD increased inflow jet penetration and wall washing, but also increased flow separation near the minor orifice of the aortic valve.
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