IMPROVED FLOW STRAIGHTENERS REDUCE THROMBUS IN THE NASA DEBAKEY AXIAL-FLOW VENTRICULAR ASSIST DEVICE/

A small axial flow ventricular assist device (VAD) measuring 3 inches long and 1 inch in diameter is in development. The pump consists of a spinning inducer/impeller, a flow straightener (FLS), and a diffuser e nclosed in a cylindrical flow tube. The impeller has rod-shaped perman ent magnets embedded within its 6 blades and is activated magnetically by the motor stator which is positioned outside the flow tube. At the completion of a previous study, the FLS was identified as a thromboge nic area. The aim of the present study was to evaluate the thrombogeni city of redesigned FLSs (swept-back and bulbous types), compared with standard type (STD) FLS. A total of 15 pumps (STD, n = 7; swept-back, n = 4; and bulbous, n = 4) were sequentially implanted into 4 calves p aracorporeally in a short-term ex vivo test. The STD and bulbous FLSs experienced thrombus formation, but the swept-back FLS was thrombus fr ee during a 48 h screening test.