Left Ventricular Assist Devices: Impact of Flow Ratios on the Localisation of Cardiovascular Diseases Using Computational Fluid Dynamics

The use of Left Ventricular Assistive Devices (LVADs) is increasing for people with heart failure. The present computational fluid dynamics study provides insight into the significance of the flow ratio between the cannula and the aortic root on the prediction of lesion localisation in a typical LVAD configuration, which in turn affects the design and manufacture of these devices. Three cases were studied with varying percentages of flow through the two inlets; the cannula inlet was assumed steady-state, whilst the aortic root inlet had a scaled pulsatile profile, representative of the extent of heart failure. Results suggest that as the flow exiting the heart decreases in velocity, if not orientated properly, the jet exiting the cannula graft can ‘obstruct’ flow to the innominate, common carotid and left subclavian arteries. Therefore, patients with less severe heart failure will generally experience relatively good perfusion of these arteries. However, for the more severe cases of heart failure, the orientation of the cannula graft should be such that adequate perfusion to the aforementioned arteries is maintained.