简介：CoronaryArteryBypassGraft(CABG)isanimportantsurgicaltreatmentforcriticallystenosedarteries.UnfortunatelyrestenosisalwaysoccursafterCABGsurgery,whichbringaboutsurgeryfailure,lntimalthickeningintheCABGdistalanastomosishasbeenimplicatedasthemajorcauseofrestenosisandlong-termgraftfailure.Thenonuniformhemodynamicsincludingdisturbedflows,recirculationzones,oscillatingwallshearstress,andlongparticleresidencetimewerethoughttobethepossibleetiologies.NumericalsimulationwasprovedtobeofgreathelpandguidancemeaningforthebiofluidmechanicsresearchandtheCABGsurgicalplan.ThepresentstudywasbasedonthehypothesisthatthegeometryconfigurationofCABGcouldgreatlyinfluencethehemodynamicsinthevicinityofanastomosis.Thehemodynamicfeaturesoftwogeometrymodelsofend-to-sideCABGwerestudiedandcompared.OnesimulatedaconventionalCABGwith1-waybypassgraft,andtheothersimulatedamodifiedCABGwithsymmetric2-waybypassgraft.Thenumericalinvestigationsofhemodynamicsinthesetwomodelswithfullystenosedcoronaryarterieswereaccomplishedusingfiniteelementmethod.Thetemporalandspatialdistributionsofhemodynamicswereanalyzedandcompared.Resultsshowedthatthepresenceofsymmetric2-waybypassgraftwasofreasonableandfavorablehemodynamicsthan1-waybypassgraft.ThemodifiedCABGmodelcreatedamorehemodynamicallyefficientstreamlinedenvironmentwithhighermeanandmaximumaxialvelocitiesandlowerradialvelocitiesthantheconventional1-waymodel.Meanwhile,thesymmetric2-waybypassgraftwasfeaturedwithlowpressurenearthewall,highanduniformWSSinthehostartery.Allofthesewerefavorableforinhibitingthedevelopmentofintimalthickening,restenosis,andultimatefailureoftheCABG,anditcouldconsiderablyimprovetheflowconditionsanddecreasetheprobabilityofintimalhyperplasiaandrestenosisofCABG.

简介：Sinceitsintroductionin1967,intra-aorticballoonpumping(IABP)hasbecomethemainstayinthemanagementofacuteleftventriculardysfunctioninthecriticalcaresetting.Typically,presentIABPsystemsareunabletoprovideconsistent,effectivecar-diacassistanceinthepresenceofarrhythmiasorrapidlychangingheartrates.Anew-generation,closedloop,fullyautomaticintra-aorticballoonpump(CL-IABP)