Physiological vortices in the sinuses of Valsalva: An in vitro approach for bio-prosthetic valves

Purpose: The physiological flow dynamicswithintheValsalvasinuses,intermsofglobalandlocal parameters,arestillnotfullyunderstood.Thisstudyattemptstoidentifythephysiologicalconditionsas closely aspossible,andtogiveanexplanationofthedifferentandsometimecontradictoryresultsin literature. Methods: An in vitro approach wasimplementedfortestingporcinebio-prostheticvalvesoperating within differentaorticrootconfigurations. Alltestswereperformedonapulseduplicator,underphy- siological pressureand flow conditions.The fluid dynamicsestablishedinthevariouscaseswereana- lysedbymeansof2DParticleImageVelocimetry,andrelatedwiththeachievedhydrodynamicperfor- mance. Results: Each configuration isassociatedwithsubstantiallydifferent flowdynamics,whichsignificantly affects thevalveperformance.Theconfiguration mostcloselyreplicatinghealthynativeanatomywas characterisedbythebesthemodynamicperformance,andanymismatchinsizeandpositionbetween the valveandtherootproducedsubstantialmodification ofthe fluid dynamicsdownstreamofthevalve, hindering thehydrodynamicperformanceofthesystem.Theworstconditionswereobservedfora configuration characterisedbythetotalabsenceoftheValsalvasinuses. Conclusion: This studyprovidesanexplanationforthedifferentvorticalstructuresdescribedinthelit- eraturedownstreamofbioprostheticvalves,enlighteningtheexperimentalcomplicationsinvalve testing. Mostimportantly,theresultsclearlyidentifythe fluid mechanismspromotedbytheValsalva sinuses toenhancetheejectionandclosingphases,andthisstudyexposestheimportanceofanoptimal integrationofthevalveandroot,tooperateasasinglesystem.