Well-Flushed Hydrodynamic Bearing for Miniature Blood Pumps

Ventricular assist devicesVAD sclearly have a role in cardiac medicinehow to precisely define that role is still subject to research and debateconsidering the possibilities of destination therapybridge to transplantbridge to recoverybridge to definitive therapy and possibly other variants one might specifyCertain VAD features are emerging as requiredadequate output to truly make a difference to the patientrealizing that an unloaded ventricle will frequently show significant restoration of functionreliability through the period of usehowever long that might turn out in reality to be after support is institutedease of useminimal morbidities associated with usesuch as those resulting from major surgical invasionbleedingor thrombosisandhigh costs resulting from hardware complexity or demanding post operative careLarge devices can result in extensive tissue organ displacement and large pocketsfurther weakening already very ill patientsproviding locations for bacterial and fungal colonizationand result in extensive adhesions impeding later surgeriesHigh shear stresses can shorten red cell life and disturb both platelet and leukocyte functionThrombosis on the foreign surfaces of the pump can form and later embolizeand or systemic coagulation pathologies occurAggressive pump anticoagulation protocols limit a clinician s ability to respond to other patient issuesPerfusion SolutionsIncPSIhas a new bearing technology which promises to address these issuesSmall hydrodynamic bearings are located before and after the rotorin the main flow streamThe unload side of the bearing is open to the blood flowMagnetic radial loading ensures proper rotor positioningUnlike similarly sized pivot supportsthese bearings are not only continuously washed by blood flow but also have the surfaces separated by a hydrodynamically generatedwear free fluid filmComplexity and costs are much lower than new generations of magnetic bearing pumpsThe PSI hydraulic design approach has demonstrated low bench hemolysis and baseline free hemoglobin inday lamb implantsThe PSI design configuration is readily adaptable to many surgical approachesour initial packaging of the core hardware is directed to suit an intrathoracic implant via port surgery for medium term to permanent supportPhase I will use bench tests to demonstrate hydraulic performancelow hemolysisacceptable surface temperatures and initial freedom from axial or radial wearDuring phase IIadditional pump prototypes will be built and used forandday in vivo studieswhile the Phase I pumps continue on long term endurance testingPhase II will also explore anti coagulation free pump surfaces Heart disease is a major source of mortalityloss of quality of lifeand high medical costs for treatmentBlood pumps have shown a potential to not only save livesbut to rehabilitate patients to a much higher level of functionHoweverpresent technology still has a significant number of limitations which cause death and disability and high hospitalization costs as a result of the pump implantthe proposed project addresses some of these limitations by minimizing device sizetissue displacementand hardware complexity