Implantable devices in direct contact with flowing blood are currently being used to treat many medical conditions; however, thromboembolism, blood damage and the attendant risk for ischemic stroke remains a major impediment. Specifically, vascular access methods, performed by the insertion of cannulae into vessels, may give rise to non-physiological pressure variations and shear stresses. To date, the hydrodynamic behavior of cannulae has been evaluated by comparing their pressure loss-flow rate relationships, as obtained from in vitro experiments. Numerical studies have evaluated cannulae as rigid wall vessels with steady flow conditions [1]. Various catheter tip styles have been compared [2], and the fluid dynamics of arterial cannulae inserted in the aortic arch have been investigated [3]. Evaluation of shear stresses within a flexible wall cannula under pulsatile blood flow conditions is discussed herein. We anticipate that considerations for pulsating blood flow and flexible device walls will indicate that anticoagulation requirements can be minimized and device related complications can be decreased, thus increasing patient survival rates.

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